Stulz C7000 - Differential pressure control

133 © STULZ GmbH – all rights reserved EN/06.2019/G57
C7000 INSTRUCTIONS fOR A/C UNITS
6.5 Differential pressure control
The differential pressure control has the second highest priority as
far as the fan speed control is concerned. The differential pressure
control will be interrupted for emergency operation of the fan.
The pre-condition for this control is that at least one A/C unit in a
zone is equipped with a pressure sensor.
This sensor must be calibrated in the menu D1.
In case of several sensors, enable the calculation of average values.
The differential pressure control is enabled by a value in menu D2
which is different from zero.
The control tries to keep the adjusted setpoint for the surpressure in
the raised floor or in the cold aisle compartment.
The control of the room air pressure is a special form of DFC²
control.
For this control a proportionally controlled fan with an analog output
has to be configured (Setting: LINEAR).
The control begins after the lapse of the "START 100%" time and
the pre-run time in menu D5 with the maximum speed (max. speed).
An offset value, which serves to adapt the air volume flow to local
conditions will not be considered.
Maximum speed serves only as an initial value for the control which
starts now by measuring the difference to the air pressure setpoint
and reduces the fan speed in case of exceeding the setpoint and
increases fan speed when the setpoint is passed under.
By three parameters (cycle, maximum control modification and cont-
rol factor) the characteristics of an integral control are achieved.
The adjusted minimum speed is not passed under during control.
With enabled differential pressure control only the DX values "min.-
speed" and "max. speed" are effective for the fan.
All speed increases or reductions for the fan are put out of force.
After the unit stop the fan runs during an overrun time, which serves
to reject hot or cold air in the unit.
sensor ## use 47
setapress ##
zone ## avgp 1
Config/Components/Sensor
(D1)
Operate/Values/Air/Pressure
(D2)
Config/Components/Air/Fan/
General (D3)
Config/Components/Air/
Fan/Special (D5)
supply air press. in cPa