Meter Swap over - CT Question

[davesparks]

Help me out here. Is a ct clamp not just a load of thin wire with both ends connected to something that measures the induced current?
I get they could hold a capacitive charge but how can they be damaged bu failing to short them?

When they are installed around a conductor that conductor forms the primary winding of a transformer. So you have a transformer with a single winding primary and many many winnings secondary, the result being that if you disconnect the secondary whilst the primary is live the open circuit voltage of the secondary will be many times that of the primary.

Disconnecting without shorting the secondary leaves you with a few thousand volts between the terminals which is what causes the danger and potential damage.

 

[Marvo]

I would suggest you never open circuit the secondary circuit of a current transformer. If you do the voltage across the secondary coil can rise extremely high if there a load on the circuit it's clamped around. Sometimes CT's have built-in voltage clamping protection against this but don't ever assume that's the case. The high voltage that developes can damage the CT and it can also damage the person that's in the vicinity.

 

[davesparks]

Glad to see this is such a friendly forum and not just a place for people to belittle and shoe off. Jesus christ, think I'll go else where to confirm our plan. 40 years in the industry and still have to deal with know it alls

He was replying to westwards poor advice above, not your original question.

Nobody is trying to belittle you or show off.

The issue with your plan at the moment is that you need to have the short in place before disconnecting the existing meter.
The problem is that the moment you disconnect the CT secondary it will rise up to many thousands of volts.

 

[westward10]

Yes I was wrong didn't think of how high it could rise.

 

[UNG]

Glad to see this is such a friendly forum and not just a place for people to belittle and shoe off. Jesus christ, think I'll go else where to confirm our plan. 40 years in the industry and still have to deal with know it alls

What point are you trying to make
How to deal with CT's was something that I was taught in my first year at college back in the 70's my comment was not to belittle but to stress the dangers of handling CT's when they are live of which @davesparks has pointed out the pitfalls

You might find that the know it alls as you call them will be here tomorrow when the others that blindly do a job don't due to the unknown issues that bite them

With 40 years in the industry you will still find there are people out there that know more than you rather than being offended my advice would be learn from it

 

[Mikegh]

It sounds like the company involved in the works doesn't have the necessary expertise to undertake the task

A company that specialises in this work would have the knowledge