INSTALLATION AND OPERATING INSTRUCTIONS
Troubleshooting
SKF Multilog On-line System IMx-8/IMx-8Plus
User Manual
Revision E
39 (63)
properly configured, then the IMx device may be damaged. Contact
TSG.
YES: Continue.
b. The fault is in the sensor or its cable. Go to the sensor and
disconnect the cable at this end. Reconnect the cable on the IMx
terminal block and again measure the voltage across the two
terminals. Does the short circuit remain, with the voltage close to
zero?
NO: The sensor is defective. Replace the sensor.
YES: The sensor cable or contact/connector, has a short circuit and
requires repair/replacement.
4. Is the voltage close to the open circuit voltage?
YES: There is an open circuit in the cable or the sensor is damaged. Skip to
step
NO: If the voltage appears to be neither within the normal working range,
close to zero nor close to the open circuit voltage, then the fault is an unusual
one. First, recheck that the DCV measurement was correctly carried out, then
contact TSG for advice.
Remaining faults can be due to a damaged sensor or a damaged IMx input
circuit. First, disconnect one pole of the sensor cable and measure the open
circuit voltage to verify whether the open circuit voltage is normal (about 24 V
DC). If it is normal, then the fault is probably in the sensor, otherwise the fault
is likely in the IMx.
5. Disconnect the connector from the sensor and short circuit the pins in the
sensor contact, then re-measure the voltage on the IMx terminal block. Did
the voltage sink to close to zero (<0.5 V)?
NO: There is an open circuit in the cable. Repair/replace the cabling.
YES: There is an internal open circuit in the sensor or there is a bad/oxidised
contact. First, try cleaning the contact before replacing the sensor connector
and checking again.
2.9.3.2 Checking 4-20 mA channels
In case of unexpected measurement values, check the channel configuration
especially scale, zero level and choice of engineering units.
Confirm that the signal applied is a 4-20 mA and not for example 0 to 20 mA. Also,
be aware that some 4-20 mA devices will set their outputs low (typically 2.9 mA) or
high (typically 21 mA) to signal a sensor/circuit failure. In such circumstances the
output current will be different to the source, measurement value.
Channels where the input signal is 4-20 mA, should have an SKF provided, 250-ohm
load resistor fitted, refer section
