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4.
This configuration applies to varifan or water valve upon unit type. It is used to adjust the head pressure
control PID loop. Normally this decision has not to be modified for Varifan. For water valve it can be
adjusted upon water valve type and installation.
0.4
hd_sp_dg
Derivative PID Gain:
0.4
hd_sp_ig
Integral PID Gain:
2.7
hd_sp_pg
Proportional PID Gain:
Recommanded for air
cooled
PDI GAINS
2.0
hd_sp_dg
Derivative PID Gain:
0.2
hd_sp_ig
Integral PID Gain:
2.0
hd_sp_pg
Proportional PID Gain:
Recommanded for
water cooled
PDI GAINS
5.
Upon the operating capacity, the discharge superheat is adjusted as follows :
discharge superheat control point = se 3.8^C (7^F) if no loader ON.
discharge superheat control point =se 1.7^C (3^F) if one loader ON.
discharge superheat control point =setpoint if both loaders ON.
6.
This setpoint is used by the EXV control in order to maintain an optimal cooIer exchange delta temperature
between leaving temperature and saturated suction temperature. This is done in compensation with
discharge superheat temperature which has higher priority.
7.
This decision allows to set the high pressure override threshold:
w
If the saturated condensing temperature is greater than [the maximum condensing temperature override
threshold minus the maximum condensing temperature override differential] but less than the [maximum
condensing temperature threshold] then the capacity increase shall be inhibited.
w
If the saturated condensing temperature is greater than the [maximum condensing temperature override
threshold] then one stage capacity of the corresponding circuit shall be removed (doesn't apply to the last
stage).
8.
This decision allows to set the high current override threshold:
w
If the compressor current is greater than [the maximum current setpoint threshold minus the maximum
current override differential] but less than the [the maximum current setpoint threshold] then the capacity
increase shall be inhibited.
w
If the compressor current is greater than [the maximum current setpoint threshold] then a loader of the
circuit or the compressor will be stopped.
w
curr_max and curr_dif are in percent of MTA (Must Trip Amps). curr_max shall not exceed 85% as the
screw compressor board shall stop the compressor for alarm when current reaches 85% of MTA.
9.
The Global chillers use compressors which have better performance at full load than at part load.
Therefore the loading sequence strategy will be different from the one for flotronic II or pro-dialog 30 G & H
control. When compressor is on, it will try to avoid the compressor operate at low capacity (no loader ON).
If this item is
enable
, the control will use any stage of capacity in order to keep the exchanger leaving
temperature as closed at possible to the control point what ever the compressor performance. When the
circuit is in capacity override (compressor status LEDs in the synopsis are blinking), the control will force
the close control capacity variable to enable until the circuit is no more in override.
©
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CARRIER SA
USER'S GUIDE FOR
30GX&HX PRO_DIALOG 4 V.2
ECG - UG - 02 - 02
Rev: Original
Page: 26 /98
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