●product overview
Current transformers (CTs) are widely used in power systems for primary measurement and control. During normal operation, the secondary side of the current transformer is in an approximately short-circuit state, and the output voltage is very low. If the secondary winding is open during operation, or if an abnormal current flows through the primary winding (such as lightning current, resonant overcurrent, capacitor charging current, inductor starting current, etc.), it will generate thousands or even tens of thousands of volts of overvoltage 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 protectors can effectively prevent accidents caused by secondary open circuits of current transformers.

●Main purpose
The CTB series current transformer overvoltage protector is mainly used for abnormal overvoltage protection on the secondary side of various CTs. 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 (exceeding 150V) occurs, the protector quickly acts and short circuits, and the faulty part is displayed on the panel with passive signal output. After troubleshooting and restoring the circuit to its original state, it resumed normal operation. Therefore, the CTB series current transformer overvoltage protector is applied to the differential winding, overcurrent winding, measurement winding, busbar protection winding, backup winding, etc. on the CT secondary side.
The CTB series current transformer secondary overvoltage protector (open circuit protector) professionally produced by the company based on years of industry experience and advanced technical strength according to the actual application and needs of the power system can have the characteristics of action holding contact output, automatic light display, automatic locking differential protection, manual or automatic reset, and multiple flexible combinations. It has different installation methods such as board fixed, rail fixed, embedded, etc., which can meet the CT protection needs of various types and occasions. The product has advanced design, long working life, and reliable operation of more than 100000 times; Fast action speed and strong overload capacity (exceeding 5 times the rated value in a short period of time); The static current is small, and the current flowing into the protector during normal operation is less than 0.1mA, which does not affect the normal operation of the CT.

●TECHNICAL INDEX

Normal leakage current IL20V: ≤ 1mA

Normal operating current: ≤ 0.1mA

◎ Conducting voltage UC: 150V ± 10% (default, can be set according to customer requirements)

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

◎ Remote signaling relay contact capacity: AC 220V/5A; DC 110V/5A

◎ Protective relay contact capacity: AC 220V/15A

◎ CT specifications used: secondary peak value greater than 150V

◎ Protection current: ≥ 5A

◎ Power consumption: ≤ 5VA

◎ Working environment: Temperature: -20 ℃~70 ℃ Humidity: ≤ 85% RH Altitude: ≤ 2500M

◎ 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

◎ Auxiliary power supply: AC (DC) 220V, allowing 85V-270V

◎ Reliability and safety: compliant with IEC834-1 requirements

◎ Dimensions: 1 winding 48 × 48 × 90 (mm) 4~9 windings 145 × 90 × 73 (mm)

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