GE Bently Nevada 3300/25 Operation Manual page 9

Section 2 - Monitor Functions
OK RELAY - The System OK Relay is mounted on the Power Input Module. Every channel
in the rack must be OK or bypassed to energize the OK Relay.
ALARM - Pressing the ALERT or DANGER switches on the monitor front panel causes the
corresponding Alert (first level alarm) or Danger (second level alarm) setpoints to be
displayed on the front panel meter. ALERT and DANGER LEDs come on when the signal
level exceeds preset levels for the selected time delay. The appropriate Alert and Danger
relay contacts are then activated. AND and OR voting logic options determine when the
Danger relay contacts are activated.
FIRST OUT - Separate First Out circuits exist for Alert and Danger alarms. A monitor with
the First Out option selected flashes a channel alarm LED if that channel was the first
channel in the rack to go into alarm since the last rack power up or reset. Pressing the
RESET switch on the System Monitor acknowledges the First Out (the LED stops flashing
and remains on steady).
DANGER BYPASS - When maintaining the monitor, you can set the Danger Bypass switch
on the monitor circuit board to inhibit the Danger relay drive. This function turns on the
BYPASS LEDs. Other front panel functions are not affected. You can enable this function
by installing a jumper on the monitor circuit board.
ALARM RELAYS - You can program monitor alarms for either latching or nonlatching
mode. In the nonlatching mode, the alarm resets automatically when the alarm
condition no longer exists. In the latching mode the alarm must be reset manually by
pressing the RESET switch on the front panel of the System Monitor (or by closing
external Reset contacts). The alarm will not reset if the alarm condition still exists.
BUFFERED OUTPUT - The monitor provides buffered signals from the transducers on the
channel A and B coaxial cable connectors on the front panel of the monitor and on
terminals on the Signal Input Relay Module. These connectors can be used to connect
external equipment to the monitor. The buffered output signal is in the same units as the
LCD display for that channel. For example, if a channel is displaying velocity units then
the corresponding buffered output will be in velocity units. The buffered output can also
be configured to output the filtered or unfiltered signal on a channel for which filters
have been configured, except for a channel which displays velocity and has the filters
before the integrator/gain stage.
RECORDER OUTPUT - The monitor provides a recorder output for each channel. The
recorder output is proportional to the measured acceleration or vibration signal over the
monitor full scale range. The output range is user selectable to be 0 to -10 Vdc, +1 to +5
Vdc, or +4 to +20 mA.
The recorder clamping option, available when the +4 to +20 mA recorder output is
selected, allows the user to choose the recorder output level used to annunciate a
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