GE C70 Instruction Manual page 367

5 SETTINGS
To ensure element accuracy for high overcurrent conditions, the maximum value of I/(k x I
istically it is exceeding this value.
The reset time of the thermal overload protection element is also time delayed using following formula:
In the above equation,
• τ = thermal protection trip time constant
rst
• T is a minimum reset time setting
min
Figure 5–112: IEC 255-8 SAMPLE OPERATE AND RESET CURVES
The thermal overload protection element estimates accumulated thermal energy E using the following equations calculated
each power cycle. When current is greater than the pickup level, I
GE Multilin
 (
kI
B
τ × ---------------------------- -
t ln 
=
rst rst
2

I ( kI
–
E E
= +
n n 1
–
C70 Capacitor Bank Protection and Control System
) is limited to 8, even when real-
B
2
) 
 T
+
min
2

)
B
> k × I , element starts increasing the thermal energy:
n B
t Δ
-------------- -
t
op In ( )
5.7 CONTROL ELEMENTS
(EQ 5.23)
(EQ 5.24)
5-243
5