Terms & Conditions
Frequently Asked Questions
What is a Zig-Zag Grounding Transformer?
A Zig-Zag grounding transformer is a special three phase autotransformer with no secondary or output. It is used to establish a neutral on a 3 wire system. There are several reasons why a zig zag autotransformer may be used include ground fault protection, neutral grounding (solid or via a resistor), and harmonic filtering.
What is an Isolation Transformer?
All transformers other that autotransformers are Isolation Transformer. This is due to the fact that the primary and secondary windings are electrically isolated from each other (they are not physically connected to each other). The transformation in voltage and current between primary and secondary windings occurs as a result of the shared magnetic field in the core (Mutual Inductance).
What is an Autotransformer?
An autotransformer is a transformer that has only one winding per phase, part of which is common to both the primary and secondary circuits. Transformers wired in a “Buck-Boost” configuration are autotransfomers. Autotransformers are designed to adjust the supply voltage when isolation from the line is not necessary and where local electrical codes permit. An autotransformers can be used in either a step-up or step-down application unlike isolation transformers. Autotransformers can also be used as part of a reduced voltage starter to reduce motor inrush current (see Motor Starting Autotransformers)
What are the standard service conditions for a dry type distribution transformer?
Unless designed for special service conditions / environments, below are the standard service conditions for dry type distribution transformers:
- Ambient Temperature: -40°C to + 30°C (max peak +40°C)
- Relative Humidity: < 70%
- Altitude: ≤ 1000m ASL (3300 ft.)
Avoid rain, moisture, high temperature, intense heat or direct sunlight. Maintain the minimum recommended clearances and ensure that all ventilated panels are clear of obstructions.
What is temperature rise?
Temperature rise refers to average increase of temperature of the transformer windings at full load above the ambient temperature. These is also a “hot spot” temperature, which refers to the hottest temperature at any specific point in the transformer winding. For example, distribution transformer with a 220°C insulation system would typically be designed with a 150°C average temperature rise and a + 30°C hot spot allowance. Above a 40C ambient, the total absolute temperature will not exceed 220°C. Transformers with lower temperature insulation systems (180°C or 200°C) will be designed with lower temperature rises (115° or C130°C) and hot spots so they can be installed in the same ambient temperature and still not exceed the temperature rating of the insulation system. See table below with the maximum average winding temperature rise, maximum hot spot temperature rise and maximum winding temperature for the most common insulation ratings. Note that these are based on a max average ambient of 30°C during any 24-hour period and a maximum ambient of 40°C at any time.
Insualation Rating | Insulation Class | Average Winding Temperature Rise |
Hot Spot Temperature Rise |
Maximum Winding Temperature |
Class 180 | F | 115°C | 145°C | 180°C |
Class 200 | N | 130°C | 160°C | 200°C |
Class 220 | H | 150°C | 180°C | 220°C |
Customers often request lower than the average temperature rise values shown in the table above. The lower average temperature rise can offer the following benefits:
- The transformer can be installed in higher ambient temperatures without overheating beyond what the insulation is designed for.
- The transformer can be expected to have a longer operational life with lower MTBF.
- The transformer can handle continuous overloads and higher short time overloads without overheating beyond what the insualation is designed for.
What are the storage requirements for a dry type transformer?
Any transformer which is not installed and energized immediately should be stored in a dry, clean space having a uniform temperature to prevent condensation on the windings. Dry type transformers with resin dipped or epoxy vacuum impregnated coils can be stored at ambient temperatures as low as -50C. Transformers with encapsulated or epoxy cast coils should not be stored at ambient temperatures below -20C to prevent cracking of the epoxy. Preferably, transformers should be stored in a heated building having adequate air circulation and protected from cement, plaster, paint, dirt, and water or other gases, powders, and dust. The floor on which the transformer is being stored should be resistant to the upward migration of water vapor. Precautions should be taken to prevent storage in an area that water could be present, such as roof leaks, windows, etc. Condensation or absorption of moisture can be greatly reduced by keeping the transformer enclosure 5⁰C-10⁰C above ambient temperature. This can be easily achieved by the installation and energization of space heaters (optional). If the transformer is not furnished with internal space heaters, then external, portable heaters can be used. Note: Lamps or heaters should never come in direct contact with the transformer coil insulation.
It is not advisable to store a dry type transformer outdoors, but in the case that it is unavoidable, protective measures should be taken to prevent moisture and foreign debris from entering the transformer enclosure. The plastic wrapping supplied during shipment should be left in place, and a suitable drying agent such as silica gel packs should be used. The unit should also be checked periodically for indications of condensation on the windings, coil support blocks, core, core clamping system and bus/cables.
What is required clearance around a dry type distribution transformer?
The minimum required clearances of a dry type transformer to walls, floors or other equipment must adhere to the local electrical code requirements.
In the absence of such requirements, Rex Power Magnetics recommends that dry type transformers be mounted so that there is an air space of no less than 150mm (6”) between the enclosures, and between the enclosure and any adjacent surface except floors. When the adjacent surface is a combustible material, the minimum permissible separation between the transformer enclosure and the adjacent surface should be 300mm (12”). Where the adjacent surface is the wall on which the transformer is mounted, the minimum permissible separation between the enclosure and the mounting wall should be 6mm (0.25”) so long as the surface is of a non-combustible material.
What do I need to consider for transformers energized at low ambient temperatures?
In Dry Type Transformers, the air inside and surrounding the enclosure are a critical part of the transformer’s function. Low ambient temperatures generally do not adversely impact an energized transformer, as the energization (no-load) losses typically generate enough heat to maintain appropriate conditions, in low ambient temperatures as low as -40 °C.
There are two main issues with energizing transformers which have been stored at low ambient temperatures:
- The insulation in the coils can become brittle at low temperatures. The expansion of the conductors after loading a transformer from a cold start, or the contraction of the conductor during storage at lower temperatures can lead to a crack in the insulation between turns or between layers, leading to an internal fault.
- Low ambient temperatures can lead to condensation forming within the transformer enclosure, as well as on and inside the transformer coils. Energizing a transformer with condensation on the coils can result in an internal fault and damage to the insulation.
Rex's installation, operation and maintenance manuals recommends that transformers be tested (meggered), brought above 0°C and/or go through a dry-out process if moisture is suspected to be present. Refer to REX's cold start procedure when energizing a transformer below 0 °C. Damage and injury can result from energizing a transformer which has had its insulation system compromised due to moisture.
What is the terminal temperature rating of ventilated dry type distribution transformers?
Rex Power Magnetics’ ventilated distribution transformer terminals are rated 90°C. Conductors with at least a 90°C insulation rating at or below their 90°C ampacity rating should be utilized.
What is the odor emitting from my new transformer?
It`s normal for new transformers to release some harmless odors from the varnish impregnation used in the coils for a week or two after energization. Older Transformers can also release some odor if loaded to a higher level than they have experienced previously in their history.
What is the life expectancy of dry type transformers
The minimum life expectancy of a dry type transformers is primary dependent on the insulation life vs. temperature relationship, designated as minimum life expectancy in IEEE Std C57.12.56. Other factors such as humidity/condensation, short circuit events, sustained overloads, and other external factors can cause a dry type transformer to fail prematurely, however those are outside the normal operating conditions of the transformer and are not considered in the design life expectancy.
Aging or deterioration of insulation is a function of time and temperature and described in detail in IEEE Std. C57.96. Since, in most transformers, the temperature is not uniform, the part that is operating at the highest temperature will ordinarily undergo the greatest deterioration. Therefore, aging studies consider the aging effects produced by the highest temperature.
Based on the insulation life expectancy curves outlined in IEEE Std C57.96, all of Rex Power Magnetics’ dry type transformers utilize a UL listed insulation system with a maximum hot spot temperature that will provide a design life expectancy of a minimum of 30 years under continuous rated load, and standard ambient temperature conditions. For transformer with a reduced average and hot spot temperature rise, this design life expectancy exceeds 50 years.
Can a transformer be connected in reverse (back fed)?
In general, dry type transformers can be connected in reverse (back fed) however there are several precautions that should be considered:
- Compensated Windings: Control transformers and distribution transformers below 3kVA are typically designed with an overvoltage on the secondary to compensate for voltage regulation at full load. Reverse feeding these transformers may lead to a lower than expected output voltage.
- Inrush current: The inrush current when energizing a transformer from the intended secondary terminals will be significantly higher than on the primary side as a multiple of the rated current. This high inrush current can cause nuisance tripping of the protective breaker and special considerations may need to be made.
- Voltage Taps: Given that there are typically no voltage adjustment taps on the secondary side, the transformer cannot be adjusted to account for higher or lower than nominal incoming voltages. In order to not damage the insulation or overexcite the core, the input voltage should not exceed the nominal rated voltage. Under voltage conditions are ok, and the taps on the primary winding can be used to boost the output voltage
- Grounding: When the secondary (wye) of a delta-wye transformer is energized instead of the primary (delta), then the wye side of the transformer is not a separately derived service. As such, the neutral should not be connected to building ground nor should it be bonded to the transformer enclosure
Always review applicable codes and standards and consult with the local authority having jurisdiction before reverse feeding transformers.
R.C. Snubber
Product Overview & Application
R.C. snubbers are a passive electrical devices, comprised of appropriately selected resistors and capacitors, which are used for protecting medium voltage power transformers from electrical switching transients. While lightning arresters help protect the transformers from the high voltage spikes that appear on the line after a lightning strike, snubbers are better suited for the more common problem of circuit breaker switching transients. Examples of the switching operation include instances where a circuit breaker switches between transformer primaries, or automatically triggered switching between grid and reserve power.
When a circuit breaker interrupts current flow, an arc develops across its contacts. The rapid current interruption usually occurs somewhere other than the current zero-crossing point, giving rise to a Transient Recovery Voltage (TRV), which has significant high-frequency content. If the transients are at the natural resonance frequency of the system, then there is a possibility of internal oscillatory voltages developing in the primary windings of the transformer. A high turn-to-turn voltage will result, which will lead to damage of the insulation.
The problem is further exasperated with modern vacuum-type circuit breakers, which have shorter distances between contacts. This serves to increase the speed of the interrupting cycle. The transient level and frequency are functions of the physical distance between the breaker and transformer, transformer construction, the type of load being switched, and the switching characteristic of the breaker.
The RC-snubber network lowers the frequency of the transient voltage applied to the transformer primary below the resonance frequency of the circuit. It reduces the development of the oscillatory voltages and provides a low impedance path to ground for the transients.
Snubbers are a low cost means for protecting a transformer against a costly repair and related downtime. In designing medium voltage power systems, it is a good practice to at least leave space for future installation of a snubber network.
Product Specification
Voltage Class | 2.4kV to 34.5kV (150kV BIL) |
Frequency | 60Hz (50/60Hz Optional) |
Fuse | 6A Full Range Current Limiting Fuse |
Resistor | 20 - 50 Ohm (+/- 10%) Tubular Non-Inductive Resistor |
Capacitor | 0.13uF, 0.25uF, 0.5uF Surge Capacitor |
Enclosure Type | Type 1 Indoor |
Enclosure Finish | ANSI/ASA 61 Grey |
Mounting | Floor Mounting |
Warranty | 12 Months (See Warranty and Limitations) |
Quality System | ISO 9001:2015 Quality Management System |
Optional Features & Accessories |
|
Documentation
Installation, Operation and Maintenance Manual (English) | |
Installation, Operation and Maintenance Manual (French) | |
Product Guide Specification (English) |
Canadian Sales Representatives
Alberta
Northern Alberta
Brodwell Industrial Sales7 Rowland CresSt.Albert ,AB T8N 5B3 Tel: 780.458.1500https://www.brodwell.com
Southern Alberta
Brodwell Industrial Sales#1010, 4385 104 Ave SECalgary, AB T2C 5C6
Tel: 403.253.7702https://www.brodwell.com
British Columbia
1424 Regan Ave
Coquitlam, BC V3J 3B5
http://www.arbutuswest.comE-mail: sales@arbutuswest.com
Tel: 604-521-5180
Manitoba
301 E Weston Street
Winnipeg, MB R3E 3H4Tel: 204-694-1339E-mail: info@IntegraAgencyltd.mb.cahttp://www.integraagencyltd.mb.ca
New Brunswick
32 McQuade Lake CrescentHalifax, NS B3S 1G8
Tel: 902-450-5155http://www.elp.ns.caE-mail: quotesind@elp.ns.ca
Newfoundland & Labrador
140 Cambell Avenue
St.John's, NL A1E 2Z8
Tel: 709-753-6685http://www.vigilanttechnicalsales.caE-mail: matt@vigilanttechnicalsales.ca
Northwest Territories
Tel: 906-695-8844 ext: 2351Toll Free: 1-800-387-2840 ext: 2351E-mail: sales@arexpowermagnetics.com
Nova Scotia
32 McQuade Lake CrescentHalifax, NS B3S 1G8
Tel: 902-450-5155http://www.elp.ns.caE-mail: quotesind@elp.ns.ca
Nunavut
Tel: 906-695-8844 ext: 2351Toll Free: 1-800-387-2840 ext: 2351E-mail: sales@arexpowermagnetics.com
Ontario
Southern Ontario
Ontech Sales Inc.1892 Baseline Rd. W.
Courtice, ON L1E 0X6Darrell Mcneill: djmcneill@rogers.com
Tel: 416-576-5114 Lynn Konowal: lynnkonowal@rogers.com
Tel: 905-828-4730
Northern Ontario (Thunder Bay, Ft. Francis, Terrace Bay)
Integra Agencies301 E Weston StreetWinnipeg, MB R3E 3H4
Tel: 204-694-1339http://www.integraagencyltd.mb.ca
Prince Edward Island
32 McQuade Lake CrescentHalifax, NS B3S 1G8
Tel: 902-450-5155http://www.elp.ns.caE-mail: quotesind@elp.ns.ca
Quebec
Québec - Estrie, Centre du Québec & Mauricie
Agence Béliveau Turmel et Associés57 Chemin MountainBolton-Est, QC J0E 1G0www.agencebta.com
Tél: 450-532-3578
Cell: 819-239-6591
E-mail: jean-francois.despres@agencebta.com
Québec - Rive-Sud de Montréal, Abitibi
Eric TurmelTél: 450-349-7453
Cell: 514-515-7453
E-mail: eric.turmel@agencebta.com
Québec - Montréal, Laval, Laurentides, Outaouais & Lanaudière
Eric MasséCell: 514-247-1909
E-mail: eric.masse@agencebta.com
Québec - Québec, Saguenay, Cote-Nord, Beauce, Gaspesie & Bas St-Laurent
Serge MaheuCell: 418-933-4513
E-mail: serge.maheu@agencebta.com
Québec - Coordonnateur Technique
Stephane Brouillette
Cell: 438-300-8801 #101
E-mail: stephane.brouillette@agencebta.com
Québec - Support Interne
Yanick TurmelTél: 438-300-8802 #106
E-mail: yanick.turmel@agencebta.com Chanel Fournier
Tél: 438-300-8802 #109
E-mail: chanel.fournier@agencebta.com
Saskatchewan
2717B Wentz Ave.Saskatoon, SK S7K 4B6
Tel: 306-653-0313https://www.advanceagency.netE-mail: sales@advanceagency.net
Yukon
Tel: 906-695-8844 ext: 2351Toll Free: 1-800-387-2840 ext: 2351E-mail: sales@arexpowermagnetics.com
AC Line / Load Reactor
Inductors placed at the input and output of electrical equipment can provide protection and improve performance. Line Reactors absorb many power line disturbances which could damage or shut down your inverters, order variable speed controllers, or other voltage-sensitive equipment.
Read more: AC Line / Load Reactor
General Purpose Isolation Transformer
General Purpose Isolation transformers are used to lower distribution voltages (480 or 600V) to lower voltages (typically 120/240 or 208Y120) for power distribution within commercial or industrial buildings. These “two windings” transformers provide the electrical isolation required, and allow for short runs of high current, low voltage cables, reducing losses in the system, and reducing costs.
Read more: General Purpose Isolation Transformer
Mini Power Center
Mini Power Centers combine three individual components, prewired into one NEMA 3R enclosure: a primary main breaker, a single-phase or three-phase dry-type encapsulated transformer (Type EP), and a secondary distribution load center with main breaker. Inter-connecting wiring is completed at the factory. Mini Power Centers are used wherever there is a 480V or 600V distribution system and loads requiring 208Y/120V, three-phase or 120/240V single-phase.
Autotransformer
Autotransformers are transformers which have a single winding per phase, part of which is common to both primary and secondary circuits. Using an Autotransformer is an economical and compact means of connecting electrical equipment to a power supply or a different voltage. Part of the winding is common to both primary and secondary circuits so there is no isolation between the two. This may be acceptable on some power systems that do not have a grounded neutral on the secondary side of the main power transformer. Typical applications include motor loads of industrial machinery, electric heating, air conditioners, etc. Designed for installation where a reliable power source is required for lighting and other low voltage equipment and machinery. Indoor and outdoor installation is possible depending on the enclosure.
Industrial Control Transformer
Industrial control transformers are used to convert the available supply voltage to the voltage that is required to supply industrial control circuits and motor control loads.
These loads consist of a combination of electromagnetic devices such as solenoid operated valves, switches, bells, alarms, and other components such as indicator lights, timers, electronic equipment, and logic boards.
Some components of a circuit, especially electromagnetic devices require a very high level of power at start-up. This start-up power requirement is called inrush VA. After their initial start-up, these components settle down to a lower power requirement for normal continuous operation. This lower operating power requirement is called Sealed or Steady State VA. Some devices can draw up to 10 times the normal operating or sealed current for periods of up to 50 milliseconds upon start up.
Control transformers must be designed, constructed, and selected to ensure that they provide the output voltage stability needed for trouble free operation of all circuit components.
Rex control transformers incorporate several features to optimize output voltage stability and regulation when supplying industrial control circuits with high inrush current requirements.
Read more: Industrial Control Transformer
Harmonic Mitigating Transformer
Harmonic Mitigating Transformers (HMT's) are specially designed for non-linear loads which draw significant amounts of harmonic current. While K-factor rated transformers are simply designed to handle the additional losses of supplying non-linear loads, HMT's actually minimize the voltage distortion and power losses that result from harmonic load currents.
Read more: Harmonic Mitigating Transformer
Encapsulated Transformer
Encapsulated (Potted) Transformers (also referred to as Epoxy Resin Encapsulated) are designed for applications where the enviromental conditions would not permit a general purpose ventilated dry type transformer. The entire tranformer core & coil is encased in a silica sand / polyurethane mixture which protects the windings from any airborne contaminants and moisture.
Read more: Encapsulated Transformer
Cast Coil Power Transformer
Cast coil power transformers feature primary and secondary windings which are vacuum cast inside a solid block of epoxy resin. The epoxy resin is introduced under vacuum in order to penetrate all the spaces within the winding, ensuring a void free casting with minimal partial discharges. The sold casting provides the highest degree of protection to the windings, making them ideally suitable for harsh environmental conditions which include airborne dust & high humidity. Furthermore, the fiberglass reinforcement which is incorporated into the casting provides the transformer with the highest mechanical strength which makes it resilient to short circuit forces.
Read more: Cast Coil Power Transformer
Motor Guarding Transient Filter
The steep voltage wave fronts of the Pulse Width Modulated (PWM) output of Adjustable Frequency Drives (AFD’s) produce high frequency effects which may damage the insulation of motors operated by the equipment. The problems result from two distinct effects.
Read more: Motor Guarding Transient Filter
Air Core Reactor
ir-Core reactors provide a linear impedance with respect to current which is crucial in many applications where an iron core reactor would otherwise saturate.
Control Power Transformer
Product Overview & Application
Medium Voltage Control Power Transformers (CPT) are single phase transformers used to supply control power in medium voltage switchgear and transformers. Nominal primary voltages range from 2.4kV to 15kV. The secondary voltage is typically configured for 120/240V (series parallel) operation. Note: Fuse and fuse clips shown in image are optional accessories.
Product Specification
Capacity | 500VA to 3,000VA Single Phase |
Voltage Class | up to 7.2kV (45kV BIL) |
Cooling | Self Cooled (ANN / AN) |
Frequency | 60Hz (50/60Hz Optional) |
Conductors | Copper (Cu) Windings |
Insulation System | 180°C (115°C rise) |
Enclosure Type | Open Construction With Encapsulated Coil |
Warranty | 12 Months (See Warranty and Limitations) |
Quality System | ISO 9001:2015 Quality Management System |
Certifications |
|
Reference Standards |
|
Optional Features & Accessories |
|
Documentation
Drawings
Drive Isolation Transformer
Drive Isolation Transformers are designed for supplying power to SCR (Silicon Control Rectifier) motor drives which provide convenient variable speed motor control and can save on energy. Unfortunately, the drawback of these variable frequency drives (VFD) is that they produce harmonic voltage distortion and draw harmonic currents from the source which can be damaging both to the transformer supplying the power, and the other equipment that is connected to that supply.
Read more: Drive Isolation Transformer
VPI/VPE Power Transformer
Vacuum Pressure Impregnated (VPI) power transformers utilize an open winding design, where the coil insulation is impregnated with an epoxy resin under vacuum and pressure, providing the windings a degree of protection against moisture and dirt, and improving the thermal conductivity of the winding which reduces localized hot spots. Furthermore, the VPI process removes air voids which deep within the windings, filling them with epoxy instead. These air voids, if not eliminated, can lead to higher partial discharges which can damage the transformer insulation over time, leading to premature failure. For a higher degree of protection, vacuum pressure encapsulated (VPE) coils can be utilized which involves repeated VPI and bake cycles
Read more: VPI/VPE Power Transformer
Encapsulated Transformer Enclosures
NEMA 3R Enclosures For Encapsulated Transformers (3 Phase)
Enclosure Size |
Width (in) |
Depth (in) |
Height (in) |
Weight (lbs) |
Downloads |
E3R-3PEP-1 | 11.00 | 10.00 | 15.25 | 23 | |
E3R-3PEP-2 | 15.00 | 11.00 | 15.25 | 33 | |
E3R-3PEP-3 | 18.00 | 12.50 | 17.00 | 41 | |
E3R-3PEP-4 | 21.00 | 14.00 | 17.50 | 49 | |
E3R-3PEP-5 | 21.00 | 18.00 | 20.00 | 68 | |
E3R-3PEP-6 | 26.00 | 18.00 | 25.00 | 85 | |
E3R-3PEP-7 | 32.00 | 18.00 | 30.00 | 114 | |
E3R-3PEP-8 | 36.00 | 25.00 | 32.00 | 154 | |
E3R-3PEP-9 | 36.00 | 25.00 | 36.00 | 167 |
NEMA 3R Enclosures For Encapsulated Transformers (1 Phase)
Enclosure Size |
Width (in) |
Depth (in) |
Height (in) |
Weight (lbs) |
Downloads |
E3R-1PEP-1 | 5.25 | 4.50 | 11.00 | 4 | |
E3R-1PEP-2 | 6.00 | 5.25 | 12.00 | 5 | |
E3R-1PEP-3 | 7.50 | 6.50 | 13.50 | 8 | |
E3R-1PEP-4 | 12.50 | 12.50 | 15.00 | 33 | |
E3R-1PEP-5 | 15.00 | 15.00 | 18.00 | 43 | |
E3R-1PEP-6 | 18.00 | 14.00 | 25.00 | 57 | |
E3R-1PEP-7 | 19.00 | 16.00 | 28.00 | 68 | |
E3R-1PEP-8 | 25.00 | 20.00 | 33.00 | 100 | |
E3R-1PEP-9 | 25.00 | 22.00 | 36.00 | 110 |
NEMA 4 Enclosures For Encapsulated Transformers (3 Phase)
Enclosure Size |
Width (in) |
Depth (in) |
Height (in) |
Weight (lbs) |
Downloads |
E4-3PEP-1 | 11.00 | 12.00 | 15.25 | 29 | |
E4-3PEP-2 | 15.00 | 13.00 | 15.25 | 37 | |
E4-3PEP-3 | 18.00 | 14.50 | 17.00 | 48 | |
E4-3PEP-4 | 21.00 | 16.00 | 17.50 | 62 | |
E4-3PEP-5 | 21.00 | 20.00 | 20.00 | 73 | |
E4-3PEP-6 | 26.00 | 20.00 | 25.00 | 95 | |
E4-3PEP-7 | 32.00 | 20.00 | 30.00 | 128 | |
E4-3PEP-8 | 36.00 | 27.00 | 32.00 | 164 | |
E4-3PEP-9 | 36.00 | 27.00 | 36.00 | 172 |
NEMA 4 Enclosures For Encapsulated Transformers (1 Phase)
Enclosure Size |
Width (in) |
Depth (in) |
Height (in) |
Weight (lbs) |
Downloads |
E4-1PEP-1 | 7.75 | 7.00 | 11.50 | 7 | |
E4-1PEP-2 | 8.50 | 7.50 | 12.50 | 8 | |
E4-1PEP-3 | 10.00 | 9.00 | 14.00 | 11 | |
E4-1PEP-4 | 12.50 | 14.50 | 15.00 | 35 | |
E4-1PEP-5 | 15.00 | 17.00 | 18.00 | 47 | |
E4-1PEP-6 | 18.00 | 16.00 | 25.00 | 68 | |
E4-1PEP-7 | 19.00 | 18.00 | 28.00 | 79 | |
E4-1PEP-8 | 25.00 | 22.00 | 33.00 | 114 | |
E4-1PEP-9 | 25.00 | 24.00 | 36.00 | 125 |
Distribution Transformer Enclosures
Standard NEMA 1 / 3R Ventilated Indoor Enclosures
Enclosure Size |
Width (in) |
Depth (in) |
Height (in) |
Weight (lbs) |
Downloads |
E1-0 | 9.50 | 7.00 | 8.00 | 7 | |
E1-1 | 12.00 | 9.00 | 9.30 | 11 | |
E1-2 | 11.00 | 11.00 | 14.00 | 21 | |
E1-3 | 15.50 | 11.00 | 14.00 | 24 | |
E3R-4 | 15.75 | 16.00 | 21.00 | 38 | |
E3R-5 | 20.50 | 16.00 | 25.00 | 48 | |
E3R-6 | 20.50 | 20.75 | 30.00 | 64 | |
E3R-7 | 24.50 | 21.75 | 36.00 | 86 | |
E3R-8 | 30.75 | 33.40 | 44.00 | 136 | |
E3R-8S | 27.00 | 29.00 | 47.00 | 107 | |
E3R-9 | 40.00 | 38.00 | 52.00 | 211 | |
E3R-9S | 32.00 | 32.00 | 52.00 | 158 | |
E3R-10 | 46.00 | 50.00 | 66.00 | 338 | |
E3R-11 | 60.00 | 55.00 | 70.70 | 400 | |
E3R-12 | 73.00 | 56.00 | 79.50 | 710 |
Standard NEMA 3R Ventilated Outdoor Enclosures (c/w weather kit)
Enclosure Size |
Width (in) |
Depth (in) |
Height (in) |
Weight (lbs) |
Downloads |
E3R-2-W | 11.00 | 16.10 | 14.00 | 23.5 | |
E3R-3-W | 15.50 | 16.10 | 14.00 | 27.5 | |
E3R-4-W | 15.75 | 21.10 | 21.00 | 42 | |
E3R-5-W | 20.50 | 21.60 | 25.00 | 54 | |
E3R-6-W | 20.50 | 26.40 | 30.00 | 69.5 | |
E3R-7-W | 24.50 | 29.40 | 36.00 | 93.5 | |
E3R-8-W | 30.75 | 37.50 | 44.00 | 145.5 | |
E3R-8S-W | 27.00 | 30.00 | 47.00 | 115 | |
E3R-9-W | 40.00 | 41.75 | 52.00 | 231 | |
E3R-9S-W | 32.00 | 35.00 | 52.00 | 166 | |
E3R-10-W | 46.00 | 50.00 | 66.00 | 353 | |
E3R-11-W | 60.00 | 55.00 | 70.70 | 436 | |
E3R-12-W | 73.00 | 56.00 | 79.50 | 750 |
Standard NEMA 12 Ventilated Enclosures
Enclosure Size |
Width (in) |
Depth (in) |
Height (in) |
Weight (lbs) |
Downloads |
E12-6 | 20.50 | 25.40 | 30.00 | 104 | |
E12-7 | 24.50 | 26.40 | 36.00 | 123 | |
E12-8 | 30.75 | 34.50 | 44.00 | 193 | |
E12-9 | 40.00 | 37.70 | 52.00 | 211 | |
E12-10 | 46.00 | 46.30 | 66.00 | 493 | |
E12-11 | 60.00 | 51.30 | 70.70 | 735 | |
E12-12 | 73.00 | 51.70 | 79.50 | 898 |
Standard NEMA 4 Sealed Enclosures
Enclosure Size |
Width (in) |
Depth (in) |
Height (in) |
Weight (lbs) |
Downloads |
E4-4 | 15.50 | 16.50 | 18.00 | 44 | |
E4-5 | 21.50 | 16.75 | 20.50 | 63 | |
E4-6 | 21.50 | 22.00 | 27.00 | 90 | |
E4-7 | 24.50 | 22.25 | 31.50 | 101 | |
E4-8 | 30.75 | 30.50 | 32.00 | 143 | |
E4-9 | 40.00 | 34.00 | 46.00 | 286 | |
E4-10 | 46.50 | 43.25 | 64.50 | 466 | |
E4-11 | 60.00 | 50.50 | 71.00 | 616 | |
E4-12 | 73.00 | 48.50 | 80.00 | 761 |
Motor Starting Autotransformer
Motor starting autotransformers are a special transformers used in the autotransformer starting of a industrial motors. Autotransformer starting of motors is used widely in starting large industrial motors due to its advantage of providing the highest starting torque with lowest starting line current compared to other reduced voltage starting methods. The reduced voltage taps of the motor starting autotransformer are used to reduce the starting current of the transformer. Contactors switch between the taps, incrementally, increasing the votatge applied to motor as it gets up to speed, while ensuring the starting current is limited. Once the motor reached rated speed, the autotransformer is removed from the circuit entirely, avoiding any unnecessary energization losses.
Read more: Motor Starting Autotransformer
Hazardous Location Transformer
Product Overview & Application
“Hazardous Locations and Harsh Industrial Environments” typically refers to areas which may contain dangerous and corrosive, explosive or combustible gases, liquids, or dust. Typical applications include mining, petrochemical, and pulp and paper industries. Rex Power Magnetics has been designing and producing a line of dry type transformers for Hazardous Locations and Harsh Industrial Environments. Rex’s product offering in this category includes three varieties, known as the HLA, HLB & HLC product lines, which are CSA and UL approved for CLASS I, DIVISION 2, GROUPS A, B, C, & D.
- Group A: Atmospheres containing acetylene.
- Group B: Atmospheres containing butadiene, ethylene oxide, hydrogen (or gases of vapors equivalent in hazard to hydrogen, such as manufactured gas) or propylene oxide.
- Group C: Atmospheres containing acetaldehyde, cyclopropane, diethyl ether, ethylene, hydrogen sulfide, or unsymmetrical dimethyl hydrazine (UDHM), or other gases or vapors of equivalent hazard.
- Group D: Atmospheres containing acetone, acrylonitrile, alcohol, ammonia, benzene, benzol, butane, ethylene, dichloride, gasoline, hexane, isoprene, lacquer solvent vapors, naphtha, natural gas, propane, propylene, styrene, vinyl acetate, vinyl chloride, xylenes, or other gases or vapors of equivalent hazard.
*NEW* A variant of Rex’s HLA & HLB transformers is available with IECEx approved CLASS 1 Zone 2 certification. Please contact our sales office for more information on IECEx approved transformers CLASS I, ZONE 2, GROUPS IIA, IIB, IIC
- Group II A: Atmospheres containing acetaldehyde, acetone, cyclopropane, alcohol, ammonia, benzene, benzol, butane, ethylene, dichloride, gasoline, hexane, isoprene, lacquer solvent vapors.
- Group II B: Atmospheres containing acrylonitrile, butadiene, diethyl ether, ethylene, ethylene oxide, hydrogen sulfide, propylene oxide, or unsymmetrical dimethyl hydrazine (UDHM), or other gases or vapors of equivalent hazard.
- Group II C: Atmospheres containing acetylene, carbon disulfide, hydrogen or other gases or vapors of equivalent hazard.
Product Specification
FEATURES | TPYE HLA | TYPE HLB | TYPE HLC |
Construction Features |
|
|
|
Insulation Class | 200C | 200C | 220C |
Temperature Rise | 80C or 115C | 80C or 115C | 80C, 115C or 150C |
Temperature Code | T3C or T3 | T3C or T3 | T3C, T3, or T2C |
Enclosure |
|
|
|
Certification | CSA & UL approved for Class 1, Division2 | CSA & UL approved for Class 1, Division2 | CSA & UL approved for Class 1, Division2 |
Application | Windings are encapsulated in epoxy, preventing airborne contaminants from reaching the coils, and thus preventing damage to the electrical insulation. | As with HLA, the windings are encapsulated. Additionally, the connection between the leads and the coils are encapsulated. Wiring to the rest of the system is done at the leads. | Conventional construction: non-encapsulated, vented design. Designed to conform to specified temperature code. |
Documentation
K-Factor Rated Transformer
Today's modern electronic, electric components and circuitry such as computers, copiers, printers, fax machines and display terminals utilize switching mode power supplies for their operation. These switching mode power supplies are non-linear in nature and unlike a linear load which uses current from the power source continuously over the sinusoidal cycle, a non-linear load draws current in pulses from the power source thereby creating harmonic distortion. These harmonics currents cause significant power system problems such as:
- Circuit breakers and fuses blowing far below current ratings
- Neutrals in transformers and panel boards are much hotter than their ratings
- Distributions Transformers are overheating even when operating well within their specified nameplate rating
Read more: K-Factor Rated Transformer