57 - PVD3627-August 2011
3.6. Thermal Protection
Protection against thermal overloading of the motor is provided by one PTC
thermistors and one KTY temperature sensor (and one more in case of KTY failure)
built into the stator winding as standard. All thermal protection wires section is
AWG26.
3.6.1.
The thermal probes (PTC thermistors) fitted in the servomotor winding trip the
electronic system at 150°
±
5° C. When the rated tripping temperature is reached, the
PTC thermistor resistance changes very quickly. This resistance can be monitored by
the drive to protect the motor.
Alarm tripping with PTC thermistors :
The graph and tab below
shows the PTC resistance
as a function of temperature
(TN is nominal temperature)
Temperature
Resistance
value
-20°C up to TN-20°C R
≤250Ω
TNF-5°C
R
≤550Ω
TNF+5°C
R
≥1330Ω
TNF+15°C
R
≥4000Ω
4000Ω
Resistance (Ω)
1330Ω
550Ω
250Ω
T
N
-
20°
C
T
N
-
5
°C
T
N
+5
°C
T
N
+
15°
C
Temperature (°C)
-20°
C
Yellow Yellow
White
White
Brown
+
+
-
-