EVCO c-pro mega RACK - Manual (Page 84)

C-PRO MEGA RACK & C-PRO GIGA RACK APPLICATION MANUAL
Page 84
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In the neutral zone: the combination remains unchanged.
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In the on zone: the combination of compressors is recalculated in order to guarantee power
greater than that provided by the previous combination.
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In the off zone: the combination of compressors is recalculated in order to guarantee power
less than that provided by the previous combination.
The recalculation of combinations is implemented on the basis of the neutral zone time settings,
please refer to section 6.4.5.
Example
Considering 3 compressors of different nominal power ratings and a side band proportional
regulation device, with the following parameters:
Setpoint = 0.5 bar
Proportional band = 2.0 bar
Compressor 1 power = 3 kW
Compressor 2 power = 5 kW
Compressor 3 power = 10 kW
Below the setpoint, no power is delivered, above the setpoint plus the band, the power delivered is
the maximum available.
6.4.10 Suction line loss of load compensation
In certain systems, it might become necessary to reduce the suction setpoint with increased
refrigerant capacity, in order to compensate for the increased pressure loss along the suction line. In
practice, the services, which should operate at constant evaporation pressure, are forced to operate
higher pressures when the cold requirement is greater, and vice versa. This means that, in order to
guarantee cold production at the desired temperature, even with loads approaching the nominal
values, it is necessary to work with a significantly lower setpoint even at partial loads, when this
should not be necessary. Compensation works by introducing a configurable offset that lowers the
setpoint, gradually, with each demand for cold steps: it is clear that this function has the aim of
increasing system efficiency, allowing the selection of a higher setpoint at low loads.
The parameter PH35 enables this function, lowering the setpoint by a compensation factor (PH36
Suction load compensation offset) with each step inserted, and raising the same value with each step
released.
This function can only be activated with neutral zone regulation.
Measured Pressure
(bar)
Required Power
(kW)
Compressor 1
(3 kW)
Compressor 2
(5 kW)
Compressor 3
(10 kW)
Power Delivered
(kW)
0.5 - 0
0.6 0.9 X 3
1.0 4.5 X 5
1.3 7.2 X X 8
1.6 9.9 X 10
1.7 10.8 X X 13
2.0 13.5 X X 15
2.3 16.2 X X X 18
2.5 18 (max) X X X 18 (max)