1
PARAMETERS
This chapter presents the parameters relevant for sequence control system.
The sequence control for packages is set up so that the local control for each unit is active. The sequence mod-
ule overrides the local control on certain units in relation to the current running condition. These units are then
not controlled by their setpoints and process values but by the sequence module.
1.1
Explanation of the parameters of local control
Operation mode
Required operation mode
Operation modes 0, 1, 2, 5 and 9 are not permitted.
Process value
Process value that should be controlled, e.g. suction pressure,
external temperature, discharge pressure
Setpoint
°C
Setpoint for capacity control
Neutral zone
K
As soon as the process value is within this zone, the compressor
capacity is not changed. Exception is if a capacity limitation
becomes active, then the controller can change the capacity. The
zone lies symmetric around the setpoint.
The value must be less than the value for the proportional zone (see
1.1.2 "Capacity control of reciprocating compressors").
Auto start delay
secs
Initiated by process value rising above Neutral Zone
and compres-
sor not running.
Auto stop delay
secs
The auto stop delay occurs only when the relevant compressor in
the sequence is active.
The auto stop delay is initiated by process value falling below Neu-
tral Zone
and compressor running with Part Load or less
capacity and only one compressor in the sequence is active.
1.1.1
Screw compressor capacity control
Hysteresis
K
Area at the boundary of the neutral zone where in dependence of
the direction of the process value change the capacity control does
not change the compressor capacity.
Load pulse
secs
Pulse time for capacity increase.
Unload pulse
secs
Pulse time for capacity decrease.
Operating Manual | Sequence Control for Packages
GSC TP
Parameters
GEA Refrigeration Germany GmbH | E_301510_2 | Generated 17.12.2014
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