ABB Relion 620 Series - Page 679

t s d
k
M
( )
.
( )
= +
−
0 18
1
2
(Equation 136)
t(s) Operate time in seconds
d
Constant delay setting in milliseconds
M Excitation value (U/f ratio or volts/hertz) in pu
k Time multiplier setting
Figure 353: Operating time curves for the overexcitation IDMT curve 4 ("OvExt IDMT
Crv4") for different values of the Time multiplier setting when the Constant delay is
800 milliseconds
The activation of the OPERATE output activates the BLK_RESTART output.
For the IDMT characteristic "OvExt IDMT Crv4", the deactivation of the OPERATE
output activates the cooling timer. The Timer is set to the value entered in the
Cooling time setting. The Restart Ena level setting determines the level when
BLK_RESTART should be released.
enable restart time
Ena restart level
Cooling time=
−






⋅
100
100
(Equation 137)
1MRS757644 H
Protection functions
620 series
Technical Manual
679