Page 327 - Industrial Power Engineering and Applications Handbook

12/306 Industrial Power Engineering and Applications Handbook

1 Temperature monitor
in the windings.
@ PTC thermistors in the
end windings.
@ Temperature sensors in
the bearings.
@ Vibration probes
@ Pulse transmitters
@ Speed responsive
switches
Tachogenerator (TG)

Figure 12.39(a) General safety devices and their locations in a motor

n I u or rnerrno-couples
terminals for monitoring
and protection

Thermistor terminals
for alarm or triD
-I

I" windings
Thermistors and RTDs or
thermocouples are
embedded in all the three
phases of the stator

Figure 12.39(b) Wiring diagram

and final assembly of the motor by the motor manufacturer.
All these accessories are normally optional and must be
requisitioned to the motor manufacturer at the time of
the initial indent. These devices can be of the following
types.

12.8.1 Motor winding temperature detection Figure 12.40 Thermistor motor protection relay (Courtesy: L&T)
(by PTC thermistors and RTDs)
spots and provide an audio-visual alarm, annunciation
HT motors specifically, and large LT motors generally, and protection signals. For a stator winding, the preferred
are recommended to have six such detectors, two in each locations for a PTC thermistor and an RTD may be
phase to sense or monitor the temperature of likely hot considered as below: