Evaporator Pump Start Contacts; System Run Contacts; Alarm Status Contacts; Remote Start/Stop Contacts - York YCAL0019 Installation, Operation And Maintenance Manual

SECTION 4 – INSTALLATION
acteristics that may cause loose terminations result-
ing from the contraction and expansion of the wiring.
Aluminum oxide may also build up at the termination
causing hot spots and eventual failure. If aluminum
wiring is used to supply power to the chiller, AL-CU
compression fittings should be used to transition from
aluminum to copper. This transition should be done in
an external box separate to the power panel. Copper
conductors can then be run from the box to the chiller.
A 120-1-60, 15 amp source must be supplied for the
control panel through a fused disconnect when a con-
trol panel transformer (optional) is not provided (Refer
to Figure 10).
See unit wiring diagrams for field and power wiring
connections, chilled water pump starter contacts, alarm
contacts, compressor run status contacts, PWM input,
and load limit input. Refer to Section 8 "Unit Opera-
tion" for a detailed description of operation concerning
aforementioned contacts and inputs.

Evaporator Pump Start Contacts

Terminal block TB1 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 pow-
ered up for less than 30 seconds, or if the pump has run
in the last 30 seconds, to prevent pump motor over-
heating. Refer to Figure 11 and unit wiring dia gram.

System Run Contacts

Contacts are available to monitor system status. Nor-
mally-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 sys-
tem 2 (YCAL0043 to YCAL0066). Refer to Figure 5,
11 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 respec-
tive contacts will open when the unit is shut down on a
unit fault, or locked out on a system fault. Field connec-
tions are at TB1 terminals 29 to 30 (system 1), and ter-
minals 31 to 32 (system 2 YCAL0043 to YCAL0066).
42

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 Figure 5, 11 and unit wir-
ing 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 re-
moved if emergency shutdown contacts are installed.
Refer to Figure 11 and unit wiring diagram.

Remote Temp Reset Input

The Remote Temp Reset input allows reset of the
chilled liquid set point by supplying a voltage or cur-
rent signal field wiring should be connected to CTB1
terminals A+ to A-. A detailed explanation is provided
in the Unit Control section. Refer to Figure's. 3 and 5
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%, depend-
ing on the number of compressors on unit. The field
connections are wired to CTB1 terminals 13 to 21, and
work in conjunction with the PWM inputs. A detailed
explanation is provided in the Unit Control section.
Refer to Figure 5, 11 and unit wiring diagram.
When using the Load Limit feature,
the PWM feature will not function
– SIMULTANEOUS 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 Figure 4 and the unit wiring diagram.
FORM 150.67-NM1
ISSUE DATE: 4/28/2017
JOHNSON CONTROLS