Current Transformer CT Secondary Overvoltage Protector Function and Wiring
When the CT is working normally, the secondary side is in an approximate short-circuit state and the output voltage is very low, but if the secondary winding is open during operation, or the primary winding flows abnormal current (such as lightning current, resonant over-current, capacitor charging current, inductance startup Current, primary load short-circuit current, etc., will generate thousands of volts or even tens of thousands of volts over the secondary side, which not only causes damage to the secondary system insulation, but also makes the current transformer CT excessively over-charged and even burned. Endanger the safety of staff.
Current Transformer CT Secondary Overvoltage Protector Function
Current transformer CT secondary overvoltage protector is mainly used for abnormal overvoltage protection of various secondary CT sides. The current transformer CT secondary overvoltage protector is fixed to the two ends of the CT secondary winding. When the normal operation, the leakage current is very small, showing a high-impedance state; when an abnormal overvoltage occurs, the protector instantaneous action limits the voltage and delay. Short circuit and signal. Some current transformer CT secondary overvoltage protectors can also be used in other places where overvoltage protection is required. The fault location is automatically displayed on the panel and there is a passive contact signal output (products with communication can be realized). The over-voltage generated by the secondary winding causes the protector to rapidly act to short-circuit the secondary side of the CT. Press the manual reset button after the fault is removed (the new product can automatically reset), and the circuit can be put back into normal operation after it is restored to its original state.
Current Transformer CT Secondary Overvoltage Protector Function Wiring Principle
Under normal circumstances, current transformers are connected to three phases A, B, and C. A few are connected to two phases, and each phase is connected to one phase. Most current transformer secondary windings are star-connected and a few are delta-connected.
The main function
1. During normal operation, the current flowing into the protector does not exceed 0.1Ma, which does not affect the normal operation of the CT.
2. When the voltage across A (or B, C), N exceeds 150V, CTB shorts A (or B, C, N).
3, the relay contact capacity is greater than 15A. Therefore, when the fault occurs, the secondary side of the CT can be reliably short-circuited.
4. The relay contact has a holding function. Press the "Reset" button to release the protection.
5. If the fault is removed in the power failure state, the device will automatically reset after power failure.
6, CT overvoltage protector provides a pair of normally open contacts and a pair of normally closed contacts. When the protective action, normally open and closed, normally closed.
