Standard Screw Compressor - RWB Series
2-18
M&M
R
EFRIGERATION
I
NC
.
Alarms & Failures
The CCS continually monitors the system parameters and compares them to alarm and fail-
ure setpoints to inform the operator of the system status. An alarm is intended to alert the
operator that an undesirable condition exists. A failure is an indication that a more severe sys-
tem condition exists and may cause the system or component to shutdown. The system
parameters are compared to both operator-defined setpoints, and M&M Original Equipment
Manufacture (OEM) safety setpoints. An alarm or failure is detected when a system parame-
ter is outside the acceptable range of the setpoints.
Certain alarms and failures may also be suppressed under specific conditions. For example,
the low oil pressure alarm is suppressed when the compressor is not running. Additionally, the
detection of certain alarms and failures can be delayed. For example, the low suction pres-
sure failure is delayed for 10 seconds, in other words the suction pressure must be below the
low failure setpoint for 10 consecutive seconds before the system is shutdown.
Some alarm and failure setpoints are assigned factory default values, which may not be
changed by the operator. These are called OEM safety setpoints and typically indicate a con-
dition that may cause damage to the equipment. A detailed list of all system alarms and fail-
ures can be found in Appendix A.
When an alarm or failure is detected the sequence of operations is as follows:
The equipment controlled by the CCS may be stopped, as in the case of a compressor, when
a failure occurs.
The alarm or failure is entered into the active alarm and failure list and the current status
screen on the display is replaced with the active alarm and failure screen.
An entry is made in the appropriate alarm or failure log.
A special entry is made in the operation and trend logs listing the parameter values at the time
of the alarm or failure.
The current alarms and failures present on a system can be viewed on the active alarms &
failures status screen. The operator must acknowledge and clear alarms/failures from this
screen or the main status screen using the procedures covered in this section.
When a new alarm or failure becomes active, the Active Alarm & Failure status screen will be
displayed as the default status screen. The user can view all of the active alarms by scrolling
through the alarms using the up and down arrow keys. An example of the alarm & failure sta-
tus screen is shown below.
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