ABB DriveIT ACH550-UH - Page 108

108 ACH550-UH User’s Manual
Start-Up
The figure below shows alternate thermistor connections. At the motor end the cable
shield should be earthed through a 10 nF capacitor. If this is not possible, leave the
shield unconnected.
For other faults, or for anticipating motor overheating using a model, see Group 30:
Fault Functions.
Group 35: Motor Temp Meas
Code Description Range Resolution Default S
3501 SENSOR TYPE 0…6 1 0
Identifies the type of motor temperature sensor used, PT100 (°C) or PTC (ohms).
See parameters 1501 and 1507.
0 =
NONE
1 = 1 x PT100 – Sensor configuration uses one PT 100 sensor.
• Analog output
AO1 or AO2 feeds constant current through the sensor.
• The sensor resistance increases as the motor temperature rises, as does the voltage over the sensor.
• The temperature measurement function reads the voltage through analog input
AI1 or AI2 and converts it to
degrees centigrade.
2 = 2 x PT100 – Sensor configuration uses two PT 100 sensors.
• Operation is the same as for above 1 x PT100.
3 = 3 x PT100 – Sensor configuration uses three PT 100 sensors.
• Operation is the same as for above 1 x PT100.
4 =
PTC – Sensor configuration uses one PTC.
• The analog output feeds a constant current through the sensor.
• The resistance of the sensor increases sharply as the motor temperature
rises over the PTC reference temperature (T
ref
), as does the voltage over
the resistor. The temperature measurement function reads the voltage
through analog input
AI1 and converts it into ohms.
• The figure shows typical PTC sensor resistance values as a function of
the motor operating temperature.
Motor
T
Thermistor
relay
OMIO board
DI6
+24 VDC
Motor
T
10 nF
Thermistor (0)
OMIO board
DI6
+24 VDC
100
550
1330
4000
Ohm
T
Temperature Resistance
Normal 0 … 1.5 kohm
Excessive >
4 kohm