Ipg215D Controller - Functionality; Suction Pressure Control; Figure 32: Switching From Transcritical To Subcritical Mode - Emerson Copeland OME-4MTL-12X Application Manuallines

2.11 IPG215D controller – Functionality
The IPG215D controls the complete refrigeration unit. It provides a lot of customization features like
alarms and special operating modes. Thanks to the high degree of flexibility, the user can either use
the factory-set alarms or set up his own alarms according to the application requirements.
The following functionalities are pre-programmed:

▪ suction pressure control

▪ fan speed / gas cooler control
▪ alarms
The refrigeration unit is able to operate in both subcritical and transcritical modes. The setpoint for
switching from subcritical to transcritical operation is adjustable (GC1). The factory setting for this
trigger point is 27 °C, measured over gas cooler outlet sensor B7 (AIC7). The (adjustable) hysteresis
(GC2) for the (GC1) setpoint is 1 K.

Figure 32: Switching from transcritical to subcritical mode

NOTE: A system control very close to the critical point may result in a loss of capacity and
unstable system behaviour. This can be overcome by setting GC3 to a higher value (76-80 bar)
or by dynamic offset using parameters GC16 and GC17.
2.11.1 Suction pressure control
2.11.1.1 Standard suction pressure control
The setpoint for suction pressure control is parameter SETC1, the factory setting is -10 °C.
SETC1 Compressor Circuit 1 setpoint
Range: -15 to -5 °C
Unit: (°C)
Depending on the number of evaporators, ie, on the suction side internal volume, a rapid decrease
of the suction pressure during compressor start might occur. This can result in low-pressure cut-out
before reaching stable regulation conditions. The acceleration of the compressor speed can be
adjusted by decreasing the value of SETC1.
2.11.1.2 Automatic pumpdown
If parameter SPF4 is set to "yes" a pumpdown will be performed before stopping the compressor. If
it is set to "no", only the manual pumpdown and the automatic pumpdown during the bypass
optimization function will be performed.
SPF1 Compressor setpoint during pumpdown
Range: -70 to -10 °C
Unit: (°C)
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