INDUSTRIES > POWER EQuIPMENT > Voltage Transformers > 12–24 kV Voltage Transformers
Indoor & Outdoor Voltage Transformers for Metering and Distribution
Keep Voltage in Check
Our 12–24 kV VT series covers a versatile range of indoor and outdoor applications, including metering, distribution, and specialized functions. The lineup includes:
Single-pole VTs combinable into three-phase VT and ground potential transformer sets
VTs for SF6-insulated MOF panels
Dual-function models serving as both voltage transformers and control power transformers, with an additional power source for circuit breaker operation
Metal conductive coating variants for electromagnetic shielding
Outdoor revenue metering VTs with UV-resistant cycloaliphatic epoxy resin, widely used by power utilities internationally
Units can be manufactured to IEC, IEEE, and other international standards, with customization, outdoor variants, and ODM/OEM services available on request.
All units are type-tested and routine-tested through a TAF-accredited (ILAC member) laboratory. We offer a wide range of specifications alongside customization and ODM/OEM services, making these CTs a proven choice for utilities, factories, and major infrastructure projects worldwide.
Single-Pole Voltage 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 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.
- Standard: IEC or IEEE
- Application: Indoors
- Construction: Single-pole; cast in Araldite® epoxy resin; self-extinguishing
- System Voltage: 12 kV, 24 kV, and 36 kV
- 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).
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.
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.
12 kV & 24 kV Epoxy-Cast Voltage Transformers for Indoor Use
EPF-3SF1, EPF-6SF2
EPF-3SF1 and EPF-6SF2 are primarily mounted on switchgear (3.3 kV and 6.6 kV, respectively) as an auxiliary power source for circuit breaker operation. Compact and of a flatter shape than other models, these voltage transformers are mounted on top of the power switch as an operation power source and are compatible with short-interval large output. With Araldite® epoxy resin as insulation, these voltage transformers also feature a Class-F heat-resistant insulation material for the coils. Two fuses on the primary side offer protection against overload and short circuit currents. EPF-3SF1 and EPF-6SF2 voltage transformers are characterized by a high-quality exterior, excellent moisture resistance, and superior electrical performance.
- Standard: IEC or IEEE*
- Application: Indoors
- Construction: Insulated with Araldite® epoxy resin
- System Voltage: 12 or 24 kV
- Frequency: 50 or 60 Hz
* For 22 kV / 110 V configuration only.
Conductive Shield Voltage Transformer for 24 kV 4-Way Switchgear
EPF-20FB
Specifically designed for 24 kV 4-way switchgear, this medium-voltage single-pole voltage transformer, or potential transformer, features a high-voltage elbow-type connector on the primary side and a built-in high-voltage fuse for protection. Since the exterior of the voltage transformer is coated with a metal conductive mixture for shielding, the necessary distance between the VT (PT) and the panels (or other equipment) is reduced.
Waterproof treatment can be requested for the secondary of the VT. This optional waterproof treatment will allow the VT to continue functioning even if immersed in water below the level of its primary-fuse housing (such as in the case of water accumulation on the street).
Insulated with Araldite® epoxy, this MV voltage transformer (potential transformer) is characterized by excellent water resistance, superior electrical performance, and great reliability, while being lightweight and compact.
Voltage Transformer for SF6 Gas-Insulated MOF Panel
EPF-20SH
Intended for power companies, the EPF-20SH single-phase voltage transformer, or potential transformer, is designed to be mounted inside the SF6 gas-insulated MOF (Metering Outfit) panel of a 25.5 kV (max.) power system. With an added tap in the secondary winding, this VT (PT) can offer two voltage ratios (120/60 : 1) and allows easy switching between the two, while maintaining the accuracy and burden rating of 0.3Y at each voltage ratio. Insulated with Araldite® epoxy resin, this indoor voltage transformer offers excellent electrical performance and high reliability.
12 kV & 24 kV Epoxy-Cast Voltage Transformer, as Power Source for Circuit Breaker Operation and Lighting
EPF-20DZ
Single-phase indoor-use voltage transformer (potential transformer) EPF-20DZ, intended for a 12 or 24 kV power system, is designed for the measuring and monitoring of the voltage signal.
Due to its continuous output capacity of 4000VA (max.), this voltage transformer can be used in a small substation or a switchgear panel as a power source for circuit breaker operation and lighting equipment. This setup helps to conserve space and reduce cost.
In addition, the EPF-20DZ voltage transformer can be connected to one or two smaller-capacity voltage transformers to form a three-phase voltage transformer (3ϕ VT). This can be done via a V-V or Y-Y connection.
Cast in self-extinguishing Araldite® epoxy resin, the EPF-20DZ voltage transformer is characterized by superior insulation and excellent safety.
This voltage transformer, in applications where it is used as a power source for circuit breaker operations and lighting equipment, can be referred to as a "control power transformer" (CPT), "control transformer" (CTR), "industrial control transformer", or a "machine tool transformer."
- Standard: IEC or IEEE*
- Application: Indoors; Power source for circuit breaker operation and lighting
- Construction: Self-extinguishing; Insulated with Araldite® epoxy resin
- Connection: V-V or Y-Y (optional, for forming 3-phase VT/PT)
- System Voltage: 12 or 24 kV
- Frequency: 50 or 60 Hz
** This specification includes a secondary tap, providing two secondary voltages (220 V and 110 V), serving as a dual-voltage potential transformer.
Outdoor-Type Voltage Transformers for Revenue Metering
VPF Series
Outdoor voltage transformers in the VPF Series are medium-voltage potential transformers designed to be part of a MOF (Metering Outfit) for revenue metering. Insulated with Araldite® UV-resistant cycloaliphatic epoxy resin, these 15.5–36.5 kV outdoor instrument transformers can withstand long-term exposure to solar ultraviolet radiation, salt fog, high temperature, high humidity, as well as other harsh environmental conditions.
- Standard: IEC or IEEE*
- Application: Outdoors; MOF (Metering Outfit) for revenue metering
- Construction:Insulated with UV-resistant cycloaliphatic epoxy resin
- Maximum System Voltage: 15.5 ~ 36.5 kV
- Frequency: 50 or 60 Hz
Precision Power Starts Here
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