Medium Voltage Power Transformers
VPI/VPE Power Transformers
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. The VPE process builds a thick coat of epoxy over the windings which increases the windings resilience in humid and dirty environments.
Rex Vacuum Pressure Impregnated (VPI) dry type power transformers are primarily designed for stepping down high voltages from transmission and distribution systems to lower voltages which can be utilized in commercial, industrial, institutional or utility applications. They are ideally suited for both indoor and outdoor applications and require minimal maintenance to provide many years of reliable trouble free service. Unlike liquid filled transformers which are cooled with oil or a fire resistant liquid dielectric, dry type units utilize only environmentally safe, CSA and UL recognized high temperature insulation systems. Dry type designs provides a safe and reliable power source which does not require fire proof vaults, catch basins or the venting of toxic gasses. These important safety factors allow the installation of dry type transformers inside buildings close to the load, which improves overall system regulation and reduces costly secondary line losses.
Typically, dry type transformers are designed in one of the following three configurations:
1. General Purpose Power Transformer
General purpose power transformers are designed with primary and secondary bus stubs terminals suitable for side or bottom cable entry directly into the transformer enclosure. The terminals are mounted in a “stubs up” or “stubs down” configuration and electricians route the incoming and outgoing cables directly to these terminals. Optionally, the bus terminals can be routed to the either end of the enclosure to reduce the amount of internal cable routing required on site. For top cable entry applications, the terminals may be routed to an air terminal chamber (ATC).
2. Unit Substation Transformer
UnitSubstationUnit substation transformers are designed for close coupling with primary and/or secondary equipment. Transformer terminals are bussed to the either end of the transformer, and their exact location is coordinated with the equipment the transformer will be integrating with. The enclosure end walls feature openings which line up with the primary and/or secondary equipment, and flex connector can be utilized to connect the transformer with the other equipment. Unit substations are ideal for reducing the required space in an electrical room as the equipment can be installed right up against one another without the need for transition cells.
3. Pad Mounted Transformer
PadMountPad mounted transformers feature a compartmentalized design with front accessible and pad lockable primary and secondary air terminal chambers. These configurations are particularly well suited for outdoor areas with underground incoming and outgoing power service where the general public may be present. Transformer voltage taps are accessible from the rear via a removable panel or pad lockable door and tamperproof enclosure hardware is utilized to deter forced entry.
Rex Power Magnetics has over 30 years of experience designing and manufacturing medium voltage power transformers to meet various requirements and applications which include:
- Zig Zag Grounding Transformers
- Single Phase Neutral Grounding Transformers
- Triplex Configuration Transformers
- Transformers for Mining, Pulp and Paper Application
- Corrosion Resistant Transformers for Marine Applications
- Low Electromagnetic Field Emission Transformers For Hospital and Institutional Use
- Traction Power Rectifier Transformers for Transit Systems
- Motor Starting & Drive System Applications
- High Harmonic and Intermittent Load Applications
Our technical team is always ready to find a solution and design a custom transformer for the most challenging applications.
| Capacity | 100 to 5,000 kVA Single Phase and 300 to 15,000 kVA Three Phase | |
| Voltage Class | up to 46kV (250kV BIL) | |
| Cooling | Air Cooled (ANN) [Optional Forced Air Cooled (AFN/AF)] | |
| Frequency | 60Hz [50/60Hz Optional] | |
| Conductors | Copper (Cu) or Aluminum (Al) Windings | |
| Insulation System | 220°C (150°C Temperature Rise) [Optional 115°C & 80°C Rise Available] | |
| Impregnation | Epoxy Vaccum Pressure Impregnated (VPI) and Baked [Optional VPE] | |
| Efficiency | Meets North American Energy Efficiency Standards:
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| Primary Taps | Typically +/-2 x 2.5% taps | |
| Sound Level | Meets IEEE C57.12.01 | |
| Configuration | Terminal Bus Stubs Suitable For Cables [Optional Unit-Substation or Padmount Configuration] | |
| Enclosure Type | Type 1 Indoor [Type 2, 3R, 4, 4X & 12 Optional] | |
| Enclosure Finish | ANSI 61 Grey Powder Coat | |
| Testing | Std Production Tests (per IEEE C57.12.91)
|
Optional Type Tests
Other Optional Tests
|
| Warranty | 18 Months (See Warranty and Limitations) | |
| Quality System | ISO 9001:2015 Quality Management System | |
| Certifications |
|
|
| Reference Standards |
|
|
| Optional Features & Accessories |
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|
Drawings for 150°C or 115°C Rise, Stubs Up, Max. 600V/10kV BIL on L.V.
Drawings of 150°C or 115°C Rise, Stubs Up, Max. 600V/10kV BIL on L.V.
Product Catalogs
Power Transformer Catalog (English)
Power Transformer Catalog (French)
Instruction Sheets & Manuals
Maintenance, Operating & Installation Manual (English)
Maintenance, Operating & Installation Manual (French)
Other Resources
Photos
Videos
- Zig Zag Grounding Transformers
- Single Phase Neutral Grounding Transformers
- Triplex Configuration Transformers
- Transformers for Mining, Pulp and Paper Application
- Corrosion Resistant Transformers for Marine Applications
- Low Electromagnetic Field Emission Transformers For Hospital and Institutional Use
- Traction Power Rectifier Transformers for Transit Systems
- Motor Starting & Drive System Applications
- High Harmonic and Intermittent Load Applications
- U.S. – (DOE 2016) DOE 10 CFR Part 431
- Canada – (NRCan 2019) SOR/2018-201, Amd. 14 & ON Reg. 404/12
- Winding Resistance
- Turns Ratio
- Polarity and Phase Relation
- No-Load Loss and Excitation Current
- Load Loss & Impendance
- Applied Potential
- Induced Potential
- Basic Insulation Level (BIL)
- Temperature Rise (Heat Run)
- Sound Level
- Partial Discharge
- RIV
- Power Factor
- CSA Certified
- UL Listed
- CSA C22.2 No 47
- CSA C9
- IEEE C57.12.01
- IEEE C57.12.91
- Provision for Future Fans or Fan Packages (AFN) completely installed with or without Control Power
- Buss Co-ordination with primary and secondary switchgear (Unit-Substation configuration)
- Dial (Analog) or Digital Thermometers to monitor winding temperatures
- Neutral Ground Resistors (NGR) and Monitoring
- Anti-Condensation Strip Heaters
- Switching surge mitigating R.C. Snubbers (with or without ground current monitoring)
- Ground Fault Protection Relays (GFR)
- Anti-Vibration mounting to reduce transformer hum (sound level)
- Provision for Seismic mounting or complete Seismic Snubbers and Restraints
- Distribution, Intermediate or Station Class Surge Arrestors
- Provision for Buss Duct Entry
- Fully Insulated Buss
- Mimic Buss
- Kirk-Key Interlock
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. The VPE process builds a thick coat of epoxy over the windings which increases the windings resilience in humid and dirty environments.
Rex Vacuum Pressure Impregnated (VPI) dry type power transformers are primarily designed for stepping down high voltages from transmission and distribution systems to lower voltages which can be utilized in commercial, industrial, institutional or utility applications. They are ideally suited for both indoor and outdoor applications and require minimal maintenance to provide many years of reliable trouble free service. Unlike liquid filled transformers which are cooled with oil or a fire resistant liquid dielectric, dry type units utilize only environmentally safe, CSA and UL recognized high temperature insulation systems. Dry type designs provides a safe and reliable power source which does not require fire proof vaults, catch basins or the venting of toxic gasses. These important safety factors allow the installation of dry type transformers inside buildings close to the load, which improves overall system regulation and reduces costly secondary line losses.
Typically, dry type transformers are designed in one of the following three configurations:
1. General Purpose Power Transformer
General purpose power transformers are designed with primary and secondary bus stubs terminals suitable for side or bottom cable entry directly into the transformer enclosure. The terminals are mounted in a “stubs up” or “stubs down” configuration and electricians route the incoming and outgoing cables directly to these terminals. Optionally, the bus terminals can be routed to the either end of the enclosure to reduce the amount of internal cable routing required on site. For top cable entry applications, the terminals may be routed to an air terminal chamber (ATC).
2. Unit Substation Transformer
UnitSubstationUnit substation transformers are designed for close coupling with primary and/or secondary equipment. Transformer terminals are bussed to the either end of the transformer, and their exact location is coordinated with the equipment the transformer will be integrating with. The enclosure end walls feature openings which line up with the primary and/or secondary equipment, and flex connector can be utilized to connect the transformer with the other equipment. Unit substations are ideal for reducing the required space in an electrical room as the equipment can be installed right up against one another without the need for transition cells.
3. Pad Mounted Transformer
PadMountPad mounted transformers feature a compartmentalized design with front accessible and pad lockable primary and secondary air terminal chambers. These configurations are particularly well suited for outdoor areas with underground incoming and outgoing power service where the general public may be present. Transformer voltage taps are accessible from the rear via a removable panel or pad lockable door and tamperproof enclosure hardware is utilized to deter forced entry.
Rex Power Magnetics has over 30 years of experience designing and manufacturing medium voltage power transformers to meet various requirements and applications which include:
Our technical team is always ready to find a solution and design a custom transformer for the most challenging applications.
| Capacity | 100 to 5,000 kVA Single Phase and 300 to 15,000 kVA Three Phase | |
| Voltage Class | up to 46kV (250kV BIL) | |
| Cooling | Air Cooled (ANN) [Optional Forced Air Cooled (AFN/AF)] | |
| Frequency | 60Hz [50/60Hz Optional] | |
| Conductors | Copper (Cu) or Aluminum (Al) Windings | |
| Insulation System | 220°C (150°C Temperature Rise) [Optional 115°C & 80°C Rise Available] | |
| Impregnation | Epoxy Vaccum Pressure Impregnated (VPI) and Baked [Optional VPE] | |
| Efficiency | Meets North American Energy Efficiency Standards:
|
|
| Primary Taps | Typically +/-2 x 2.5% taps | |
| Sound Level | Meets IEEE C57.12.01 | |
| Configuration | Terminal Bus Stubs Suitable For Cables [Optional Unit-Substation or Padmount Configuration] | |
| Enclosure Type | Type 1 Indoor [Type 2, 3R, 4, 4X & 12 Optional] | |
| Enclosure Finish | ANSI 61 Grey Powder Coat | |
| Testing | Std Production Tests (per IEEE C57.12.91)
|
Optional Type Tests
Other Optional Tests |
| Warranty | 18 Months (See Warranty and Limitations) | |
| Quality System | ISO 9001:2015 Quality Management System | |
| Certifications |
|
|
| Reference Standards |
|
|
| Optional Features & Accessories |
|
|
Drawings for 150°C or 115°C Rise, Stubs Up, Max. 600V/10kV BIL on L.V.
Drawings of 150°C or 115°C Rise, Stubs Up, Max. 600V/10kV BIL on L.V.
Product Catalogs
Power Transformer Catalog (English)
Power Transformer Catalog (French)
Instruction Sheets & Manuals
Maintenance, Operating & Installation Manual (English)
Maintenance, Operating & Installation Manual (French)
Other Resources
Photos
