Motor Components; Thermal Motor Protection - Siemens SINAMICS S120 Configuration Manual

Motor components

5.1

Thermal motor protection

A temperature-dependent resistor is integrated in the stator winding to monitor the motor
temperature.
Table 5- 1
Designation
Type
Resistance when cold (20 °C)
Resistance when warm (100 °C)
Response temperature
Connection
NOTICE
The polarity must be observed.
The resistance of the KTY 84 thermistor changes proportionally to the winding temperature
change (refer to the following diagram).
Figure 5-1
The KTY 84 is evaluated in the converter whose closed-loop control takes into account the
temperature characteristic of the motor winding. When a fault occurs, an appropriate
message is output on the drive converter. When the motor temperature increases, a
message "Alarm motor overtemperature" is output; this can be externally evaluated. If this
signal is ignored, the drive converter shuts down after a preset time period or, when the
motor limit temperature or shutdown temperature is exceeded, the converter shuts down with
an appropriate fault message.
1PH4 Induction Motors
Configuration Manual, (APH4S), 08/2008, 6SN1197-0AD64-0BP1
Properties and technical specifications
Description
KTY 84 (PTC thermistor)
approx. 580 Ω
approx. 1000 Ω
Alarm at 120 °C ± 5 °C
Trip at 155 °C ± 5 °C
via signal cable
Resistance characteristic of the KTY 84 as a function of the temperature
5
89