Pumpdown configuration generates an alarm in the controller and performs a
pumpdown procedure to stop the unit.
4.10 Power Conservation
In this chapters will be explained the functions used to reduce the unit power consumption:
1. Demand Limit
2. Setpoint Reset
4.10.1 Demand Limit
The “Demand limit” function allows the unit to be limited to a specified maximum load. Capacity limit level is regulated
using an external 4-20 mA signal with a linear relationship shown in the picture below. A signal of 4 mA indicates the
maximum capacity available whereas a signal of 20 mA indicates the minimum capacity available. In order to enable this
option, go to Main Menu Commission Unit Configuration Options and set the Demand Limit parameter to
Yes.
Graph 1 Demand Limit[mA] vs Capacity Limit[%]
It is worth pointing out that it is not possible to shut down the unit using the demand limit function, but only to unload it to
its minimum capacity.
Note that this function does a real capacity limitation only if the unit is equipped with Screw compressors. In case of Scroll
compressors, the demand limit operates a discretization of the overall unit capacity according to the actual number of
compressors, and, depending on the external signal value, it enables only a subset of the total number of compressors, as
shown in table below:
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