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System Control Parameter and Setpoint Communication
The sequencer continuously sends the setpoint and system control parameter to all the compressors in its lead
list. Sending the setpoint eliminates the need to setup every compressor individually and allows the sequencer to
schedule setpoint changes. Sending the system control parameter eliminates any piping losses and assures that
all compressors are working towards the same goal. When a compressor is using the sequencer setpoint and
control parameter the setpoint will be displayed and the setpoint group label will be displayed as “SY.”
Sequencer Operations
The current operational status of a sequencer is displayed on the sequencer status page. The sequencer may be
in any one of the following states :
DISABLED
-The sequencer has been disabled and no staging will be performed.
HOLDING
-The sequencer is enabled and the system control parameter is currently within the
deadband.
DECREASING
-The sequencer is enabled and the system control parameter is below the unload
deadband. Stages will be removed based on the stage delay timers.
INCREASING
-The sequencer is enabled and the system control parameter is above the load
deadband. Stages will be added based on the stage delay timers.
Sequencer Lead List
The compressors available to a sequencer and the order in which they are to be used are defined in the sequencer
lead list. The operator can modify the lead list from the sequencer lead list screen. The total list of compressors
available to the sequencer is pre-defined based on the piping of your refrigeration system.
Unused Compressors in the Lead List
If the operator determines that a particular compressor should not be used, a NONE may be selected in any
of the lead list slots.
Swing Machines
In many refrigeration systems a compressor may be piped such that it is allowed to be used on more than one
refrigeration load. For example, using hand valves the operator may configure a compressor as a booster or
a high stage machine. In such a system this swing machine may be available to two separate sequencers.
The operator should take precautions to ensure that the name of the swing machine appears in only one
sequencer lead list.
Summary of Contents for Vilter VilTech
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Page 154: ...154 Alarm and Failure Data ...
Page 155: ...155 Alarm and Failure Data Continued ...
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Page 158: ...158 Compressor State Table ...
Page 159: ...159 Last RECIPStart Status Table ...
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