TYHD-4 cable earthed fault indicator is applied to cable system below 35KV, with function of zero-sequence earthed fault detection and fault signal remote transmission function. the panel indicator displays and remotely transmitted the detected fault signal from earthed fault indicator transmitted by optical fiber,when earth fault happened in cable. It can help line finder find the fault location quickly .shorten power-off time,improve the reliability of power supply. The picture of product is below:

working principle:

Using specially designed open zero-sequence CT as sensor of measuring zero-sequence current, micro-power consumption intelligent controlling chip is as core. When earth fault happen, earthed detector will automatically distinguish fault current characteristics to judge earth fault intelligently, then transmit the data to panel indicator to display by optical fiber, and the panel indicator will send wireless signal to DTU to realize the remote transmitting for fault signal.

Functions and characteristics:

1) Install and uninstall simply.adaptable to detect zero-sequence current in three-phase cable with outer diameter below 110mm.

2) Epoxy resin casting,adaptable to run outside in a long term

3 )detect earthed fault

3.1)Used for low resistance grounding system:zero-sequence current starting value adjusted range is 10-200A before delivery,default value is 30A;delay time range can be adjusted as 50mS~60S before delivery, default value is 200ms.when zero-sequence current is above current starting value and lasting time is above delay setting time then it can be judged as fault. The parameters can’t be changed at site, need to clarify when make order.

3.2)Used for low current earthed system: detect special signal and meet fault judgement condition then judged as earthed fault.

4)optical fiber communication

transmit fault signal from detector to panel indicator

5) Equipped with a Built-in a lithium battery, life is above 8 years

system structure diagram:

working power: 3.6V/2Ah lithium battery is equipped for supply；

static power consumption:3.6V power supply＜5uA

long endurance current:500A

short endurance current:2000A/2S

optical fiber communication distance:10m

optical fiber data rate:9600bps

weight:<1.1kg

There is type test report for it, test items as following: