269 Plus Motor Protection System

The 269 Plus has a true exponential

cooldown characteristic which mimics

actual motor cooling rates. This allows

motors to be load cycled more frequently

since the initial rate of cooling is very

steep. Two setpoints are required to use

the exponential cooldown, the full load

current (FLC) reduction and the running

cool time.

The FLC reduction is the amount of thermal

capacity used when the motor is running

at a constant 100% FLC condition. This

represents the constant percentage

difference between the cold damage curve

and the hot damage curve. The running

cool time is the time for the thermal

memory to discharge from 100% to 0%

with the motor running in a non-overload

condition. If the motor comes from an

overloaded condition to a light load

condition, then the cooling rate is much

faster initially and the thermal capacity

used would be reduced accordingly.