GE Bently Nevada 1900/27 Operation And Maintenance Manual page 42

1900/27 Vibration Monitor Operation and Maintenance Manual
Problem
The LCD is blank, except
for the leftmost digit
isdisplaying a 1.
The relays do not appear to
activate when the vibration
exceeds the setpoint
Or
The annunciator or
machine that the relay is
connected to is not
affected by an alarm
condition at the monitor.
The 4 to 20 mA interface
sends an inaccurate signal
or no signal.
The 4 to 20 mA interface
indicates a "NOT OK"
(output is 1 to 3 mA) but
the monitor's OK LED is
on.
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Possible Solution
The input to the LCD circuit is above full scale. Check
•
the input vibration with a portable vibration analyzer, or
the buffered transducer output to verify that the
vibration is higher than 1.999 in/s.
Verify that the setpoints are set properly.
•
Make sure that the monitor is not in Bypass (BYPASS
•
LED is off) and that the OK LED is illuminated.
If the Alert relay is the problem, then verify that the
•
drive condition for the relay is properly set on the
Configration DIP switch.
Test the relay. Before testing either relay disconnect it
•
from any machinery that would be affected by the relay
changing state. To test the relay, lower the setpoint
below the current vibration level and verify that the
relay goes into its alarm state.
Verify that the cable between the monitor's relay
•
terminals and the device the relay is connected to is
correct. If the relay is being used to drive an external
relay or device, such as a motor control relay or a
buzzer, then verify that the external relay or device is
working properly.
Check the 4 to 20 mA interface cable for opens and
•
shorts between the 1900/27 monitor and the plant
computer.
Check that the plant computer power supply and loop
•
resistance meet the specifications listed in Appendix A,
Section 1.9.
Check calibration of the 4 to 20 mA interface according
•
to the procedures in Section 4.2.2 of this manual.
Verify that the bypass mode jumper (W4) is in and that
•
the monitor is bypassed. If these two conditions exist
then the monitor is operating correctly. When the W4
jumper is installed the 4 to 20 mA output will indicate a
"NOT OK" when the monitor is bypassed.