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Removing high voltage power to the
chill er will re move the 115VAC sup-
ply voltage to the mi cro pro ces sor cir-
cuit ry and the evap o ra tor heater. In
cold weath er, this could cause serious
dam age to the chill er due to evap o ra tor
freeze-up. Do not re move power un less
alternate means are taken to as sure
op er a tion of the evap o ra tor heat er.
Remote Emergency Stop Device
If required, a remote emergency stop de vice can be wired
into the unit. The device should be wired into ter mi nals
31 and 32 (Figs. 13 and 14, pages 38 and 39) in the
mi cro pro ces sor con trol pan el.
CONTROL PANEL WIRING
All wiring to the control panel terminal block terminals
13-19 is nom i nal 30VDC and must be run in shielded
cable, with the shield grounded at the panel end only.
Run shielded ca ble sep a rate ly from mains cables to
avoid electrical noise pick-up. Use the control panel
cable entry to avoid the pow er cables.
The voltage free contacts must be suitable for 30VDC
(gold contacts recommended). If the voltage free con-
tacts are from a relay or contactor, the coil of the device
must be suppressed using a standard R/C sup pres sor.
The above precautions must be taken to avoid electrical
noise which could cause a malfunction or dam age to the
unit and its controls.
The length of cable to these terminals must not exceed
25 ft. (7.5 m) unless an isolator is fi t ted.
VOLTS FREE CONTACTS
Chilled Liquid Pump Starter
Terminals 25 and 26 (Figs. 13 and 14, pages 38 and 39)
close to start the chilled liquid pump. This contact can be
used as a master start/stop for the pump in con junc tion
with the daily start/stop schedule. See Section 8.1.15.
Run Contact
Terminals 29 and 30 (Figs. 13 and 14, pages 38 and 39)
close to in di cate that a sys tem is running.
YORK INTERNATIONAL
Alarm Contacts
Each system has a voltage-free change over contact
which will operate to signal an alarm condition when-
ev er 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. 13 and 14, pages 38
and 39) for No. 1 Sys tem, ter mi nals 27 and 28 for No.
2 Sys tem, terminals 37 and 38 for No. 3 System and
terminals 41 and 42 for No. 4 System.
SYSTEM INPUTS
Flow Switch
A chilled water fl ow switch, (either by YORK or others)
MUST be installed in the leaving water piping of the
evaporator. There should be a straight horizontal run of
at least 5 diameters on each side of the switch. Adjust
the fl ow switch paddle to the minimum fl ow allowed
through the evaporator. (See manufacturer's instructions
furnished with the switch.) The switch is to be wired to
terminals 13 - 14 of CTB1 located in the control panel,
as shown on the unit wiring diagram.
Remote Run / Stop
Connect remote switch(es) in series with the fl ow switch
to provide remote run/stop control if required.
Remote Print
Closure of suitable contacts connected to terminals 13
and 18 (Figs. 13 and 14, pages 38 and 39) will cause a
hard copy printout of Operating Data/Fault History to
be made if an optional printer is con nect ed to the RS
232 port.
Remote Setpoint Offset – Temperature
Timed closure of suitable contacts connected to
ter mi nals 13 and 17 (PWM contacts) will provide
re mote off set function of the chilled liquid set point
if re quired. See Figs. 13 and 14, pages 38 and 39 for
contact lo ca tion.
Remote Setpoint Offset – Current
Timed contact closure of a suitable contact connected to
terminals 13 and 16 (PWM contacts) will provide re mote
offset of EMS% CURRENT LOAD LIMIT. See Figs.
13 and 14, pages 38 and 39 for contact lo ca tion.
FORM 201.19-NM6 (804)
4
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