Hitecsa Advance EQS Serie Manual Del Usuario página 75

Low overheating alarm threshold (LowSH). If overheating drops below the
1
set threshold, the integral PID time is modified to make it more reactive and
after a time limit the low overheating alarm is triggered.
High operating pressure (MOP) alarm threshold
2
High operating pressure (MOP) alarm bypass in relation to circuit activation
3
On screen Jj31..Jj34 it is possible to set the valve opening percentage at start-up
(EEV Ratio). Note that this parameter is used together with the power percentage
to be switched on to determine the valve's opening position.
E.g.: in a two-compressor circuit, with EEV Ratio setting equal to 50% and with a
valve regulating from 50 to 480 steps, the unit switches on the first compressor
(50% of circuit power) opening the valve at [Minimum opening] + [50% x 50% =
25% of the operating range].
The EEV ratio percentage to be used in cooling mode does not have a
fixed value, but variable according to the output temperature of the heat
exchanger
primary. The colder the water, the lower the percentage of EEV ratio. To
by obtaining this shifting value the EEV ratio threshold is defined when the
temperature of -8°C and +7°C; the percentage is then calculated
interpolating the straight line that passes through these two points, up to the limit
of -10°C and
+15°C.
Percentage of EEV ratio in cooling by primary outlet temperature equal to -
1
8 ° C
Percentage of EEV ratio in cooling by primary outlet temperature equal to
2
+7 ° C
On screen Jj41..Jj44 it is possible to set the proportional, integrative and
derivative settings of the PID algorithm that controls valve opening in normal
regulation. To make the valve more reactive, you must increase the proportional
gain and the drift time or decrease the integrative time. To make the value more
stable, you must change the parameters in reverse.
On screen Jj51..Jj54 one sets the delays related to overheating and pressure
remaining over the alarm thresholds for triggering the alarm.
USM_CONTROL EQS_2335a21275_208549_210701_ES-EN-FR-DE-IT
On screen Jj61..Jj64 one sets threshold and delay of the intake low temperature
alarm.
1
2
3
On the user (evaporator) side of units with heat exchanger with flooded type shell
and tube, it is necessary to manage the amount of refrigerant through a level
valve.
On screens Jj81..Jj86 the parameters are set to manage an electronic valve that
controls the level of refrigerant in the flooded heat exchanger. Based on
manufacturer choice, three types of level valve adjustments are possible:
1
2
On screen Jj83 and following, if there is a second circuit, the proportional,
integrative and derivative parameters of the PID algorithm are set, that controls
valve opening in normal regulation. If prevention is active, the integral time takes
on the PID Ti value (prev.).
On screen Jj85 and following, if there is a second circuit, the parameters to
manage high subcooling prevention are set.
If the level valve is regulated by sliding subcooling control, the Jj87..Jj90 masks
are added to the Jj83..Jj86 masks that allow you to adjust the subcooling control,
which allow you to change the subcooling set-point based on the 'approach.
The level valve controls with a PID algorithm to maintain the subcooling set-point
on the circuit. The subcooling set-point, however, is not fixed, but is dynamic
because it is recalculated according to the operating conditions of the machine,
mainly according to the pressure ratio (difference between high pressure and low
pressure), based on the evaporator approach and, for the inverter compressor only,
the working frequency.
The approach is defined as the average between inlet temperature and the outlet
temperature from the evaporator minus the conversion into temperature of the
pressure measured on the compressor intake line.
97
III.1.10.2 EEV for level valve management

regulation based on a level sensor;

through the subcooling control;

through a shifting subcooling control;
Valve percentage set-point, if level valve control enabled based on the level
1
sensor. Subcooling set-point to be maintained during operation, if
subcooling control is enabled. If the shifting subcooling control is enabled,
the subcooling set-point is defined in screen Ji91 and following.
Minimum valve opening percentage in regulation
2
Maximum valve opening percentage in regulation
3
Valve shut-down percentage at circuit switch-on
4
Delay between compressor switch-on and start of PID regulation
5
High subcooling prevention temperature activation threshold
1
High subcooling prevention temperature disabling threshold
2
High subcooling prevention pressure activation threshold
3
CONTROL EQS
1
2
3
4
5
1
2
3