ABB 615 series Technical Manual page 655

1MAC059074-MB A
615 series ANSI
Technical Manual
GUID-BD1205DC-1794-4F64-A950-6199C54DB7B1 V1 EN
Figure 322: Trip time curves for the overexcitation IDMT curve ("OvExt IDMT Crv1")
for parameters a = 2.5, b = 115.0 and c = 4.886
Overexcitation IDMT curve 4
The base equation for the IDMT curve "OvExt IDMT Crv4" is:
0 18 . k
t s ( ) d
= +
2
( M 1 )
−
GUID-361FE32F-D157-402D-BC70-D568AB809339 V1 EN
t(s) Trip time in seconds
Constant delay setting in milliseconds
d
M Excitation value (V/f ratio or volts/hertz) in pu
Time multiplier setting
k
Section 4
Protection functions
(Equation 123)
649