EVCO c-pro nano RACK - Manual (Page 57)

C-PRO NANO RACK E C-PRO MICRO RACK APPLICATION MANUAL
Page 57
Inverter consent with PWM
In some applications it can be necessary to command the consent of the inverters with a PWM output
configuring 0% or 100%. To use this option is necessary to operate with the same logic used in the previous
examples on the parameters HC0x, configuring the values according to this rule:
HC01 = 13 -> Defines that the PWM output on the controller is used for the consent
of the compressor with inverter of circuit 1
HC0x = 14 -> Defines that the PWM output on the controller is used for the consent
of the compressor with inverter or circuit 2
Note. Configurino the value 13 or 14, is used the related PWM, this means that the possibile parameters HC31,
HC32, HF31, HF32 should not be configured as PWM.
6.4.6 Compressors with different power
The management of compressors with different power could be useful to be able to more precisely regulate the
establishment of the final value compared to the configured setpoint.
To use this management, the related parameter, enable compressors of different power (PG03), must be enabled
and the parameters that represent the power of each compressor whose utilization is desired in the system must
be set.
The software calculates the maximum power able to be expressed from the single powers of the compressors;
according to the requirements of the regulators it calculates the best combination of compressors to deliver the
requested power. For a better regulation, the internal resolution of the step is multiplied by three; in this way, by
using compressors with different power, there are more combinations that can match the exact power requested
by the regulator.
At each variation of the request, the combination of compressors is recalculated in such a way as to produce a
power to be delivered that is equal or greater than that requested.
Compressors manually disabled, in alarm and under protections will not take part to the computation.
Note. Enabling this function, compressors subjected to throttling or compressors with inverters are not able to
be used.
Sideband Adjustment
Based on the parameters of adjustment (paragraph 2.3.1), the application will calculate the power necessary to
return the pressure/temperature detected in the proximity of the desired setpoint.
The required power will be calculated based on the proportional regulator or proportional + integral, while the
power supplied will be given by the combination of powers of the compressors that more closely exceeds what
is required.
Neutral Zone Adjustment
Based on the zone where the regulator is found, a new sequence of compressors to activate is calculated, and
more precisely:
- In the neutral zone: the combination remains unchanged.
- In the turn-on zone: the combination of compressors is recalculated in order to guarantee a power that is
greater than that supplied by the previous combination.
- In the shutdown zone: the combination of compressors is recalculated in order to guarantee a power that
is inferior to that supplied by the previous combination.
The recalculation of the combinations occurs based on the timings of the neutral zone: refer to paragraph 2.3.2.
Example
Consider 3 compressors of different power and a sideband adjustment of a proportional type, with these
parameters: