I. Overview of the Equipment

Current transformers (CTs) are widely used in power systems for primary measurement and control. During normal operation, the secondary side of the transformer is in an approximately short-circuited state, resulting in a low output voltage. If the secondary winding is open-circuited during operation, or if an abnormal current flows through the primary winding (such as lightning current, resonance overcurrent, capacitor charging current, inductor start-up current, etc.), overvoltages of thousands to tens of thousands of volts can be induced on the secondary side. This not only harms the insulation of the secondary system but also can cause the transformer to overheat and burn, even threatening the safety of the personnel. The KY-CTB series current transformer overvoltage protector can effectively prevent accidents caused by secondary overvoltage of the current transformer.

Part Two: Application

The BHG-CTB Overvoltage Protection Relay for Current Transformers is primarily used for abnormal overvoltage protection on various CT secondary sides. The protector is connected at both ends of the secondary winding, operating with minimal leakage current and in a high-resistance state under normal conditions. In the event of abnormal overvoltage, the protector acts quickly, short-circuiting itself, and the control panel displays the location of the fault along with a passive signal output. This product employs a high-stability microcontroller for control, enabling communication with the back-end monitoring computer network via the RS-485 bus, facilitating real-time remote environmental monitoring of the primary system. After the fault is cleared and the circuit is restored, it resumes normal operation.

BHG-CTB is applied to overvoltage protection for differential windings, overcurrent windings, measuring windings, busbar protection windings, and standby windings on the secondary side of CTs.