Coordination between hi-set unit and IDMT-relay
Coordination between hi-set unit and IDMT-relay
(OP)
What is the time interval between a high-set (instantaneous) unit and IDMT-relay? I know time between relay-relay is 0.3 - 0.4 seconds, is it the same between high-set and relay or not?
Thanks
Thanks






RE: Coordination between hi-set unit and IDMT-relay
In general terms, the main point to remember is that you should try to avoid two devices tripping for the same fault by their Inst trips. This is done by limiting Main device Inst settings to the maximum fault value seen at the bus upon which they are located, or by not having Inst trips on the Main device at all.
RE: Coordination between hi-set unit and IDMT-relay
But you need to chick three point in the courve:
First:At low fault current the time diff bet the two relay >0.3sec
Second: At operation of Ins time >0.3 sec
Third: At max fult- extend the courve and chick the 0.3 sec.
This will be clear if you deal with curves.
RE: Coordination between hi-set unit and IDMT-relay
Electronic relays - 0.3 seconds
Electromecanical relays - 0.4 seconds
RCC
RE: Coordination between hi-set unit and IDMT-relay
RE: Coordination between hi-set unit and IDMT-relay
http://www.pbeng.co.uk/products/transformer/files/mspi.pdf
for:
7.5.4 Low set stage time multiplier/time delay
This is normally selected to give sufficient time delay between upstream and downstream operating
times to allow for breaker clearance and measurement errors etc. This is usually taken as 0.3 - 0.4
seconds
http://www.ee.polyu.edu.hk/staff/eekkli/BEngOpt/Lect/Ch3_OC2003.pdf
for: differences between time and time/current discriminations
etc. for more info
RE: Coordination between hi-set unit and IDMT-relay
see also:
http://www.usace.army.mil/inet/usace-docs/armytm/tm5-81-14/chap4.pdf
http://www.usbr.gov/power/data/fist/fist3~9/3~9_8.htm