York YCAL0014E Series, Установка, эксплуатация и обслуживание

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JOHNSON CONTROLS
123
FORM 150.62-NM8 (1020)
3
LOAD LIMITING
Load limiting is a feature that prevents the unit from
loading beyond the desired value. Two and four
compressor units can be load limited to 50%. This would
allow only 1 compressor per system to run. Three and six
compressor units can be load limited to 33% or 66%. The
66% limit would allow up to two 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 two 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.
A second way to load limit the unit is through closing
contacts connected to the Load Limit (CTB1 – terminals
13 and 21) and PWM inputs (CTB1 – terminals 13 and
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 three, five & six compressor units. Table 32 shows
the load limiting permitted for the various number of
compressors.
Simultaneous operation of load limit -
ing and EMS-PWM Temperature Reset
(described on following pages) cannot
occur.
COMPRESSOR RUN STATUS
Compressor run status is indicated by closure of contacts
at CTB2 – terminals 25 to 26 for system 1 and CTB2 –
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, or locks out on a system fault. System 1
alarm contacts are located at CTB2 – terminals 29 to 30.
System 2 alarm contacts are located at CTB2 – terminals
31 to 32. The alarm contacts will close when conditions
allow the unit to operate.
TABLE 32 – COMPRESSOR OPERATION – LOAD LIMITING
COMPRESSORS IN UNIT STAGE 1 STAGE 2
2 50% –
3 66% 33%
4 50% –
5 80% 40%
6 66% 33%