York MILLENNIUM YCAL0043SC, Manual, Page: 12 / 133

YORK INTERNATIONAL
12
EVAPORATOR PUMP START CONTACTS
Terminal block CTB2 - terminals 23 to 24, are normally
open contacts that can be used to switch field supplied
power to provide a start signal to the evaporator pump
contactor. The contacts will be closed when any of the
following conditions occur:
1. Low Leaving Chilled Liquid Fault
2. Any compressor is running.
3. Daily schedule is not programmed OFF and the Unit
Switch is ON.
The pump will not run if the micropanel has been pow-
ered up for less than 30 seconds, or if the pump has run
in the last 30 seconds, to prevent pump motor overheat-
ing. Refer to Figure 5 and unit wiring diagram.
SYSTEM RUN CONTACTS
Contacts are available to monitor system status.
Normally-open auxiliary contacts from each compressor
contactor are wired in paralleled with CTB2 - terminals
25 to 26 for system 1, and CTB2 - terminals 27 to 28 for
system 2 (YCAL0040 - YCAL0080). Refer to Figure 5
and unit wiring diagram.
ALARM STATUS CONTACTS
Normally-open contacts are available for each refrigerant
system. These normally-open contacts close when the
system if functionally normally. The respective contacts
will open when the unit is shut down on a unit fault, or
locked out on a system fault. Field connections are at
CTB2 terminals 29 to 30 (system 1), and terminals 31 to
32 (system 2 YCAL0117 - YCAL0253).
REMOTE START/STOP CONTACTS
To remotely start and stop the chiller, dry contacts can
be wired in series with the flow switch and CTB2 - termi-
nals 13 to 14. Refer to figure 5 and unit wiring diagram.
REMOTE EMERGENCY CUTOFF
Immediate shutdown of the chiller can be accomplished
by opening a field installed dry contact to break the elec-
trical circuit between terminals 5 to L on terminal block
CTB2. The unit is shipped with a factory jumper installed
between terminals 5 to L, which must be removed if emer-
gency shutdown contacts are installed. Refer to Figure 5
and unit wiring diagram.
PWM INPUT
The PWIVI input allows reset of the chilled liquid setpoint
by supplying a “timed” contact closure. Field wiring
should be connected to CTB1 - terminals 13 to 20. A
detailed explanation is provided in the Unit Control sec-
tion. Refer to Figure 5 and unit wiring diagram.
LOAD LIMIT INPUT
Load limiting is a feature that prevents the unit from load-
ing beyond a desired value. The unit can be “load limited”
either 33%, 50%, or 66%, depending on the number of
compressors on unit. The field connections are wired to
CTB1 - terminals 13 to 21, and work in conjunction with
the PWIVI inputs. A detailed explanation is provided in
the Unit Control section. Refer to Figure 5 and unit wiring
diagram.
When using the Load Limit feature, the
PWM feature will not function - SIMUL-
TANEOUS OPERATION OF LOAD
LIMITING AND TEMPERATURE RE-
SET (PWM INPUT) CANNOT BE
DONE.
FLOW SWITCH INPUT
The flow switch is field wired to CTB1 terminals 13 - 14.
See Figure 5 and unit wiring diagram.
Installation