See the firmware manual for information on the related Motor thermal protection function,
and the required parameter settings.
PTC connection 1
1…3 PTC sensors can be connected in series to an analog input and an analog output.
The analog output feeds a constant excitation current of 1.6 mA through the sensor.
The sensor resistance increases as the motor temperature rises, as does the voltage
over the sensor. The temperature measurement function calculates the resistance of
the sensor and generates an indication if overtemperature is detected. Leave the sensor
end of the cable shield unconnected.
1…3 PTC sensors1
Analog input. Set the analog input type to V (volt) in parameter group 12 Standard AI. Define
the temperature sensor type, signal source, etc. with parameters 35.11…35.24. For the
sensor type, select: PTC analog I/O.
2
Analog output. Select the Excitation mode for the analog output in parameter group
13 Standard AO.
3
PTC connection 2
If no analog output is available for the PTC connection, it is possible to use a voltage
divider connection. 1…3 PTC sensors are connected in series with 10 V reference and
digital and analog inputs. The voltage over the digital input internal resistance varies
depending on the PTC resistance. The temperature measurement function reads the
digital input voltage through the analog input and calculates the PTC resistance.
Electrical installation – IEC 79
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