AI and AO (or AI, DI and +10 V) as PTC motor temperature sensor interface
WARNING!
IEC 60664 and IEC 61800-5-1 require double or reinforced insulation between
live parts and accessible parts when:
• the accessible parts are not conductive, or
• the accessible parts are conductive, but not connected to the protective earth.
Obey this requirement when you plan the connection of the motor temperature
sensor to the drive.
If the motor temperature sensor has a reinforced insulation vs. the motor windings, you
can connect it directly to the drive IO interface. This section shows two connection
alternatives for the direct I/O connection. If the sensor does not have reinforced insulation,
you must use another type of connection to fulfill the safety requirements. See
Implementing a motor temperature sensor connection (page 56).
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
Electrical installation – North America 103
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