Johnson Controls YORK Tempo YLAA Series, Установка, эксплуатация и обслуживание

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FORM 150.72-NM1 (1020)
163
JOHNSON CONTROLS
8
LOAD LIMITING
Load Limiting is a feature that prevents the unit from
loading beyond the desired value. 2 and 4 compressor
units can be load limited to 50%. This would allow only
1 compressor per system to run. 3 and 6 compressor units
can be load limited to 33% or 66%. The 66% limit would
allow up to 2 compressors per system to run, and the
33% limit would allow only 1 compressor per system
to run. Five-compressor units may be load limited to
40% (1 compressor per system runs) or 80% (up to 2
compressors per system) are permitted to run. No other
values of limiting are available.
There are two ways to load limit the unit. The first is
through remote communication via an ISN. Load limit
stages are sent through YORK Talk on pages 9 and 10
of feature 54. Page 9 is stage 1 load limit and page 10
is stage 2 load limit.
A second stage of load limiting the unit is accomplished
by closing contacts connected to the Load Limit
(XTBC1 – terminals 13-21) and PWM inputs (XTBC1
– terminals 13-20). Stage 1 of load limiting involves
closing the Load Limit input. Stage 2 of load limiting
involves closing both the Load Limit and PWM inputs.
The first stage of limiting is either 80%, 66% or 50%,
depending on the number of compressors on the unit.
The second stage of limiting is either 40% or 33% and
is only available on 3, 5 and 6 compressor units. Table
19 shows the load limiting permitted for the various
numbers of compressors.
Simultaneous operation of Remote
Load Limiting and EMS­PWM Tem -
perature Reset (described on following
pages) cannot occur.
COMPRESSOR RUN STATUS
Compressor run status is indicated by closure of contacts
at XTBC2 – terminals 25 to 26 for system 1 and XTBC2
– terminals 27 to 28 for system 2.
ALARM STATUS
System or unit shutdown is indicated by normally-open
alarm contacts opening whenever the unit shuts down on
a unit fault, locks out on a system fault, or experiences
a loss of power to the chiller electronics . System 1
alarm contacts are located at XTBC2 – terminals 29 to
30. System 2 alarm contacts are located at XTBC2 –
terminals 31 to 32. The alarm contacts will close when
conditions allow the unit to operate, or the fault is reset
during a loss of power, the contacts will remain open
until power is reapplied and no fault conditions exist.
COMPRESSORS
IN UNIT
STAGE 1 STAGE 2
2 50% -
3 66% 33%
4 50% -
5 80% 40%
6 66% 33%
TABLE 19 – COMPRESSOR OPERATION –
LOAD LIMITING