Johnson Controls YORK Tempo YLAA Series, Installation Operation & Maintenance

Page: 43 / 192

FORM 150.72-NM1 (1020)
43
JOHNSON CONTROLS
4
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
XTBC2 - Terminals 29 to 30 (system 1), and Terminals
31 to 32 (system 2).
Remote Start/Stop Contacts
To remotely start and stop the chiller, dry contacts can
be wired across terminals 13 and 51 on XTBC1. Refer
to Fig 4, 10 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
electrical circuit between Terminals 5 to L on Terminal
Block XTBC2. 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. 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 current signal
field wiring should be connected to XTBC1 – Terminals
A+ to A-. A detailed explanation is provided in the Unit
Control section. Refer to Fig’s. 3, 4 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 XTBC1 – Terminals 13
to 21, and work in conjunction with the PWM inputs.
A detailed explanation is provided in the Unit Control
section. Refer to Fig. 4, 10 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 XTBC1 Terminals 13
- 14. See Fig. 4 and unit wiring diagram.
COMPRESSOR HEATERS
Compressor heaters are standard. ZP103, ZP120
and ZP137 compressors utilize 90W heaters; ZP180
compressors utilize 70W heaters; ZP235 compressors
utilize 120W heaters. 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.
RELIEF VALVES
Relief valves are located on both the high and low
pressure side of the piping. High side relief valve
pressure setting is 650 PSIG. Low side relief valve
pressure setting is 450 PSIG.
HIGH PRESSURE CUTOUT
A high pressure cutout is installed in the discharge piping
of each system. The cutout opens at 585 PSIG ± 10
PSIG and closes at 440 PSIG ± 25 PSIG.