product overview

Current transformers (CTs) are widely used in power systems for primary measurement and control. During normal operation, the secondary measurement of the transformer is in an approximately short-circuit state, and the output voltage is very low. When the secondary winding is open or abnormal currents flow through the primary winding (such as lightning current, resonant overcurrent, capacitor charging current, inductor starting current, etc.), overvoltage of thousands or even tens of thousands of volts will be generated on the secondary side. This not only poses a threat to the insulation of the secondary system, but also causes the transformer to overheat and burn out, and even endangers the safety of workers. The use of CTB series current transformer overvoltage protector can effectively prevent accidents caused by open circuit on the secondary side of the current transformer.

application

CTB protectors are mainly used for abnormal overvoltage protection on various CT secondary sides. The protector is connected to both ends of the secondary winding, and during normal operation, the leakage electrode is small, resulting in a high resistance state. When an abnormal overvoltage occurs, the protector quickly acts and short circuits, and the panel displays the faulty area with passive signal output. After the fault is eliminated and the circuit is restored to its original state, it is put back into normal operation. CTB protectors are applied to differential windings, measuring windings, busbar protection windings, backup windings, etc. on the secondary side of CT.

major function

During normal operation, the current flowing into the protector does not exceed 0.1mA. Does not affect the normal operation of CT.

When the voltage between CT1 and COM exceeds 150V, CTB will automatically provide short-circuit protection at both ends.

The contact capacity of the relay is greater than 5A. So when there is a malfunction, it can reliably short-circuit the CT secondary side.

The relay contacts have a holding function, and the protection can only be released by pressing the "reset" button.

If the fault is resolved during a power outage, press the reset button after powering on to continue normal operation.

The device provides a relay contact output, which automatically closes when any CT circuit is open. It can be connected to various sound and light alarms or provided to comprehensive protection devices for remote information transmission. The contact will not disconnect until the fault is resolved and there is no short circuit protection.

TECHNICAL INDEX

Normal leakage current IL20V: ≤ 1mA

◎ Conducting voltage UC: 150V ± 10%

◎ Conduction time TS: 50ms ≤ Ts ≤ 250ms

◎ Remote signaling relay contact capacity: AC 220V/5A

◎ Protection relay contact capacity: AC 220V/5A

◎ Protection current: ≥ 5A

◎ Working environment: Temperature: -20 ℃~70 ℃ Humidity:< 95％RH

◎ Reset method: manually press the "Reset" button; Automatic 'reset' when powered on

◎ Seismic performance: 10~50~10Hz 2g 3min

◎ Anti interference: 4.4KV/M

◎ Voltage resistance: 2.5KV AC, leakage current 0.5mA, 1min

◎ Reliability and safety: compliant with IEC834-1 requirements

◎ Dimensions: 1 winding 48 × 48 × 90 (mm) 2~12 windings 145 × 90 × 73 (mm)

◎ Installation method: rail type installation (35mm), bolt fixed installation