Zs on 2391

jonnyspeed · Apr 27, 2011

Hi, when doing periodic on 2391 do I calculate zs for motor circuit and MIMS radial?( if not then how? )

With the ring circuit I can test zs with socket tester and lights on db from ceiling rose? Is this correct as there are a just a few things I'm not sure of?

jonny

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Brian 157 · Apr 27, 2011

You'll be expected to measure Zs at the sockets but calculating is acceptable for other circuits. It's probably safer to calculate the motor circuit where you should have three R1+R2 values. Add Ze to the values & record the highest as Zs for the motor circuit.

jonnyspeed · Apr 27, 2011

One more thing. When re-energising after continuity and IR tests are completed on 3phase board and db,.. to find the PFC of the db will I need to safely isolate it first/before with lock+key or will the cover be already left off with main switch off and PFC performed along with zdb(ze) test? Sorry about this, this is my last question on this I promise ;0)

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Brian 157 · Apr 27, 2011

The point of isolation is usually seperate to the TP DB, if not leave the DB main switch locked off & test on the incoming side of the main switch where the incoming tails will be live.

jonnyspeed · Apr 27, 2011

Thankyou. I think I just needed confirmation that I would be working safely as it's a fail if not. Especially on safe isloation!

So when I re-energise the TP DB I will leave the cover off the other Db and lock off. Then test ze, PFC. Replace the cover then re-energise to do zs tests, rcd test and functional?

Just a thought.. I Should test phase rotation with TP DB cover off before re-energising right?

Actually, can I just replace the covers after re-energising?

I think I've confused myself ;0(

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