Current Transformer(CT)
24 April, 2026
Delivering unparalleled precision for energy metering and robust reliability for relay protection. Engineered with anti-ferroresonance technology to secure medium and high voltage networks.
A Voltage Transformer (VT), also known as a Potential Transformer (PT), is an instrument transformer connected in parallel to the power system. It is designed to step down dangerously high system voltages (e.g., 12kV, 36kV) to standardized, safe, and measurable low voltages (typically 110V, 100V, or 110/√3V) for metering devices and protective relays.
Never short-circuit the secondary winding of an energized VT. Because a VT acts essentially as a step-down power transformer with very low internal impedance, shorting the secondary terminals will instantly draw a massive, uncontrolled fault current. This will rapidly overheat the thin primary windings, leading to severe thermal damage, insulation failure, and potential explosion.
SWITCHGEAR PANELS
Fully encapsulated in cycloaliphatic epoxy resin. Designed for air-insulated switchgear (AIS) and GIS. Highly flame-retardant and features excellent dielectric strength in compact enclosures.
ENHANCED SAFETY
Equipped with built-in high-voltage primary fuses. This integrated design saves cabinet space and ensures immediate disconnection from the busbar in the event of an internal VT failure.
OPEN AIR NETWORKS
Manufactured with UV-resistant silicone rubber or porcelain housings. Engineered with high creepage distances to withstand severe weather, icing, and heavy industrial pollution.
Many of our VTs are equipped with a secondary "residual" winding. When three such VTs are connected in an open-delta configuration, they actively monitor for zero-sequence voltage, instantly detecting dangerous single-phase-to-ground faults in the network.
In ungrounded networks, standard VTs can resonate with cable capacitance, causing severe overvoltages that destroy the transformer. Our engineered magnetic cores utilize specific silicon steel grades to heavily dampen ferroresonance, ensuring stable operation during grid disturbances.
| Parameter | Unit | 12kV Indoor VT | 24kV Indoor VT | 36kV / 40.5kV VT |
|---|---|---|---|---|
| Highest System Voltage (Um) | kV | 12 | 24 | 40.5 |
| Rated Primary Voltage | kV | 10 / √3 or 10 | 20 / √3 or 20 | 35 / √3 or 35 |
| Rated Secondary Voltage | V | 110 / √3, 100 / √3, 110, 100 | ||
| Residual Winding Voltage | V | 110 / 3, 100 / 3, 110, 100 | ||
| Metering Accuracy Class | - | 0.2 / 0.5 | ||
| Protection Accuracy Class | - | 3P / 6P | ||
| Rated Output Burden | VA | 15VA / 30VA / 50VA / 100VA | ||
| Thermal Limiting Output | VA | 250VA / 400VA / 500VA (Depending on model) | ||
Class 0.2 is a highly precise metering class, guaranteeing a voltage error of no more than 0.2% under normal operating conditions. It is used for revenue billing and accurate power meters. Class 3P is a protection class, guaranteeing an error limit of 3% but designed to maintain its accuracy across a much wider voltage range (e.g., during severe overvoltage faults) to ensure relays function correctly.
A Single-Pole VT (e.g., JDZX) has one primary terminal connected to the phase line, with the other end grounded. It is used to measure phase-to-ground voltage and can detect ground faults. A Double-Pole VT (e.g., JDZ) has two fully insulated primary terminals connected between two phases (phase-to-phase) and is typically used purely for metering and synchronization.
While the "Rated Output Burden" (e.g., 30VA) defines the maximum load the VT can drive while still maintaining its guaranteed accuracy class, the Thermal Limiting Output (e.g., 500VA) is the absolute maximum apparent power the VT can safely supply without exceeding safe temperature limits, disregarding accuracy.
Submit your requirements on a business day, and our engineers will provide an initial OEM proposal within 24 hours.
