Vertiv Liebert PCW - Starting and Stopping; Automatic Restart; Operation

14Liebert PCW - UM - 273895 - 04.10.2018
3) Bleed all air out of the chilled water circuit using the bleed valve
on the chilled water coil (left side for single chilled water circuit,
left+right side for double chilled water circuit).
4) Close all MCBs on the electrical panel.
5) Check the supply voltage on all phases.
6) Start the unit by pressing ON/OFF button on the external
display (on the internal display if the external display isn’t installed).
7) Check the electrical absorption of all components (see Chap. 6).
8) Ensure that all control system settings are correct and that there
are no alarms (see Control manual).
9) Verify the water ow.
10) Verify the Fresh Air Intake operation (if tted).
11)Once the system is operating under load, check the various
components, as follows:
• Verify that the fans are operating properly.
• Ensure that the temperature and relative humidity are being
controlled, and that the humidier (optional) and heating steps
(optional) operate when required.
• Ensure that chilled water valve operates when required.
7.2 - Starting and stopping
Turn on the unit operating on the ON/OFF button on the display.
The fan starts immediately (the fan always works when the unit is
ON); after 2 minutes the regulation is activated, so the cooling ,
heating (electric heaters), humidifying and dehumidifying devices
can start.
Adjust the set- point as indicated in Control manual.
Stop the unit putting the ON/OFF switch in OFF.
• The main switch on the electrical panel inside the unit should
be switched o󰀨 if the unit is stopped for a long time.
7.3 - Automatic restart
If desired, the unit will automatically restart on the return of power
after a supply interruption (see Control manual).
8 - Operation
Unit operation is completely automatic. The below sequence ex-
plains how the unit operates :
• The air, sucked in by the fan, enters the unit.
• The air is immediately ltered.
• The TEMPERATURE Sensor or HUMITEMP (temperature +
rel. humidity) Sensor (check type installed), veries the state
of the inlet air, and relays this information to the control sys-
tem.
• The control system compares the relayed information to the
set point and proportional band values programmed: it then
commands the air conditioner to treat the air as follows (see
also Control manual):
• COOLING
Chilled water ows through the chilled water coil, thus cooling
the air passing over it. The chilled water ow is controlled by a
timed modulating (3- way) valve, which regulates the ow rate
in order to obtain the exact amount of cooling required.
• HEATING
This can take one of two forms:
• Electrical heating (optional): the heating elements heat
the air passing over them.
• Hot water heating (optional): if hot water is available, this
ows through the hot water coil, thus heating the air pass-
ing over it. The hot water ow is controlled by an on- o󰀨
3- way valve.
• Dual Power Supply - Optional
This option allows a supply of electrical power from two dif-
ferent electrical sources. It is available the following solution:
• Dual Power Supply Alternate Premium Version: all the
functions provided by the basic one with addition of the
following premium benets:
• Possibility to have together Automatic and Manual
change over.
• Faster switching between power A and power B.
• Higher exibility on conguration of the operation.
• Possibility to select the preferred line.
• Possibility to select voltage and frequency ranges to
make the switch.
• Possibility to select timing for switching.
• DEHUMIDIFICATION - optional
Maximum chilled water ow is requested through the coil,
whose temperature drops below the dew point of the air, thus
dehumidifying it.
If necessary, heating is used to reheat the air.
N.B.: If, during dehumidication, the room temperature drops
below a specied level, dehumidication could be stopped
(see LOW LIMIT intervention in Control manual).
• HUMIDIFICATION - optional
The humidier creates steam, which is distributed into the air
stream via the steam distribution pipe (see also Enclosure A).
• Filtered new air is injected into the air stream via the Fresh
Air Intake.
• The treated air passes through the fans, which operate contin-
uously, and is then dispersed out of the unit.
• Downow Up and Downow Down units only: the air passes
from the underoor into the room via air distribution outlets.
For Downow units: switch o󰀨 the machine before remov-
al of the oor panels within a distance of 850 mm from the
machine, to avoid risks of contact with rotating devices
(fans) moving and with hot heating elements.