Protection vs. Metering 1

[tulum]

Hello,

Is it appropriate/advantageous to place an ammeter on the same ct as an instantaneous overcurrent relay and a motor protection relay ( all burdens in series)? i.e. metering and control on same ct?


Thanks in advance...

 

[CJFlatters]

Interesting stuff -

Jbartos - Thanks for the tip about the millivoltmeter / shunt / TVSS option. Which particular voltage limiting devices to you use to protect personnel (re your reply 11/4).

Thanks chaps.

_______________________________________
Regards -

Colin J Flatters
Consulting Engineer & Project Manager

 

[jbartos]

Suggestion to the previous posting: Visit

http://www.powersmiths.com/products/smart1.shtml

for:
The Powersmiths SMART1 package provides safe and easy external access to live transformer primary and secondary voltages and currents, operating temperature, and TVSS status (if installed) without opening the transformer enclosure.

 

[RRaghunath]

I have seen Japanese also including the ammeter in the secondary ckt of protection class CT.
I think it is no problem considering that present day meters can withstand 10times the rated current for 0.5second, typically.
The protection class CTs are mostly with accuracy limit factor 10 (say 5P10 to IEC).