York YCAL0014E Series, Installation Operation & Maintenance

Page: 22 / 212

JOHNSON CONTROLS
22
FORM 150.62-NM8 (1020)
INSTALLATION
Evaporator Pump Start Contacts
Terminal block CTB2 – terminals 23 to 24, are nor mally-
open contacts that can be used to switch field supplied
power to provide a start signal to the evapo rator 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 micro panel has been
powered up for less than 30 seconds, or if the pump
has run in the last 30 seconds, to prevent pump motor
overheating. Refer to Fig. 6 and unit wiring dia gram.
System Run Contacts
Contacts are available to monitor system status.
Normally-open auxiliary contacts from each com pressor
contactor are wired in parallel with TB1 – terminals 25
to 26 for system 1, and TB1 – termi nals 27 to 28 for
system 2 (YCAL0040 - YCAL0134). Refer to Fig. 6
and unit wiring diagram.
Alarm Status Contacts
Normally-open contacts are available for each re-
frigerant system. These normally-open contacts close
when the system is functioning 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 TB1 terminals 29 to 30 (system 1), and terminals
31 to 32 (system 2 YCAL0040 - YCAL0134).
Remote Start/Stop Contacts
To remotely start and stop the chiller, dry contacts can be
wired in series with the flow switch and CTB1 ‑ termi‑
nals 13 to 14. Refer to Fig. 6 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
TB1. The unit is shipped with a factory jumper installed
between terminals 5 to L, which must be removed if
emergency shutdown contacts are installed. Refer to
Fig. 6 and unit wiring diagram.
PWM Input
The PWM input allows reset of the chilled liquid set-
point by supplying a “timed” contact closure. Field
wiring should be connected to TB1 – terminals 13 to 20.
A detailed explanation is provided in Section 2, “Unit
Controls”.
Refer to Fig. 6 and unit wiring diagram.
Load Limit Input
Load limiting is a feature that prevents the unit from
loading beyond a desired value. The unit can be “load
limited” either 33%, 40%, 50%, 66% or 80%, depending
on the number of compressors on unit. The field
connections are wired to TB1 – terminals 13 to 21, and
work in conjunction with the PWM inputs. A detailed
explanation is provided in Section 2, “Unit Controls”.
Refer to Fig. 6 and unit wiring diagram.
When using the Load Limit feature,
the PWM feature will not function. Si -
multaneous operation of load limiting
and tem perature reset (PWM input)
cannot be done.
Flow Switch Input
The flow switch is field wired to CTB1 terminals 13 and
14. See Fig. 6 and unit wiring diagram.
Compressor Heaters
Compressor heaters are standard. If power is OFF more
than two hours, the crankcase heaters must be energized
for 18 - 24 hours prior to restarting a compressor. This
will assure that liquid slugging and oil dilution does not
damage the compressors on start.