York MILLENNIUM YCAS Installation Operation & Maintenance page 34

Installation
The voltage free contacts must be suitable for 30 VDC
(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 dam-
age to the unit and its controls.
The length of cable to these terminals must not exceed
7.5 m (25 ft.) unless an optional input isolator kit is fit-
ted. The optional input isolator kit uses 15 VDC (not 30
VDC).
VOLTS FREE CONTACTS
Chilled Liquid Pump Starter
Terminals 25 and 26 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.
If no schedule is set, and the customer has master con-
trol of the pump, the contact must be used to override
the customer master start/stop so that the YORK con-
tact can start the pump in the event of a low tempera-
ture liquid condition.
Run Contact
Terminals 29 and 30 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 when-
34
ever 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 for No. 1 System and to
terminals 27 and 28 for No.2 System.
SYSTEM INPUTS
Flow Switch
A chilled liquid flow switch of suitable type must be
connected to terminals 13 and 14 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 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 Set Point Offset - Temperature
Timed closure of suitable contacts connected to termi-
nals 13 and 17 (PWM contacts) will give remote offset
function of the chilled liquid set point if required.
Remote Set Point Offset - Current
Timed contact closure of a suitable contact connected
to terminals 13 and 16 (PWM contacts) will give re-
mote offset of EMS% CURRENT LOAD LIMIT.
YORK INTERNATIONAL