Single-Pole Voltage Transformers (Potential Transformers), or Three-Phase VT (PT) + GVT (GPT)
EPF-10CE, EPF-20SK, EPF-20SL, EPF-20SNE, EPF-20DZE, EPF-30DE
Single-pole voltage transformers in this indoor medium-voltage range are epoxy-resin-cast potential transformers designed for 12 kV, 24 kV, and 36 kV power systems. These instrument transformers operate with measuring and monitoring instruments for power system analysis and supervision or in conjunction with protective relays to support system safety and reliability. Selected models can be equipped with a primary-side fuse assembly, and certain models offering a rated thermal burden of 1000 VA or higher may also serve as a power source for circuit breaker operation, functioning as control power transformers (CPT), control transformers (CTR), or industrial control transformers in switchgear and machine tool applications.
MV Indoor Epoxy-Cast Potential Transformers
About the Product
Single-pole voltage transformers in this indoor medium-voltage range are epoxy-resin-cast units designed for 12 kV, 24 kV, and 36 kV power systems. Also referred to as potential transformers (PTs), these instrument transformers are molded in Araldite® epoxy resin and are self-extinguishing, providing reliable insulation performance and moisture resistance in switchgear applications. They operate with measuring and monitoring instruments for power system analysis and supervision or in conjunction with protective relays to support system safety and operational reliability.
For models EPF-20SL and EPF-20SNE, optional primary-side accessories include an elbow-type connector and a tubular epoxy housing with a built-in primary fuse. This configuration enhances operational safety, simplifies maintenance, and supports more compact switchgear panel design.
Certain models offer a rated thermal burden of 1000 VA or higher, enabling them to function not only as voltage transformers but also as a power source for circuit breaker operation in medium-voltage switchgear systems.
Product Features and Selection Tables
- Indoor usage; cast in Araldite® epoxy resin for superior insulation
- Standard: IEC or IEEE
- Frequency: 50 or 60 Hz
- Models EPF-20SL, EPF-20SNE, and EPF-20DZE are available with single-voltage or dual-voltage primary ratings.
- EPF-20SL and EPF-30DE only: (Option) Elbow-type connector and tubular epoxy housing with a built-in primary fuse
- GVT (GPT) Functionality: Connect three voltage transformers (potential transformers) from this series through a Y-Y-open △ connection for the combined functionality of a three-phase VT (PT) and a grounding voltage transformer (grounding potential transformer) (i.e. 3Φ VT + GVT, or 3Φ PT + GPT).
a M = Voltage ratio of the measuring winding.
b R = Residual voltage ratio of the residual voltage winding, as defined in IEC 61869-3:2011, Clause 3.1.308, intended for broken-delta (open-delta) connection of a set of three single-phase voltage transformers.
c Applicable only to configurations with a primary voltage of 22/√3 kV.
d Values according to Standard Values of Rated Voltage Factors by IEC 61869-3: 2011.
Available Models
EPF-10CE, EPF-20SK, EPF-20SL, EPF-20SNE, EPF-20DZE, EPF-30DE
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CIC Company Profile
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【Product Brochure】Single-Pole Voltage Transformers, or Three-Phase VT + GVT
Easy-to-print document, containing product description, features, and a selection table.
【Product Dimensions】Single-Pole Voltage Transformers, or Three-Phase VT + GVT
Download PDF for basic drawing(s) and dimensions of this product. For more detailed information, please contact CIC.
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CT & PT Selection Guide: How to Choose a Current Transformer or Potential Transformer
How to select, based on application and power system attributes, the primary and secondary currents, burden, accuracy, rated frequency, type (indoor vs. outdoor), insulation material, etc.
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This voltage transformer, cast with self-extinguishing epoxy resin, is a medium-voltage, indoor-type, single-phase potential transformer for a 12kV or 24kV power system for measuring and monitoring voltage signals. With a continuous output capacity of 4000 VA (max.), it can also serve in a small substation or a switchgear panel as a power source for circuit breaker operation and lighting equipment*.* Power source for circuit breaker operation and lighting equipment: In this application, the voltage transformer can also be referred to as a "control power transformer" (CPT), "control transformer" (CTR), "industrial control transformer," or a "machine tool transformer."
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This ground voltage transformer (GVT), or ground potential transformer (GPT), is a three-phase medium-voltage (MV) potential transformer for indoor applications. With a fuse for each phase, this PT (VT) features epoxy-insulated coils and a five-legged (five-limbed) laminated core. This voltage transformer is used with measuring or monitoring instruments, or for ground-fault protection.
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