Compressors-3 Stages; Compressors-4 Stages; Small Compressors & 1 Large Compressor-5 Stages; Small Compressors & 2 Large Compressors-6 Stages - McQuay MicroTech II Installation And Maintenance Manual

3 Compressors—3 Stages
There are three equally sized compressors and three
independent cooling circuits. The unit capacity is increased
or decreased by turning on and off compressors. One of the
compressors is designated the "Lead" and the other "Lag."
Based on operating hours. When a capacity increase is
required and the cooling capacity is 0%, the "Lead"
compressor is staged on. When further capacity is required, a
"Lag" compressor with the least operating hours of the
remaining two is staged on. When further capacity increase
is required, the remaining "Lag" compressor is staged on.
When a capacity decrease is required, the "Lag" compressor
with the most hours is turned off. When a further capacity
decrease is required, the remaining "Lag" compressor is
turned off. When a further capacity decrease is required, the
"Lead" compressor is staged off.
For detailed information regarding circuit lead/lag operation,
refer to the "Compressor Staging" section of the applicable
operation manual (refer to Table 1 on page 1). Disabled
compressors are not turned on.
Table 16 summarizes the staging sequencing for the
3-Compressor/3-Stage cooling configuration.
Table 16: 3 compressors—3 stages
Stages
1
2
3
4 Compressors—4 Stages
There are four compressors and four independent cooling
circuits. The unit capacity is increased or decreased by
turning compressors on and off. Compressors #1 and #2
provide the first two stages of cooling. The compressor with
the fewest run hours is staged on first and turned off last.
Compressors #3 and #4 provide the last two stages of
cooling. The compressor with the fewest run hours is staged
on first and turned off last. For detailed information
regarding circuit lead/lag operation, refer to the
"Compressor Staging" section of the applicable operation
manual (refer to Table 1 on page 1). Disabled compressors
are not turned on.
Table 17 summarizes the staging sequencing for the
4-Compressor/4-Stage cooling configuration.
Table 17: 4 compressors—4 stages
Stages
1
2
3
4
McQuay IM 710-1
Compressors
1 or 2
1,2 or 1,3 or 2,3
1,2,3
Compressors
1 or 2
1,2
1,2, (3 or 4)
1,2,3,4
3 Small Compressors & 1 Large
Compressor—5 Stages
There are three equally sized small compressors and one
large compressor. Each compressor is on an independent
cooling circuit. The unit capacity is increased or decreased
by staging compressors on and off. Compressors #1 or #2
provide the first stage of cooling. The compressor with the
fewest run hours is staged on first and staged off last.
Compressors 1 and 2 provide the second stage of cooling.
When further capacity is required, an operating small
compressor is turned off and the large compressor is staged
on to provide the third stage of cooling. When further
capacity is required, Compressors #1 or #2 will provide the
fourth stage of cooling. Compressor #3 provides the last
stage of cooling.
Note: Stages 3 and 4 are skipped when the large compressor
is disabled. The next enabled small compressor in the
sequence is staged on when one or more of the small
compressors is disabled and a stage up is required.
Table 18 summarizes the staging sequencing for the 3 Small
Compressors & 1 Large compressor—5-Stage cooling
configuration.
Table 18: 3 Small compressors & 1 large
compressor—5 stages
Stages
1
2
3
4
5
2 Small Compressors & 2 Large
Compressors—6 Stages
There are two equally sized small compressors and two
equally sized large compressors. Each compressor is on an
independent cooling circuit. The unit capacity is increased or
decreased by staging compressors on and off. The small
compressors #1 or #2 provide the first stage of cooling. The
compressor with the fewest run hours is staged on first and
staged off last. The second stage of cooling turns on the
remaining small compressor (#1 or #2). The third stage of
cooling turns off either #1 or #2 and stages on either #3 or
#4. The third stage has one small and one large compressor
operating. The fourth stage of cooling stages on the
remaining small compressor. The fifth stage of cooling turns
off one of the small compressors and stages on the remaining
large compressor. If further cooling is required, the
remaining small compressor is staged on to provide the sixth
stage of cooling. Disabled compressors are ignored. The next
enabled compressor in the sequence is turned on when one or
more compressors are disabled and a stage up is required.
Compressors
1 or 2
1,2
1 or 2,4
1,2,4
1,2,3,4
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