ASEA RIS & P&B Gold Protection Relays Time/Overcurrent Characteristic 2

[GVP]

Hello,

Can anybody direct me to ASEA RIS & P&B Gold Protection Relays Time/Overcurrent Characteristic Curve formulae.

Regards
GVP

 

[secv72]

Hi GVP,
regarding the RI characteristic, I quote the following from the manual for the ABB SPAJ140 combined overcurrent and earth-fault relay:

The RI-type characteristic is a special characteristic used mainly for time grading with existing mechanical relays. The characteristic is based on the following mathematical expression:

t = k / (0.339 - 0.236 x I> /I) where

t = operating time in seconds
k = time multiplier
I = phase current
I> = set starting current

P+B Golds are now called P+B Engineering and you could try emailing them, requesting information at mail@pbeng.co.uk or check their website at

http://www.pbeng.co.uk/

Hope that helps
SECV72