GE Bently Nevada 1900/27 Operation And Maintenance Manual page 9

Programmable options provide flexibility and a wide range of standard features.
Internal Jumper Options:
Normally Energized/De-energized Relays - The Alert and Danger relays can
be be either normally energized or normally de-energized. The normal
condition of a relay corresponds to its non-alarm condition. For example, a
normally energized relay would have power on the coil (ARM contacts NO)
when it is not in alarm and would remove power from the coil (ARM
contacts NC) when it goes into alarm. Both relays are independently set.
Latching/Nonlatching Relays - The Alert and Danger relays can be either
latching or nonlatching. Latching alarms must be cleared using the reset
button or by closing a switch between the reset terminals. Nonlatching
alarms automatically reset when the monitor no longer detects an alarm
condition. Both relays are independently set.
4 to 20 mA Interface Behavior during BYPASS - When the monitor is
switched to BYPASS, the 4 to 20 mA output sends approximately 2 mA to
the host computer. Since some applications require dynamic data collection
during BYPASS, you can set the monitor so that it collects data even when
the alarms are bypassed.
Front Panel 6-position Configuration Switch Options:
Relay Time Delay - The Alert and Danger relay time delays can be set for 3,
5 , 10, or 15 seconds. Relay time delay is the amount of time that the
vibration level must be greater than the alarm setpoint level before an alarm
trips. The time delay minimizes false alarms from either "normal" transient
vibration or electrical noise sources. The relay time delay setting applies to
both relays as long as both are configured to activate under an alarm
condition.
Alert Relay Configuration - To help you use the monitor for different
applications, the Alert relay can be set to activate under any of the
following conditions:
Alert
Alert or NOT OK
NOT OK
Danger (as an auxiliary Danger relay)
Units - You can set the overall vibration level shown on the LCD display to
display in either English (in/s) or metric (mm/s) units. Both units are true
zero to peak measurements, not RMS measurements converted to peak.
Monitor Self Test - A user-invoked self test switch is provided to aid in field
troubleshooting. When you invoke the self test, the signal path and alarm
threshold detection circuits are verified. All LEDs and LCD numerical
Section 1 - 1900/27 Vibration Monitor Description
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