LIEBERT® OUTDOOR CONTROL ENCLOSURE™
Quick Installation Guide
3
590-1734-501A/SL-10060_REV5_9-17
• Install extra-low-voltage control
wiring (24 V) from Terminals
70 and 71 on the wire raceway
in the compressor
compartment of the indoor unit
to Terminals 70 and 71 of the
control enclosure.
• Install extra-low-voltage control
wiring between Terminals
24 and 50 from the control
enclosure to the indoor cooling
unit’s common alarm or other
alarm location for loss-of-flow
indication.
• Install extra-low-voltage control
wiring between the auxiliary
terminals on the control panel
to Terminals 70 and 71 on the
drycooler.
• Connect the flow switch wiring
to Terminals 77 and 74.
• Provide line voltage to power
block(s) in the control
enclosure as shown in the
electrical schematic.
• Install optional field-supplied
disconnect if desired.
• Run 3 -phase line voltage from
the control box to each
individual pump motor.
FLOW SWITCH
INSTALLATION
NOTE:
Only required for dual-
pump package installation.
• Mount the flow switch in a
section of coolant supply/
return piping where there is a
straight run of at least five (5)
pipe diameters on each side of
the flow switch.
• Mount the switch so the
terminals or wire leads are
easily accessible for wiring.
• Mount the flow switch in a
standard 1-in. x 1-in. x 1-in. tee
for one -inch pipe installation.
Use a reducing tee for larger
sizes of pipe to keep the flow
switch near the pipe and to
provide adequate paddle
length in the flow stream.
• Screw the flow switch in
position so the flat part of the
paddle is at a right angle to the
flow. The arrow on the side of
the case must point in the
direction of the flow.
• The flow switch must be
mounted in a horizontal
pipeline.
DUAL PUMP CONTROLS
SEQUENCE OF OPERATION
On a call for cooling, the
compressor contactor and/or the
Econ-O-Coil relay in the Liebert
unit is energized. The relay and
contactor are in the Liebert indoor
evaporator section. Each
compressor contactor has a side
switch wired in parallel with the
Econ-O-Coil relay and is
responsible for closure of the
low-voltage pump-control circuit.
This low-voltage circuit has a series
of contactors, relays, selector
switch and a flow switch. This
circuit controls the start of the
pumps and provides contact
closure to interlock the
drycooler(s) control circuit. Once
the circuit is closed, 24V is passed
to the pumps control circuit and
the auxiliary relays are energized,
closing the drycooler(s) control
circuit.
Pump P1 is factory set to be the
primary pump (Selector Switch 1-2).
Voltage then passes through the
normally closed contacts of the R2
relay (standby pump relay), through
the current overloads and to the #1
pump contactor. At this point, the
#1 pump and appropriate
drycoolers are running.
When the pump establishes flow, it
opens the system flow switch. The
pump has approximately
10 seconds to establish full flow. If it
does, the system will run in this
state until the call for cooling is
satisfied and the circuit drops out.
If this pump cannot establish flow
or if it has been running and fails,
the flow switch will close and
energize an adjustable relay,
typically set for 10 seconds.
Once this relay times out, it
energizes the R2 switch over relay.
This relay will drop out the voltage
to the #1 pump contactor and
energize the #2 pump contactor.
Along with the R2 relay the AL
relay (alarm relay) will energize.
This will provide a set of closed
contacts for remote indication of
the switch-over situation.
Once the problem with the lead
pump is repaired, the controls must
be reset. To reset the control box,
turn Off the main power to the
control box and then restore the
main power to the control box.
Pump P1 then becomes the
primary pump again.
