A
In a 11KV switchgear incomer the earth fault protection has been provided by using the sumamtion of three out puts of the mounted current transformers in three phases.
Some times it is observed that during starting of a largest motor feeder in the switchgear the protection mal faucntions causing outage of the switchgear.( Earth fault relay opeartion may be due to saturation of Current transformers resulting unablance current outputs in CT secondaries).
The current setting is 8% & cannot be increased further as the 11KV system is resistance earthed.
The time setting also cannot be incresed for the incomer from fault level point of view.
Now my question is whether is there any method avilable to make the above protection reliable.
Some times it is observed that during starting of a largest motor feeder in the switchgear the protection mal faucntions causing outage of the switchgear.( Earth fault relay opeartion may be due to saturation of Current transformers resulting unablance current outputs in CT secondaries).
The current setting is 8% & cannot be increased further as the 11KV system is resistance earthed.
The time setting also cannot be incresed for the incomer from fault level point of view.
Now my question is whether is there any method avilable to make the above protection reliable.