GE M60 - Page 410

5-202 M60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
GROUPED ELEMENTS CHAPTER 5: SETTINGS
5
Motor cooling is calculated as follows.
Eq. 5-14
Eq. 5-15
where
TCU = thermal capacity used
TCU
start
= TCU value caused by overload condition
TCU
end
= TCU value dictated by the hot/cold curve ratio when the motor is running. This value is 0 when the motor is
stopped)
t = time in minutes
 = cool time constant (running or stopped per current motor status and corresponding COOL TIME CONSTANT RUNNING and
COOL TIME CONSTANT STOPPED settings)
I
eq
= equivalent motor heating current
overload_pickup = overload pickup setpoint as a multiple of FLA
hot / cold = hot/cold curve ratio