How to make a secondary current tester 80A low price

[Guilhermebr]

I need to do some testing on a protection relay of up to 80A. Does anyone have a simple things diagram for me to assemble?

GS

 

[waross]

Wind some turns on a window CT. Use a ballast resistor and a Variac to power it.

Bill
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"Why not the best?"
Jimmy Carter

 

[ScottyUK]

Find a toroidal transformer of sufficient VA rating to handle your burden. Loop a few turns of heavy cable through the core, and leave the regular secondary open-circuit. Connect a Variac to the primary winding.

This basically what Bill has described, other than a toroidal transformer has a primary of known characteristics whereas a CT will require some guesswork and/or calculation to enable you to use it effectively.

 

[Guilhermebr]

Hello.

I thought in use a variac with welding machine transformer, because I need more VA. The secondary transformer will be short circuit. Will I have current precision, just moving variac?

GS

 

[DTR2011]

Some variac based relay test sets have provisions for inserting a series resistance in the primary. The result is more precision in setting the desired current.