Recent content by Manoj Sahu

Exactly. It's installed in a 66kV Gas Insulated Substation

It has 4 core marked as 1S1-1S2-1S3 400-300/1A 2S1-2S2 3S1-3S2 4S1-4S2

As you said metering core needs to be accurate all the time and protection core accuracy must be at least known or 10- 20 nominal current, is this the reason protection core is having larger saturation point. I have a CT in which there are 4 core. The first core is used for metering whereas the...

Yes. Exactly. Voltage on y -axis and Current on x -axis. You have marked at the right place. The result was as follows Knee point voltage -804V Current - 5.508 mA

While doing the knee point test, I injected voltage upto 1500 V in a current transformer having knee point voltage 750V @ 30mA. The test was performed using Omicron's CPC 100 and it also had option to demagnetize.

Thanks Jim I meant calculated/decided by the designer. If a current transformer is saturated, does it act like permanent magnet.

Thank you

I have to test a Current transformer. I read knee point is a point at which 10% increase in voltage leads to 50% increase in current. As there are different classes of current transformer (cores), how it is decided what/how much will be the knee point voltage of that core.

I don't exactly remember. Suppose, it is 13. How will we calculate?

I performed this test on Siemens 33kV GIS 8DB 10 panel. The test results were around 210micro ohm whereas the ideal values were 173micro ohm. I asked my Seniors , how come they calculated the ideal value of 173 micro ohm. They told me that it depends on number of contacts and can be easily...

I was wondering about contact resistance measurment test. Why do we take such test?

This is very helpful. Can you please suggest me few sources or references to read more about this topic?

I have this only @anorlunda

Thank you for replying. Practically, I have observed few things. When the circuit breaker is ON, the load break switch can be turned ON or OFF but the Earth switch cannot be turned ON. Similarly, when Earth switch and breaker is ON, load break switch cannot be turned ON