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Altech® Introduces Industry ‘First’ UL 489 Ground Fault Equipment Protector Augmenting Complete Lineup to Help Prevent Costly Production Shutdowns


A complete line of UL Ground Fault Equipment Protection (GFEP) devices from Altech Corp.® – including an industry “first” – introduce ideal solutions to help prevent costly production shutdowns due to AC and DC pulsating ground faults, as well as overloads and (with some models) short circuits.  The technology lineup – unmatched in the industry – offers three highly engineered series of devices delivering multiple capabilities and promoting reliable protection and operation of equipment wherever and whenever ground faults may occur.  In all three series, ground fault sensitivity levels range from 10 mA – 500 mA.

The UL 489 Branch Circuit Breaker with Ground Fault Relay (GFL Series) represents an industry “first” by combining a Ground Fault Equipment Protector with a UL 489 Branch Circuit Protector, which eliminates a need for upstream circuit protection.  This device is available in 1 pole+N, 2 pole, and 2 pole+N configurations at 120/240V AC and 240V AC.  Rated current is 5A-40A and rated Short Circuit Interrupt Capacity is 10kA.  Three trip curves (B, C, and D) can be specified.

The UL 1053 Ground Fault Sensing and Relaying device (GF Series) provides residual current protection for circuits with loads up to 63A.  This model is designed with 2 and 4 poles at 277V AC and 480Y/277V AC, rated current of 25A, 40A, and 63A, and rated Short Circuit Withstand Capacity of 10kA.  This device represents an ideal retrofit GFEP where standard overload and short circuit protection is already being provided (or will be provided) by other means.

The UL 1077 Ground Fault Relay with Overload Protection (GFR Series) serves as a combined Equipment Ground Fault Relay and Supplementary Protector (RCBO).  The device can be supplied with 2 and 4 poles at 277V AC and 480Y/277V AC and with a rated current of 5A-40A.  Rated Short Circuit Withstand Capacity is 10kA and three trip curves (B, C, and D) are offered.   

These three series are the latest additions to Altech’s UL listed product range dedicated to meet the most demanding conditions and applications across industries.  Altech further provides comprehensive product support and the capability to develop customized solutions to meet particular requirements.

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Ground Fault Current Protection Devices
Prevent Costly Production Shutdowns


Figure.1 Altech’s three new series deliver multiple capabilities.  In all three series, ground fault sensitivity levels range from 10 to 500 mA.

An unintentional electric path between a source of current and a grounded surface is referred to as a "ground fault." Ground faults occur when current is leaking somewhere. It is frequently the result of insulation breakdown or loss when age or other environmental factors degrade the conductor insulation, causing an inadvertent contact between a live conductor and ground. Most short circuits initially manifest as ground faults; if undetected, they can cause serious and costly damage to electrical systems and equipment, crippling production and disrupting supply chains.

Ground fault protection of equipment (GFPE) can prevent these faults in automated processes and reduce or eliminate costly plant downtimes. Ground fault protection is essential in commercial, industrial, and institutional facilities such as (but not limited to):

  • Chemical Plants,
  • Refineries,
  • Waste water treatment plants,
  • Semiconductor facilities,
  • Pharmaceutical plants, and
  • Other plants near water (especially salt water).

Ground fault protection of equipment (GFPE) is defined in Article 100 of the National Electrical Code (NEC) as “a system intended to provide protection of equipment from damaging line-to-ground fault currents by operating to cause a disconnecting means to open all ungrounded conductors of the faulted circuit." The focus of the NEC, which is a code developed by the National Fire Protection Association (NFPA), is primarily fire prevention. Circuit protection is required to prevent fires from occurring due to overcurrent faults or short-circuits.
GFPE devices work by quickly and automatically disconnecting a circuit when it detects that the electric current is not balanced between the energized (line) conductor(s) and the return (neutral) conductor. Apart from saving production equipment from unnecessary downtime (and potential injury to personnel) these devices also can help with:

  • Motor winding failure detection,
  • “Surveillance” on wire insulation, and
  • Detecting potential short circuits before they occur.

Altech offers a wide variety of solutions to help prevent production shutdowns due to AC and DC pulsating ground faults, as well as overloads and short circuits. This article will look at its newest technology lineup — including an industry “first” — consisting of three series of devices; in all three series, ground fault sensitivity levels range from 10 mA – 500 mA.

Three New Series

Altech’s GFL series is the industry’s first combination of a UL 489 Branch Circuit Protector with a Ground Fault Equipment Protector. By way of review, a branch circuit is the wiring portion of a system extending beyond the final overcurrent device protecting the circuit. A Ground Fault Equipment Protector which is intended to protect equipment from damage should not be confused with five mA ground fault circuit interrupters (GFCIs), which provide personnel protection from electrical shock.

GLF series devices are designed to provide protection against short circuits, overloads, AC ground faults (residual current faults), and pulsating DC ground faults. Eliminating the need for upstream circuit protection, GFL devices are available in one pole+N, two pole, and two pole+N switching — live and neutral disconnect — at 120/240 V AC and 240 V AC.

The number of poles represents the number of conductors that are interrupted when a fault condition occurs. A single-pole device interrupts only the energized conductor, while a double-pole device interrupts both the energized and return conductors.The +N terms signify that the return, or neutral conductor is an isolating pole only. 

Ground fault sensitivity levels for the GLF series range from 10 mA–500 mA.  Rated current is 5 A–40 A and rated Short Circuit Interrupt Capacity is 10 kA.

UL 489, “Standard for Molded-Case Circuit Breakers and Circuit Breaker Enclosures,” published by Underwriters Laboratories, Inc. spells out requirements for overcurrent protection devices in a branch circuit. For approval, UL 489 requires the device pass a series of calibration, overload, endurance, and short-circuit tests. Minimum short-circuit tests are performed at 5000 A. Overload tests are performed at six times the current rating of the device, or 150 A minimum. Devices rated up to 600 V and 6,000 A are covered in this standard.  The device must survive short-circuit testing and continue to provide future overload protection.



Figure 2. GFL series RCBO overload (top) and ground fault (bottom) trip curves.

Circuit breaker operating characteristics are graphically presented on time/current characteristic curves, commonly called trip curves, that plot tripping time versus current level. The curve (Fig. 2 top) shows the amount of time required for a circuit breaker to trip at a given overcurrent level. For GLF devices, for instance, three overload trip curves (B, C, and D) can be specified. The Type B characteristic is designed for European residential circuit protection. This characteristic can also be used for protection of computers and electronic equipment. The Type C characteristic is for general device protection in control circuits, and the Type D characteristic is designed for high inrush loads. These curves are developed using predefined specifications such as operation at an ambient temperature of 40° C. For different ambient temperatures, the current values of the tripping operation can change by approximately 5%
per 10° K temperature difference.

The Ground fault Characteristic Curve for the GFL series is shown in Fig. 2 (bottom). The ground fault function consists of a pickup and delay setting. The pickup portion determines at what point the circuit breaker will begin detecting a ground fault. The delay adjustment determines how long the circuit breaker will delay tripping after a ground fault has been detected.

UL standard 1077 covers supplementary protectors used in equipment. A supplemental protector is defined as an overcurrent device for protection of the end circuit; it may be added to a circuit to provide an extra level of protection for a specific component. These devices require the use of an upstream protective device so, generally, these protectors have lower short-circuit protection, as it's assumed that there's branch circuit protection upstream. Where UL 489 devices are tasked with conductor protection, protection of the load is the primary purpose of selecting a UL 1077 device.

When your application requires supplemental protection for control circuits and on the load side of branch circuit protectors, Altech’s UL1077 solution is the GFR series. GFR devices can be supplied with two and four poles at 277 V AC and 480 Y/277 V AC and with a rated current of 5 A–40 A.  Rated Short Circuit Withstand Capacity is 10 kA.


Figure.3 Altech’s two pole GFR series combines a Ground Fault Relay and a supplementary protector

The GFR series (Fig. 3)  is a space-saving design as it serves as a combined equipment Ground Fault Relay and Supplementary Protector (RCBO or residual-current circuit breaker with overcurrent protection). The GFR series features dual pole switching (live and neutral) and is designed to provide protection against overloads and AC ground faults (residual current faults) as well as pulsating DC ground faults. A ground fault relay detects all phase-to-ground faults within its defined zone of protection under conditions which produce minimum fault current. Ground fault relays are used to sense low magnitude ground faults. When the ground fault current magnitude and time reach the ground fault relay pick up setting, the control scheme signals the circuit disconnect to open.

Similar to UL 489, UL 1077 supplementary protectors must pass a series of calibration, overload, endurance, and short-circuit tests. A supplementary protector can be overload tested at 1.5 times its rating for general use or six times its rating for motor starting. It may trip at less than 125% of its rating or greater than 135%.  Unlike UL 489, UL1077 devices do not necessarily need to survive the test.

The GF Series of UL 1053 Ground Fault Sensing and relaying devices provides residual current protection for circuits with loads up to 63 A in one to three poles at 480 Y/277 V AC with a 10 kA short circuit withstand rating. Three trip curves (B, C, and D) are offered.  Designed with two and four poles, the series offers rated current of 25 A, 40 A, and 63 A, and is rated a Short Circuit Withstand Capacity of 10 kA. It represents a retrofit GFEP, where standard overload and short circuit protection is already being provided (or will be provided) by other means.

UL1053 requirements cover equipment intended for use in circuits that are solidly grounded. They do not cover ground fault circuit-interrupters, nor equipment intended to be powered from single-phase circuits operating at more than 600 V or three-phase circuits operating at more than 600 V phase-to-phase.

The Altech Advantage

The three series mentioned above are the latest additions to Altech’s UL listed product range. Designed to meet the most demanding conditions, these competitively priced, technically correct circuit protection devices cover most applications where meeting UL and NEC requirements is essential. Altech further provides comprehensive product support and the capability to develop customized solutions to meet particular

Battery Management: Altech’s Versatile Charging Solutions
Murray Slovick

Efficient, rechargeable and economical battery systems are needed in a wide variety of industries. Uses can range from generator sets to transceiver base stations, from onboard chargers for electric vehicles to water pumps. Proper recharging and maintenance of these batteries requires an intelligent charging system that can vary the charging voltage based on the state of charge and use of the battery. And while these battery chargers can differ in terms of design and the battery chemistry they are suited to, with proper selection and use, a battery charger can restore even a flat industrial battery to a fully charged state.

Equipped with Microcontrollers
Altech’s multi-stage battery chargers operate automatically and are well-matched to the most advanced requirements of battery manufacturers. Real-time diagnostics allows for fast recharge and recovery of deeply discharged batteries and enable the user to monitor battery faults, disconnections and charge status. In addition, they will monitor the ambient temperature and adjust charging parameters accordingly.

Altech CBI All-In-One DC-UPS

Figure 1: Charging flow diagram. Source: Altech

Each device is suited for a wide variety of battery types. By means of jumpers, it is possible to set predefined charging curves for open lead-acid, sealed lead-acid, gel, nickel-cadmium (Ni-Cd) and nickel-metal hydride (NiMH) batteries (as an option). It is possible to change or add other charging curves by connecting the device to a portable PC. Similarly, it is possible to carry out functional software updates just using any laptop computer. Doing so allows the system to always be up-to-date with changing requirements.

Altech smart chargers will detect voltage and resistance from the battery prior to charging, and then stop the charging cycle automatically when a rechargeable battery is fully charged. The company’s CB series battery chargers are based on switching technology that allows much higher efficiency (up to 91 percent), as well as smaller and lighter devices than is possible with traditional linear technology battery chargers. What is more, standard safety and protection features ensure safe installation and operation. The bus system included with many of these products satisfies all ModBus 485 protocols and CAN bus J1939 bus protocols for connection to GenSets.

CB Series Battery Chargers: A Closer Look
In its CB series, Altech offers a highly reliable battery management solution operating at single phase, with wide input voltages of 115‑230‑277 V AC and supplying an output of 12 V DC and up to 35 A, 24 V DC and up to 20 A and 48V DC up to 10A.

CB series chargers feature three charging modes (Figure 2): recovery, boost and trickle, each identified by a flashing code on an LED. In recovery mode, the unit can recharge and completely recover severely drained batteries, even when their voltage is close to zero. Recovery mode is indicated by an LED blinking five times per second. Boost is the fastcharge mode. To indicate boost mode, the LED blinks twice per second. The float stage then brings the battery all the way through and maintains a 100 percent state of charge. The current will also decrease to a point where it's considered a trickle (that's where the term "trickle charger" comes from). To indicate float charging mode, the LED blinks once each second. During trickle charge, the quality (resistance) on the battery connection is checked every 20 seconds. When the battery is completely full, the device automatically switches into trickle charging mode.

Altech CBI All-In-One DC-UPS
Figure 2: Graph depicting the three charging modes of a CB series charger. Source: Altech

The CB series features real-time auto-diagnostics for monitoring battery faults and disconnections. A flashing LED sequence code allows users to discriminate among various possible faults. For example:

  • One flash: Reverse polarity, wrong battery voltage.
  • Two flashes: Disconnected battery.
  • Three flashes: Battery element in short circuit.
  • Five flashes: Battery to be replaced (internal impedance is bad or bad battery wire connection).

This high performance battery charger and DC UPS product meet with a wide variety of applications such as machine building, system manufacturing, building automation, ship building, process technology, building safety, oil and gas metering, and equipment safety requirements.

Power Continuity: The CBI All In One Series
Altech’s CBI All In One UPS Power Solutions combine the requirements for several applications in just one device that can be used as a power supply unit, battery charger, battery care module or backup module. The available power is automatically distributed among load and battery; it should be noted that supplying power to the load is always the first priority. Continuous monitoring of battery efficiency reduces battery damage risk and allows safe operation. Like the CB series, CBI devices are suited for a wide variety of battery types: open lead-acid, sealed lead-acid, gel, Ni-Cd and NiMH.

Altech CBI All-In-One DC-UPS
Figure 3: CB charger LED codes. Source: Altech

The available charging options are recovery, boost and trickle charge. Also, as in the CB series, CBI devices provide microprocessor-controlled battery charging. Using algorithms, the battery’s condition will be detected and the appropriate charging mode is chosen.

Load output will not be affected by battery conditions. The DC-UPS ensures continuous power supply to the load even in conditions of completely discharged batteries. Its automatic, multi-stage operation optimizes and adapts to the battery status. The CBI series real-time diagnostics system continuously monitors charging progress and provides a flashing code of the diagnosis.

Altech’s CBI Series product meets the highest standards of quality and ensures high reliability with MTBF values of up to 300,000 hours.

With a variety of battery chargers available on the market, it is important to choose the charger best-suited to your application. Visit the Altech website for more information on high-quality, microcontroller-based battery chargers and DC UPS solutions.

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Foot Switch Selection Guidelines and Selection Options

Why is the correct selection of a foot switch important?
Foot switches are designed to provide the user with comfortable, hands-free activation of one or more processes of a given device—making ergonomics important. Choosing the proper foot switch design will create a positive first impression of the overall device and installation. More importantly, the foot switch must offer attributes that represent the quality and design of the equipment as well as being the main machine/operator interface.

What is the difference between medium and heavy-duty foot switches?
Medium-duty foot switches are intended for lighter manufacturing machines and medical equipment. When mobility is a concern, the plastic fabrication of these switches will reduce weight for easy transport. Options include covers, foldable carrying handles, and metal bases to add stability. Heavy-duty foot switches, designed for rugged applications such as metal and wood working equipment, are typically made of a heavy metal and
often have a hood, both to prevent accidental operation and protect against damage. The hood is usually oversized to allow activation by operators wearing large protective boots. Heavy-duty foot switches are typically used in a fixed position where weight and mobility are not concerns.

What do I have to know about the electrical rating?
As with most dry contact switching devices, the maximum switching power of standard foot switches is rated in voltage and amperage—helpful when selecting the proper cable size as well. Some foot switches also reference horsepower, although it is more accurate to use a Motor Full Load Amperage


Chart to determine the maximum size load a foot switch can control.

What do I have to know about the contacts for the foot switch?
Pedal contacts are configured as normally open (NO) or normally closed (NC), which indicates whether the switch is opened or closed when untouched—and the opposite when the pedal is depressed. Contact configurations may change depending on the switch you’ve ordered or the manufacturer. This table illustrates some typical configurations. Form C contacts are typically “Break Before Make,” meaning the NC contacts
break connection before the NO contacts make connection.

Are there different pedal actions available?
Yes. Pedal action refers to what happens when the pedal is pressed and released. For example, momentary action is when the contacts change states once the pedal is pressed and return to their original state once released. Maintained (or latching) action is when the contacts change state when the pedal is pressed and remain so when released. The pedal must be pressed again to return the contacts to their original state. Twostage action is when a user applies pressure to the pedal and the first set of contacts change state. As the user pushes further (past a pressure point), a second set of contacts change state. When the pedal is released the contacts return to their original state in reverse order.

What is the difference between slow and snap action?
Slow action contacts use a slide system driven directly by the downward force of the pedal mechanism, while snap action contacts have a double spring-loaded slide system that snaps the contacts into place after a trip
point is reached.

What different contact plating materials are common?
Silver-nickel plating is the most common, but gold plating can also be used in low-current (<0.1 Amp) applications. Note that exposure to high voltages can cause gold to “burn off.”

What is mean by the protection rating?
Foot witches are typically classified using the Ingress Protection (IP) system. These ratings define the level of sealing effectiveness of electrical enclosures against intrusion from foreign bodies whether
dust, dirt, or moisture.

What type of cable and/or connector can be used?
Connectors allow the foot switches to be easily installed or replaced, and selection is based on the number on poles, their voltage and amperage, and the installation environment. For cabling, the only selection limitation is the voltage/amperage rating and the diameter of the conductors and cable jacket. A cable with a tough jacket material is preferred to protect against abrasion. The maximum sizes that the foot switches can accept can be found using the part specifications. Braided shielding is also an option to prevent electrical inference. Further, strain reliefs or cable gland seals can be used to seal the cable as it enters the foot switch. This can provide
mechanical protection by helping to anchor the cable into the foot switch and prevent the cable from exceeding its maximum bend radius.

How is the wire attached to the foot switch?
Many foot switches are available with screw terminals, solder terminals, or fast-on tabs to facilitate wiring, while some manufacturers offer pre-wire switches with standard or customized wire and/or cable.

What else might I need to know prior to my final selection?
Foot switches are available in a variety of pedal and housing colors. Colors often denote a particular function or process. For example, according to the IEC, YELLOW indicates “CUTTING” and BLUE indicates “COAGULATION.” Different housing colors can sometimes be ordered to match the ascetics of the machine or instrument.

What are the typical certification requirements?
Certification requirements vary by industry. IEC60601-1 is the typical standard for medical applications. There are also variations of this standard for HF surgical, x-ray, and laser equipment (for surgical, cosmetic, therapeutic, and diagnostic applications). Testing to these standards may be necessary depending on the type of equipment and application of the foot switch.

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Polycarbonate GEOS enclosure.

Non-Metallic Enclosures

Compared to Metallic Enclosures

What you want from your enclosure is long-term, productive service. Knowing your application and the environment in which it will be located will help, but understanding the materials available will complete your research so that you can make the right decision for your particular application.

Often in the design process, enclosure selection is one of the last things to consider. Alternately, the enclosure is selected up front, but based solely on what was used before or what is familiar and not what the application and environment might demand. There are many design engineers who believe that their only enclosure selections are between metal and plastic enclosures. This, of course, is only partly true.

When making the decision for purchasing the right enclosure for your application, there are a number of considerations to think about—besides environment, which includes corrosion resistance (see below), temperature, size, weight, and more. Other things to examine in your research include electrical safety, conductivity, and shielding properties; security access in the event of vandalism; cooling or heating requirements; the aesthetics of the device based on whether it will be visible or not; and the overall value and cost of the system when taking into consideration time in service and initial costs.


Outside application photo of polycarbonate enclosure.

Recommended Materials for Corrosive Environments





Highly Recommended

• Stainless Steel

• Fiberglass

• Fiberglass

• Stainless Steel

• Fiberglass

• Stainless Steel

• Aluminum

• Powder Coated Steel


• Polycarbonate


• Powder Coated Steel

• Polycarbonate

• Galvanized Steel

• Powder Coated Steel

• Galvanized Steel

Limited or Unacceptable

• Aluminum

• Galvanized Steel


• Aluminum

• Polycarbonate


The Basics of Metal Enclosures

Design engineers often think about purchasing metal enclosures first, based primarily on the idea that they are stronger and more durable than most other materials. This may or may not be the case dependent on the application but, more importantly, these considerations may not be necessary in the first place. For example, you may not need an enclosure that is durable if the components being protected are housed deep inside a piece of equipment that already has its own environmental control, and is not subject to the outside environment at all—think subsystems, additional Wi-Fi circuits, or an upgraded sensor system.

When considering some of the factors mentioned above, size and weight can be a bigger issue than simply protection. This is especially the case in many automotive, medical, marine, and agricultural applications where compactness and minimal weight are key features. Further, metal enclosures often require additional sealing to keep out moisture and water. They are mechanical in nature, requiring either hinges and doors or two sections that must be bolted or screwed together.

Corrosion resistance is an important item to think about when using metal enclosure materials. Most metals corrode, under particular conditions and at rates that depend on the type of metal used and the environmental conditions in which it is located. Consider the food and beverage industry where continual washdowns—often with detergents and chemicals— are part of the daily or weekly environment. Such regular abuses might preclude the use of company labeling and branding opportunities as well. Stainless steel and aluminum, for obvious reasons, are common choices for enclosure material, based on their high resistance to corrosion. When designing a system that will be used in harsh environments, these choices may provide you with reliable protection where other metals do not. Stainless steel enclosures are often highly expensive to purchase, making them difficult to purchase when project budget is an issue.
Strength and toughness can be a clear factor when deciding on the right enclosure. Strength is a measurement of the material’s resistance to failure. Toughness, on the other hand, measures a material’s ability to withstand sudden impacts. These two features work together, in that increasing toughness usually decreases strength and vice versa. When using a metal enclosure, such as stainless steel or aluminum you may get high strength, but units may dent easily, reducing the integrity of the box—and possibly breaking the sealing ability of the unit dependent on the type and material of the seal used.

For example, when an enclosure is not flush and the seal loses its properties, the enclosure is no longer water or air-tight; moisture and particulates are key reasons some electrical and electronics components fail. Plus, the internal controls and circuits can also become easier to access, reducing security of the system overall.

The Basics of Non-Metal Enclosures

Some of the most used materials for non-metal enclosures include polycarbonate, polystyrene, and ABS. It’s important to note that regular advancements are being made in plastics technology. What you may have found unavailable one year may be available the next.

When it comes to polycarbonates, some are available that feature UV stabilizers used to protect the material from sun overexposure. Others may include a formulation that includes glass fibers, which can significantly increase tensile strength, flexural strength, and flexural modulus, in addition to providing greater heat deflection for temperature sensitive applications.
Plastics are often more amenable than metals to be worked, molded, and modified to fit a specific application. This versatility allows such materials to be used in a wide variety of applications, because having flexibility in material components makes it easier to fit a specific need. Plastic enclosures have the added benefit of being lighter in weight, which makes them easier to handle and ideal for handheld devices, as well as for mounting on delicate surfaces such as sheetrock.

Some additional features that plastic enclosures make available: UV performance, broad temperature range, chemical resistance, waterproof, non-magnetic and electrical insulating, ease-of-processing, self- extinguishing flammability properties, and ease of modification. There are plastics that won’t dissipate harmful gasses in the event of fire, and there are some chemicals that react negatively to metals where plastic enclosures are more suitable. Note also that most often plastic enclosures are less expensive than metal enclosures and have shorter lead times, especially when semicustom or custom elements are needed.


Shown are stainless, aluminum and painted steel enclosures.

Consider the Application

Manufacturing control systems, as well as process control systems are often direct-wired and may depend on being RFI/EMI shielded from the electrical noise present in those applications. When a metal enclosure is used, the components inside are automatically protected against such outside interference, making the overall system robust in nature. This same shielding works well with other heavy machinery, such as equipment found in the machine tool industry. Such applications often have additional needs for chemical resistance.
For these types of applications, non-metal enclosures may need to have additional shielding to maintain a safe place for sensitive electronics. Further, such enclosures may need to have special seals or use particular materials that allow them to operate in the harsh environments of the factory floor. In either case, if the enclosure houses delicate electronic circuitry there may also be a need for cooling hardware to be installed. Metal and non-metal enclosures have their value (see below).

Since so much equipment and systems are being upgraded with wireless communications built into them, the enclosure market has had to keep up. When using metal enclosures, the user may need to install an external antenna in order to get optimal use from the system. If the environment dictates that a metal enclosure is necessary, be sure to also research any antenna network you plan to use with it to be sure that the antenna can also handle the harsh environment.

Consider that external antennas are often vulnerable to environmental elements, such as corrosion, ferrous oxide deterioration, and natural ambient interference from the environment itself. This may be the biggest reason why design engineers are switching to non-metal enclosures in communications applications: They allow for free transmission of electronic signals.
Because most non-metal enclosures enable electronic signals to transmit through the enclosure itself, the choice of enclosure material becomes more dependent on its ability to resist corrosion, tolerate the use of harsh chemicals, maintain a strong and tough exterior, and sustain its thermal capabilities. In addition, non-metal enclosures provide engineers with an attractive finis, and can be easily adjusted for changes added later. These include cutouts for additional access to the electronics, whether for quick security checks, to download information, or for audio/video connections. Non-metal enclosures have, over the years, proven to be durable, never rust or corrode in harsh environments, and provide secure and lockable lids to prevent unauthorized access. They are more resilient to impact (they give rather than dent) and allow wireless systems to easily operate without an external antenna. The one negative consequence of using metal enclosures is the compromise of the gasketed seal, which is extremely important to prevent moisture, dust, and other environmental factors from damaging internal controls. Non-metal enclosures usually have the seal inside a groove in the lid, which protects it from direct damage. All of this helps to explain why non-metal enclosures are frequently replacing metal enclosures in many applications.

Pros and Cons for Primary Metal and Non-Metal Enclosure Types

Metal Enclosure Types



Stainless Steel

• Corrosion resistant

• Impact resistant

• RFI/EMI shielded

• More expensive than low carbon steel or aluminum

Low Carbon Steel

• Inexpensive metal

• RFI/EMI shielded

• Requires coating to prevent rust

• Will rust if coating wears off


• Rust resistant

• Lighter than steel

• Lower impact resistance than steel

Non-Metal Enclosure Types




• Highly impact-resistant

• Nice appearance

• Allows for RFI/EMI transmissions

• More expensive than PVC, ABS, and Polystyrene



• Polystyrene

• Cheaper than polycarbonate

• Allows RFI/EMI transmissions

• Lower impact resistance

• Limited temperature range

Polymer-fiberglass composites

• Corrosion resistance

• Weight to strength ratio

• Allows RFI/EMI transmissions

• Blooming


In conclusion, remember that your application is the most important guide to what type of enclosure you will want to purchase. As mentioned, going with the same enclosure for every application typically isn’t the right path to take. When doing your research, find companies that have multiple options available, have been doing business for a long time, and have experience and expertise in how to select and implement enclosure technology. Enclosure needs, like other vital components inside your application, should be selected carefully and confidently.


An all-in-one DC UPS power solution
Murray Slovick

CBI Group Image

Figure 1: Altech’s CBI UPS power solution combines several applications in just one device.
Source: Altech Corp.

Altech’s CBI “all-in-one” UPS power solution offers a unique approach to backup power, combining several applications in just one device. It can be used as a power supply unit, a battery charger, a battery care module or a backup module.

Each device is suited for all common battery types: open/sealed lead acid, lead gel and Ni-Cd (Ni-MH and Li-ion batteries by means of jumpers). Other charging curves can be loaded into the device from a laptop.

While the available power is automatically split between the load and battery, supplying power to the load is always the priority. The maximum available current on the load output is twice the value of the device-rated current.

These units accept a wide range of input voltages, such as 120, 230 and 277 V AC, which makes the product usable anywhere in the world without any additional settings. A high voltage input version for 400 and 500 V AC is also available. Output voltages are assigned, or can be selected before installation for any voltage between 12 and 48 V DC.

Altech’s “Battery Care” philosophy is evident in the CBI series. This is based on algorithms that implement rapid and automatic charging, battery charge optimization, flat battery recovery and real-time diagnostics during installation and operation. Battery faults such as elements in short circuit, accidental reverse polarity connection and battery disconnection can easily be detected, identified and removed. Anomalies are indicated through a battery fault LED that provides a flashing code of the diagnosis.

Charging modes are also indicated by the LED:

■ Recovery (five blinks per second), able to recharge batteries even when their voltage is close to zero
■ Boost — Bulk (two blinks per second)
■ Absorption (one blink per second)
■ Trickle — Float (one blink per two seconds)

And it gets even better — much better if concerns include the risk of battery damage. CBI devices provide a high efficiency value of up to 91% through state-of-the-art switching technology and microprocessor-controlled battery charging. Microprocessor-controlled charging also means that the system is constantly monitored, reducing the risk of battery damage and allowing safe operation in permanent connection. Every 60 seconds the system checks battery connection; in trickle charge and every 220 minutes it tests battery efficiency. Continuously testing the internal impedance status avoids any possible risk of damage.

CBI power supplies can be paralleled for redundancy to obtain a higher system availability or to double the power of a single unit. It is possible to connect as many units in series as needed, providing the sum of the output voltage does not exceed 150 V DC. In operation, one unit is configured as Master and the other as Slave; user interface elements (jumpers, charging level trimmer, start button, thermal sensor and relays) must be used on the Master only, not on the Slave. In this configuration mode, only the Master device displays status via the LED indications.

If a device is disconnected from the main power source, or in case of mains failure, the battery will supply the load until battery voltage reaches 1.5 Vpc (volts per cell). Below this level the device automatically switches off to prevent deep discharge and battery damage.
In most cases the system can recharge deeply discharged batteries even when their voltage is close to zero, thus allowing for recharging and complete recovery of flat batteries. Load output will not be affected by battery conditions. The DC-UPS ensures continuous power supply to the load even in conditions of completely discharged batteries.

Altech’s communication platform uses a single protocol based on the CAN2.0 standard. This allows units to communicate with all the accessories provided by Altech at the same time. It allows monitoring and control of all parameters in the system, from anywhere in the world, by means of application tools on the cloud.

With a variety of battery chargers available on the market, it is important to choose a charger best-suited to a specific application. Altech’s CBI Series ensures high reliability with mean time between failures (MTBF) values of up to 300,000 hours. A rugged casing with bracket for DIN rail mounting provides IP20 protection (protected from touch by fingers and objects greater than 12 millimeters).

Visit the Altech website for more information on its microcontroller-based DC UPS solutions.

Click to learn more.

Not all Distribution Boxes are Created Equal

If sealed enclosures are used in environments with fluctuating temperatures and air humidity, condensation problems may arise as water vapor collects on the internal surface of the enclosure. If the enclosure, in turn, contains electrical equipment, the result is an increased risk of system malfunction due to short-circuiting, electrical and electronic component breakdowns or rusting and corrosion.

Depending on the power losses given off by the installed devices, the air inside an enclosure commonly heats up to temperatures of 55° C (133° F) or more. As this warm air inside an enclosure comes into contact with the enclosure’s colder casing, it cools and may chill to a point where it can no longer retain the same amount of water. Air at a certain temperature and a certain pressure can only absorb a certain maximum quantity of water vapor. For example, in comparison to a temperature of 55° C (133° F) air at a temperature of 20° C (68° F) can only absorb 20% of the water content.

These issues are magnified when enclosures are exposed to changes in temperature from daytime to nighttime and from sunny to shady conditions.

Sealed enclosures will not allow the air inside the enclosure to escape. As a consequence, water vapor, which is suspended as a gas, turns into liquid water. This is called the dew point — the atmospheric temperature (which varies according to pressure and humidity) below which water droplets begin to condense and collect inside the box.

Figure 1: Patented air ventilation system removes condensation from enclosure. Source: Altech

Figure 1: Patented air ventilation system removes condensation from enclosure. Source: Altech

Fortunately, technology can assist. In order to avoid the formation of condensation, the Altech AKIII Air enclosure is fitted with a patented air ventilation system comprised of an air ventilation element and drainage supporting the transportation of condensate out of openings in the enclosure.

In operation, there are two vents in the enclosure, one near the top of the enclosure and one near the bottom of the enclosure. This creates an air exchange that allows the hot air that builds up inside the enclosure to escape through the top. As the outside air temperature starts to cool down, it enters through the other vent; this steady air exchange transports the moisture out of the enclosure before the moist air starts to condense.

The ventilation element facilitates the avoidance of condensate while maintaining the high IP protection rating of IP65.

By way of review, IP65 enclosure characteristics include:

  • Complete protection from dust, oil and other non-corrosive material
  • Complete protection from contact with enclosed equipment
  • Protection from water, including water projected by a nozzle against enclosure from any direction

Figure 2: Filter element mounted inside the box removes 10 μm or larger particles. Source: Altech

Figure 2: Filter element mounted inside the box removes 10 μm or larger particles. Source: Altech

The AKIII enclosure is fitted with a filter element that retains particles that are 10 μm or larger. The filter is mounted inside the box and is exchangeable.

The ventilation system is maintenance-free by design and the enclosure is a UL-listed product with a NEMA 3R rating. NEMA 3R enclosures are typically used in outdoor applications for wiring and junction boxes. This style of enclosure provides protection against falling rain, sleet, snow and external ice formation. Additionally, it protects against dripping water indoors.

Altech’s AKIII is made of polycarbonate, which is a very durable engineered plastic material. Unlike steel, it is non-corrosive and it is resistant to harmful mechanical stresses, in particular impact stresses. It is a maintenance-free material that offers reliable protection and resistance to chemicals and can be expected to deliver long operational service with low installation expense.

Another feature is that the top and bottom end walls are supplied open and can be fitted with different types of flange mount end walls. This allows for many options for different types of knockouts or smooth walls. They can also be used to combine two enclosures (top to bottom) because there is a combination flange that can be used in place of end walls.

Figure 3: The AKIII series comes in a variety of enclosure sizes. Source: Altech

Figure 3: The AKIII series comes in a variety of enclosure sizes. Source: Altech

The interior of the AKIII serves to accommodate the equipment and is fitted with various mounting options depending on the variant. In all, there are seven different models. The difference among them is how much space they have for components. Four models are basically single-door, double-door, triple-door and four-door enclosures for circuit breakers or timers. The single door is a 14 circuit breaker enclosure. Similarly, the double door is 28, the triple door 42 and the four-door can hold 56 breakers.

In addition, three models called the Plus series are available with an extra mounting space in the top instead of a door. This is useful for mounting components that should not be visible, which can include all wiring or extra terminals that don't need access from the enclosure doors.

Height adjustable DIN rails are pre-installed for component mounting. Other accessories are available such as partitions, mounting tab kits, cable glands, etc.

For more information on the AKIII Air enclosures, visit Altech.

Safety for the Smart Factory

By: Murray Slovick

The new SRF (Safety RFID) is a non-contact safety sensor that monitors movable safety guards.

With the convergence of automation, wireless IoT and information technology, real-time data can be downloaded at any point in the production process to an on-site control room, an off-site data center or “the cloud.” The result has been an unprecedented level of manufacturing flexibility and efficiency. Collectively, this phenomenon is being referred to under various labels, including “smart factories,” the “fourth industrial revolution” or, simply, “Industry 4.0.”

To support the implementation of safe “smart” factories, Altech is introducing Bernstein AG’s non-contact Smart Safety Sensor. Designated SRF (an abbreviation of Safety RFID), it features an innovative diagnostic system that makes safety circuits suitable for today’s Industry 4.0 facilities.


Figure 1: The SRF provides a multitude of diagnostic data of each sensor,
even in a series connection, to support smart production. Source: Bernstein AG

But we are getting ahead of the story. It all starts with non-contact radio frequency identification (RFID) coded safety switches that monitor the opening and closing of machine guards, doors or fences. Safety guards, of course, prevent operator access and must therefore be kept closed until the hazards posed by machine movement have ceased, protecting personnel around machinery and other equipment. RFID is itself not new to manufacturing — it has been used throughout the supply chain for many years, especially in inventory control and asset management. Applied to safety equipment, however, RFID provides tamper-proof protection and simplifies installation as physical contact is not required between the switch and the actuator; the sensor itself can even tolerate some misalignment.

The new Bernstein AG smart sensor SRF is well-suited for any location where safety switches are in use. It is an ISO 14119-compliant type 4 product (an interlocking device with non-contact position switches and a coded actuator). ISO 14119 defines possible methods for selecting and installing safety switches and sensors and further defines possible methods used to prevent tampering such as the use of coded actuators to avoid any actuation of the locking system by readily accessible objects.

Consequently, the SRF is ideal for utilization scenarios involving packaging machines and equipment, woodworking machines, turning and milling machines, food processing machines and injection molding machines, to name just a few.


Figure 2: The SRF can be used in a variety of industry sectors, including but not limited to packaging,
woodworking, milling and lathe, food and injection molding. Source: Bernstein AG

This particularly compact sensor (featuring a 3.5 mm x 26.2 mm x 1 mm housing) protects employees from injuries by signaling the safety monitor (via two OSSD outputs) to shut down or disable the startup of machines when the safety guard is not properly closed. It monitors movable safety guards such as hatches, doors, flaps, hoods and protective fences, ensuring that safety doors and protective guards remain closed when danger is present. The SRF monitors the position of the guards using a coded sensor, which can only be used in conjunction with a specific Bernstein AG actuator designated for this purpose. The actuator has a non-modifiable safety code for error-free identification. This code is submitted to the SRF sensor and is permanently saved in the SRF, without any additional equipment required. Three different coding levels are available:

  • Low (L): The SRF accepts any Bernstein AG actuator.
  • High (H): The SRF accepts only the taught-in actuator (SRF-0), a maximum of 12 teach-in processes are possible.
  • Unique (U): Similar to “High,” but only one teach-in actuator process is possible.


The SRF adheres to ISO 14119, a standard that covers mechanical or electrical devices that are designed to prevent the operation of a machine element for as long as the movable safety guard is left open. ISO 14119 determines which coding level is required.

The Value of Diagnostics
In developing this new product, Bernstein AG paid particular attention to the diagnostic system accompanying the sensor. In addition to the safety outputs, all the switches have an extra diagnostic output. The system provides a large amount of data, making it available centrally and flexibly as an aid to intelligent production.

Called the daisy chain diagnostic (DCD) system, it submits a complete status image of a sensor, even in series connection to support smart production. The diagnostic interface is located between the last sensor and the safety controller. Even in case of power supply shutdown, the diagnostic error memory can be read, which allows quick troubleshooting.


Figure 3: Daisy Chain Diagnostics make the machines more efficient and
enable predictive maintenance to be realized. Source: Bernstein AG

The higher-end switches use a bus system within the series line that can be used to communicate via IO-Link to a PLC or PC, to an Android smartphone via NFC (near-field communication) interface or via USB for displaying sensor information on a PC or laptop. In all, 20 different diagnostic information elements from each sensor can be retrieved and made available. The following information, among others, can be transmitted: opened door, detection of misalignment (warping of the door), detection of under-voltages in the series connection and attempts to defeat the SRF unit.

Data collected in this manner can be used for predictive maintenance based on early fault detection, possibly preventing a costly shutdown. Even in cases of power supply shutdown, the diagnostic error memory can still be read. Simpler switches in the product line use PNP diagnostics, which can be used to communicate directly with most PLCs.

Since we have mentioned series connections twice, some explanation is in order: the new SRF can be used individually or in series. This is important because basic magnetic switches typically cannot be run safely in series. Since there is no mechanical connection between the actuator and switch (like might be found with a keyed interlock switch), welded or broken contacts (typically reed switches) may not be detected when the door, gate or panel is opened, creating a dangerous condition. Normal magnetic switches typically require a cable to be run from each switch back to a dedicated isolated special safety relay input.

In a single-use SRF application, a movable safety guard is monitored through one SRF. The two OSSD safety outputs of the SRF are connected to a safety monitoring unit. In a series connection, several movable safety guards are monitored. The safety outputs of the last SRF are connected to a safety monitoring unit. After closing all safety guards (all actuators detected), the last SRF of the series connection switches on the safety outputs.

The SRF system features “plug-and-play” wiring — the switches use M12 connectors to plug into series “T” connectors — making installation very simple and fast and saving a great deal of labor and installation time. Switches can also be easily added or removed from the series run by simply plugging in or unplugging components. Using unshielded four-wire standard cable and standard plugs reduces wiring cost.

Fault Tolerant Outputs

The fault tolerant outputs prevent an unexpected machine stoppage. There is no shutdown in case of one output error (there is immediate shutdown when a second fault occurs). Faults that do not immediately compromise the safe operation of the SRF (e.g., external short circuits) result in a delayed switch-off of the safety outputs. The safety outputs will switch off when the error warning exceeds 20 minutes. If an error is detected at one output, the sensor indicates this with a flash code — while simultaneously transmitting the information via the DCD system. These features can be used to shut down the machinery in a controlled manner. The safe outputs enable and allow a restart.
About the Suppliers

Altech Corp. is an established United States supplier of components and devices used in industrial control, instrumentation, medical and automation applications. The company provides a very broad line of products that meet UL and international standards and are RoHS and REACH compliant. A sample (non-exhaustive) list of their products includes circuit protection devices, contactors, DC-UPS solutions, digital timers, DIN enclosures, fuses and fuse holders, foot switches, industrial enclosures, interface modules, meters, motor disconnect switches, pin and sleeve devices, power supplies, push buttons and pilot lights, relays, safety switches, sensors, and test and measurement equipment. Altech’s commitment to quality management has been recognized since 1999 when the company was awarded ISO 9001 certification. For more information, visit
Bernstein AG is renowned for the development and marketing of safety switches, sensors and enclosures. Based in Porta Westfalica, Germany, its focus is on protecting the operator through machine and process safety through use of a comprehensive product program that fully meets relevant safety requirements across a wide range of specific applications. The family-owned and managed company celebrated its 70th anniversary in the summer of 2017.

Non-Metallic Enclosures Offer Clear Benefits in Agriculture
Bill Schweber

Electrical and electronic cable, connectors and related subsystems need rugged enclosures for the harsh agricultural environment, where non-metallic enclosures offer distinctive benefits compared to conventional units.

It is well-known that many industrial installations and production facilities are often harsh settings, with oil, dirt, vibration, physical abuse and other numerous issues. In contrast, many people envision an agricultural setting as crops in the field, often with animals quietly grazing or resting in their barn. The image is all peaceful and benign (Figure 1).

Altech Agriculture Enclosures

Figure 1. A farm may seem a quiet and clean operation compared to an industrial facility, but it is actually more challenging in terms of dirt, dust, waste, impact and corrosive environment. Source: Altech

Despite this image, the reality is quite different — and it is a harsh one.

A modern agricultural operation can be as bad as or even worse than an industrial environment. There are constant dirt, crop dust and discards, physical impact, extreme temperatures (both hot and cold), extreme weather (storms, flooding) and more. Further, unique to the farm environment is the presence of animal waste (primarily ammonia), which is corrosive to many materials.

Therefore, rugged enclosures are needed to enable effective and reliable modern farm work. These enclosures house and protect electrical lines, lighting controls, switchgear, safety and security wiring, even sophisticated electronics; they are also critical for user and livestock safety.

Enclosure Considerations Define Selection

The common solution is to select a suitable metallic enclosure, either steel or aluminum, to provide the needed ruggedness and protection. However, in the case of farms, a non-metallic polycarbonate enclosure (Figure 2) can be the better choice, as it resists moisture, corrosion, chemicals and even ammonia.

Altech Agriculture Enclosures

Figure 2. Non-metallic polycarbonate enclosures, such as the dust- and moisture-proof TK and TG series from Altech Corp. offer many useful performance advantages and attributes in the farm/agriculture environment, as compared to metallic units. Source: Altech

Polycarbonate enclosures offer other advantages in addition to basic ruggedness. Obviously, they are rust-proof and have no surface finish that can wear or chip, thus allowing rust to take hold. Further, these non-metallic units meet various relevant standards, among them:

  • UL94 (Flammability of Plastic Materials);
  • NEMA IP66/67 (particle and water ingress);
  • VDE 0471 (fire hazard);
  • IK07 (impact);
  • Wide operating-temperature range of -35 degrees C to +80 degrees C.

A special feature of polycarbonate enclosures is that they can tolerate high concentrations of ammonia, meeting the stiff certification requirements of the German Agricultural Society (Deutsche Landwirtschafts-Gesellschaft, or DLG). They can withstand an ammonia concentration of 750 ppm (parts per million) at 70 degrees C and 70 percent humidity over 1,500 hours of continuous testing.

Customization Opportunities Make an Additional Difference
While the physical sizes of polycarbonate enclosures are standardized, this is not a serious constraint, as they are available in a wide range of height, width and depth dimension combinations. Once a basic enclosure is chosen, many attributes and features can easily be customized. Vendors can do value-added work to reduce end-user effort even for moderate volumes, typically beginning at just 25 units (Figure 3). Among these are:

  • Choice of hinge type (internal, external);
  • Choice of mounting style and orientation;
  • Panel cutouts for displays, indicators, keypads and other functions;
  • Pre-packaged connectors and pushbuttons;
  • Imprinting and labeling;
  • Choice of transparent or opaque cover.

Altech Agriculture Enclosures

Figure 3. Non-metallic polycarbonate enclosures are offered with many standard options as well as customizable options. Source: Altech

Polycarbonate Enclosures: An Attractive Alternative
Non-metallic polycarbonate enclosures can be a superior and flexible match for harsh applications such as agriculture, especially due to their corrosion and ammonia resistance. They meet and exceed all
relevant industry standards for corrosion, impact resistance, ingress protection, flammability and more. Further, the vendor can customize many aspects of these enclosures to meet specific user requirements and preferences.

For more information on choosing and using non-metallic polycarbonate enclosures, contact Altech Corp.




Altech UL98 Disconnect Switches

UL98 Open & Enclosed Disconnect Switches

60 A & 100 A

Altech now offers new UL98 Open and Enclosed 60A & 100A Disconnect Switches. One design used in direct and extended handle applications.


One design used in direct and extended handle applications

Horsepower rated

Enclosed switches are available in plastic, sheet metal and stainless steel enclosures

Every design is lockable in OFF position

Switching mechanism speed is independent from the operator

Silver contacts ensure safe and durable operation

Accessories include add-on 4th/neutral pole, auxiliary switches, shafts, door interlock handles and touch protectors

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For more information contact Altech at:
908-806-9400 • 908-806-9490 (FAX) • • 35 Royal Road, Flemington, NJ 08822