GE 239 Instruction Manual page 88

5 MONITORING
c) TEMPERATURE
STATOR (BEARING) RTD1 (2-3) TEMPERATURE (OPTION): When enabled by 6 7(03(5$
•
785(?57'?57' $33/,&$7,21 , the actual temperature measured by each RTD will be dis-
played. For RTDs installed in the stator, interpretation of the temperature is more meaningful if
the insulation class of the stator windings is known. This value indicates how close the stator is
operating to its maximum allowable temperature. Consult the motor manufacturer's data for sta-
tor insulation class and maximum operating temperature. Insulation life typically is reduced by
half for every 10°C rise in temperature. Bearing temperatures vary with ambient conditions,
greasing, wear and loading. A significant increase in bearing temperature may indicate a prob-
lem that needs investigation. Temperatures can be viewed in °C or °F by selecting the appropri-
ate setpoint in 6  6(783?35()(5(1&(6?7(03(5$785( ',63/$< ,1 .
• THERMISTOR: Thermistors typically installed in motors for temperature detection are nonlinear
devices. When enabled, the thermistor readout will indicate hot or cold depending on whether the
thermistor resistance exceeds its alarm/trip threshold setpoint. If the terminals are left uncon-
nected while the thermistor function is set to trip or alarm or the thermistor resistance increases
above 31.5 kΩ, THERMISTOR NOT CONNECTED alarm message will be displayed. Therefore, if
the thermistor is not being used, the function must be set to off.
5
5-8
Courtesy of NationalSwitchgear.com
239 Motor Protection Relay
5 MONITORING
GE Multilin