SKF Multilog IMx-S Series User Manual page 28

Troubleshooting Guide
Sensor circuits
After a visual inspection, deeper troubleshooting of a sensor circuit requires the use of
suitable test equipment, minimum being a digital multimeter (DMM).
su h as se so
measuring DCV can in some circumstances significantly alter the circuit behaviour.
Be pa ti ula ly autious of usi g i st u e ts that ha e a lo i peda e
measure e t fu tio to si ulta eously test fo oltage o o ti uity a d e su e
the DCV measurement is being made in a high impedance mode.
Checking vibration channels
The following flow steps can generally be used to troubleshoot a 2-wire accelerometer
that is non-responsive. It is based on checking for the presence of a Bias Output Voltage
(BOV) in an acceptable or expected range.
1. Identify the input terminals where the channel in question is connected to the IMx-S
and measure the DC voltage between the sensor wires at the terminal block using a
digital voltmeter.
2. Is the measured voltage within the expected normal working range? For a typical
accelerometer this would be 8 to 12 V DC.
NO: Skip to step 3.
YES: The cabling to the sensor is probably OK and the sensor interface to the IMx-S
is normal. If the sensor output signal is still perceived as incorrect, then check the
transducer mounting and try substituting the sensor.
a. Did the fault remain after checking the mounting and changing the sensor?
3. Is the voltage close to zero (typical < ±0,5 V)?
NO: Skip to step 4.
YES: Now, verify that the voltage rises to normal open circuit voltage (about 24 V
DC) when one of the sensor wires is disconnected from the terminal block of the
IMx-S device.
a. Did the voltage rise to normal open circuit voltage?
b. The fault is in the sensor or its cable. Go to the sensor and disconnect the cable
5 - 2
Whe usi g test e uip e t to easu e ithi ele t o i
i i g, e a a e that e e si ple e uip e t su h as a DMM
NO: If substituting the sensor cleared the fault then the sensor was defective
and should be replaced.
YES: The fault may be in the analogue input section of the IMx-S device. Contact
TSG for advice and further information.
NO: The IMx-S is not providing sensor power. Check that the IMx-S is correctly
configured to supply sensor power for this channel. If properly configured,
then the IMx-S may be damaged. Contact TSG.
YES: Continue.
at this end. Reconnect the cable on the IMx-S terminal block and again
measure the voltage across the two terminals. Does the short circuit remain
(voltage close to zero)?
o t ol i uits
SKF Multilog On-Line System IMx-S
User Manual – Revision S