INSTALLATION AND OPERATING INSTRUCTIONS
Troubleshooting
SKF Multilog On-line System IMx-8/IMx-8Plus
User Manual
Revision E
Deeper troubleshooting requires the use of suitable test equipment, minimum being a
digital multimeter (DMM).
2.9.3.1 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 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 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?
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
device. Contact TSG for advice and further information.
3. Is the voltage close to zero, typically < ±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 device.
a. Did the voltage rise to normal open circuit voltage?
NO: The IMx is not providing sensor power. Check that the IMx is
correctly configured to supply sensor power for this channel. If
When using test equipment to measure within ‘electronic control circuits’
such as sensor wiring, be aware that even ‘simple’ equipment such as a DMM
measuring DCV can in some circumstances significantly alter the circuit
behaviour. Be particularly cautious of using instruments that have a ‘low
impedance measurement function to simultaneously test for voltage or continuity’
and ensure the DCV measurement is being made in a high impedance mode.
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