COORDINATION OF
RELAY
If any fault occurs in motor, the neares relay has to trip ‘D’ breaker itself, so that it won’t affect the other system. Similarly if any fault occurs after ‘A’ breaker, the nearest is A breaker’s relay. So ‘A’ should trip and other system not affected.
Normally the operating and tripping of breaker time will be
around 350 msec.
If after ‘A’ breaker fault occurs ‘A’ will trip at 350msec
if it fails ‘B’ will trip at 700msec, I ‘B’ also fails ‘C’ will trip 1 sec.
This is called the co-ordination of Relays.
UNDER VOLTAGE RELAY:
This relay operates when under voltage occurs in a connected system, normally this relay setting be 80% of the applied voltage. This relay is used to trip the equipments connected, during under voltage condition. These relay having two types, instantaneous and IDMT (Inverse Definite Minimum Time)
IDMT relay are all dis type and the setting can be done
through plug setting arrangement.
AC – Alternating current where the voltage is alternating
from peak voltage (on both +ve –ve side) to ZERO voltage periodically.
DC – Direct current where the voltage in constant.
Your Blog shares a valuable information about Relay coordination. It is very helpfull to detect the problems in faults occur. The timing of device operation is verified using time current characteristics or TCCs, the device response curves plotted on log-log graph paper. The devices have inverse time current characteristics ITCCs. They operate quickly for large magnitude over currents, and more slowly for lower-magnitude over currents. Operating time is plotted on the vertical axis and Operating time is plotted on the vertical axis, and current magnitude is plotted on the horizontal scale. we are one of the top most Electrical hazard safety assessment consultants in the world.we provide services like Arc Flash Analysis, Short Circuit Analysis, Harmonic analysis, Relay coordination, etc, ....If you have any queries, Click on Relay Coordination <\a>
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