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Installation
Removing high voltage power to
the chiller will remove the 115VAC
supply voltage to the microprocessor
circuitry and the evaporator heater. In
cold weather, this could cause serious
damage to the chiller due to evaporator
freeze‑up. Do not remove power unless
alternate means are taken to assure
operation of the evaporator heater.
Remote Emergency Stop Device
If required, a remote emergency stop device can be wired
into the unit. The device should be wired into terminals
31 and 32 (Figs. 12 and 13, pages 39 and 40). in the
microprocessor control panel.
CONTROL PANEL WIRING
All wiring to the control panel terminal block is nomi-
nal 30VDC and must be run in shielded cable, with the
shield grounded at the panel end only. Run shielded
cable separately from mains cable to avoid electrical
noise pick-up. Use the control panel cable entry to avoid
the power cables.
The voltage free contacts must be suitable for 30VDC
(gold contacts recommended). If the voltage free con-
tacts form part of a relay or contactor, the coil of the
device must be suppressed using a standard R/C sup-
pressor. The above precautions must be taken to avoid
electrical noise which could cause a malfunction or
damage to the unit and its controls.
The length of cable to these terminals must not exceed
25 ft. (7.5 m) unless an optional input isolator kit is
fitted. The optional input isolator kit uses 15VDC (not
30VDC).
VOLTS FREE CONTACTS
Chilled Liquid Pump Starter
Terminals 25 and 26 (Figs. 12 and 13, pages 39 and 40)
close to start the chilled liquid pump. This contact can be
used as a master start/stop for the pump in conjunction
with the daily start/stop schedule.
JOHNSON CONTROLS
Run Contact
Terminals 29 and 30 (Figs. 12 and 13, pages 39 and 40)
close to indicate that a system is running.
Alarm Contacts
Each system has a voltage-free change over contact
which will operate to signal an alarm condition whenever
a system locks out, or there is a power failure. To obtain
system alarm signal, connect the alarm circuit to volt
free terminals 23 and 24 (Figs. 12 and 13, pages 39 and
40) for No. 1 System and to terminals 27 and 28 (Figs.
12 and 13, pages 39 and 40) for No. 2 System.
SYSTEM INPUTS
Flow Switch
A chilled liquid flow switch of suitable type must be
connected to terminals 13 and 14 (Figs. 12 and 13, pages
39 and 40) to provide adequate protection against loss
of liquid flow.
Remote Run / Stop
Connect remote switch(es) in series with the flow switch
to provide remote run/stop control if required.
Remote Print
Closure of suitable contacts connected to terminals 13
and 18 (Figs. 12 and 13, pages 39 and 40) will cause a
hard copy printout of Operating Data/Fault History to
be made if an optional printer is connected to the RS
232 port.
Remote Setpoint Offset – Temperature
Timed closure of suitable contacts connected to
terminals 13 and 17 (PWM contacts) will provide
remote offset function of the chilled liquid set point
if required. See Figs. 12 and 13, pages 39 and 40 for
contact location.
Remote Setpoint Offset – Current
Timed contact closure of a suitable contact connected
to terminals 13 and 16 (PWM contacts) will provide
remote offset of EMS% CURRENT LOAD LIMIT. See
Figs. 12 and 13, pages 39 and 40 for contact location.
FORM 201.18-NM7
35
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