Connecting
6.2 Electrical connection
1FE1 synchronous built-in motors
114
Hardware Installation Manual, 12/2016, 610.43000.40b
6.2.12
Temperature evaluation using the PTC thermistor triplet (full motor protection,
option)
For special applications (e.g. when a load is applied with the motor stationary or for
extremely low speeds), the temperature of all of the three motor phases must be additionally
monitored using a PTC thermistor triplet.
Note
If water-cooled synchronous built-in motors are operated for longer than one minute in
standstill with the standstill torque, a phase can be thermally loaded overproportionately.
•
Reduce the permanent standstill torque to 20%.
•
Protect the winding thermally with a thermistor triplet (PTC) with an external trip unit or
with an I
2
t monitoring of the drive system.
The PTC thermistor triplet must be evaluated using an external tripping/evaluation unit (this
is not included in the scope of delivery). This means that the sensor cable is monitored for
wire breakage and short-circuit by this unit.
The motor must be de-energized within 1 second when the response temperature is
exceeded.
Table 6- 2
Technical data for the PTC thermistor triplet
Designation
Technical data
Type (acc. to DIN 44082–M180)
PTC thermistor triplet
Thermistor resistance (20° C)
≤ 750 Ω
Resistance when hot (180° C)
≥ 1710 Ω
Connection
Via an external trip unit
Cable cross-section/outer diameter
0.14 mm
2
/0.9 mm
Response temperature
180° C
Note: PTC thermistors do not have a linear characteristic curve and are, therefore, not suitable for
determining the instantaneous temperature.
