Monitor Functions - GE Bently Nevada 3300/25 Operation Manual

3300/25 Dual Accelerometer Input Monitor Operation Manual

2. Monitor Functions

DUAL ACCELEROMETER INPUT - The 3300/25 Dual Accelerometer Input Monitor
provides two independent channels of on-line machine monitoring using accelerometers
for the transducer inputs. Accelerometers are generally used for high frequency
measurements on machines such as turbines, gear boxes, compressors, and pumps.
The monitor has filtering capabilities (high-pass, low-pass, band pass) that are
programmable for selected frequency components or ranges.
SINGLE ACCELEROMETER INPUT - The 3300/25 Dual Accelerometer Input Monitor can
also be used with a single transducer input. In this mode you can use both channels to
monitor the same transducer but using different signal processing on each channel. You
can choose to have channel A display in acceleration units and channel B in velocity
units. You can also use different filter configurations on each channel.
OK - When the transducer output voltage is within the upper and lower OK limits of the
monitor, the transducer is defined as OK. The detection circuit controls the channel OK
and the monitor relay drive to the System OK Relay. If the monitor has the latching OK
option enabled, a system reset is required to reset the OK function.
TIMED OK/CHANNEL DEFEAT - Timed OK/Channel Defeat minimizes false alarms due to
faulty transducer wiring. If the input signal level on a given channel is not within the
upper and lower OK limits, the following events occur:
the OK LED for the channel goes off,
the BYPASS LED for the channel comes on,
the channel is disabled, and
the System OK Relay de-energizes.
If the channel input signal level is restored within the upper and lower OK limits for 30
seconds, the channel OK LED starts flashing at 1 Hz to indicate that the OK state is
restored, the BYPASS LED goes off, and monitoring is enabled. Press the RESET switch on
the front of the System Monitor to stop the OK LED from flashing (it will remain on and
steady after you press the RESET switch).
If the channel remains not OK, you can put the channel out of service by setting a
channel bypass switch on the monitor circuit board. The monitor can then be operated
as a single channel monitor. Without this feature the OK Relay could not be reactivated
when faulty transducer wiring causes a not OK condition. In the Timed OK/Channel
Defeat and Channel Bypass modes the recorder output is clamped to bottom scale and
the meter registers zero. If you select Timed OK/Channel Defeat, you must also set the
OK mode to nonlatching.
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