BRUEL & KJAER VIBROCONTROL 8000 - Engineering - Managing and Minimizing Alarms; Set Effective Time Delays

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6 Engineering - Managing and Minimizing Alarms
The VC-8000 rack has several features to help you manage alarms. Those familiar with plant control
rooms know that many of the alarms are initially questioned (i.e. Is it real?). Faulty wire connections,
faulty sensors, and faulty equipment often make false alarms more common than real alarms. The
following features (and recommendations) may help to improve the reliability of the alarms coming
from the VC-8000 system.
6.1 Set Effective Time Delays
All alarms have time delays. Typical delays for critical machines are 3 seconds for Alert alarms, and 1
second for Danger alarms. For balance of plant machines (and for troublesome sensors), a time delay
of 5 seconds for Alarm, and 3 seconds for Danger may make sense. This can help minimize alarms
caused by spikes or noisy signal lines etc.
6.2 Use Non-Latching Alarms, & Latching Relays
Most alarm management is performed at the DCS (or ESD/IPS). Operators will view, acknowledge
and reset alarms at the DCS, and go to the lower level device (VC-8000) if more information is
needed.
Using non-latching alarms in the VC-8000 will make the VC-8000 event list more useful. You will get
an event when the alarm annunciates, and a second event when the alarm goes away. This allows
you to establish the exact timing of the alarm when it occurs.
The VC-8000 trip relay should be latched. The relay is the action that was programmed to take place
based on the alarm. This can be latched and reset, by the operators, after the appropriate procedures
have been followed.
6.3 Increase Confidence with Regular Maintenance
Regular maintenance will increase plant personnel’s confidence in the VC-8000 system
(see section 2.4).
6.4 Install a Remote Reset
A remote reset command allows your operators to reset all latched alarms (and/or relays). You can
easily design a remote reset for the rack using the discrete contact on the RCM module or by sending
a Modbus ‘rack reset’ command.