Sel SEL-787 - Page 142

4.56
SEL-787 Relay Instruction Manual Date Code 20150130
Protection and Logic Functions
Voltage-Based Protection
Figure 4.41 Volts/Hertz Inverse-Time Characteristic, 24IC = 1
t
p
24ITD
VPP PTR
freq
-----------------------------
FNOM
VNOM 10
3

---------------------------------

24IP
100
------------
---------------------------------------------------------------------






1–







1.0
-----------------------------------------------------------------------------------------------
seconds=
if V/Hz 1.5 24IP
t
p
2.0 24ITD seconds=
if V/Hz 1.5 24IP