Page 34 OM 780-2
Chiller Sequencing Control
As the cooling load varies, the CSM enables and disables chillers so that the current cooling capacity is matched to the
current cooling load. This action is commonly called chiller sequencing. The two fundamental elements of any sequencing
control strategy are the sequence order, the order in which chillers are enabled and disabled, and the sequencing logic, the
rules by which chillers are enabled and disabled to match the cooling capacity to the load.
To view the current status of chiller sequencing, go to the System Status screen. To configure chiller sequencing, go to the
Chiller Seq screen to change the values described in Table 9 and Table 10.
Sequencing and Staging
In the CSM, a chiller stage is defined as a set of chillers. As the CSM sequences chillers on and off, it “stages up” and
“stages down.” If the sequence order is set properly, each successive stage has more capacity than the preceding stage.
Additional capacity could be in the form of one added chiller (typical), or a chiller swap (in which the replacement chiller
has more capacity than the one that is stopped). Thus the words “sequencing” and “staging” essentially mean the same
thing.
Sequence Order
Figure 10. Chiller Sequence Order Table (Main > Configuration > Chiller Seq)
Table 9. Chiller Seq - Chiller Sequencing Order (Main > Configuration > Chiller Seq)
Name Description
Sequence
Number
This input sets the order of chiller staging within a row. All chillers with the same Sequence Number form a group of chillers
from which the CSM automatically sequences based on run time. If all chillers have unique Sequence Numbers a fixed
sequencing order results. A chiller with Sequence Number = 0 is considered not in the row and will remain disabled. Chiller
sequence numbering starts over at 1 each time you switch to a higher row. Range = 0 – Number Of Chillers. Default = 0 (for all
chillers in all rows)
Staging Mode This input assigns the chiller to be sequenced normally or as a standby chiller. Each standby chiller must have a Sequence
Number greater than or equal to all non-standby chillers for which it is in standby. If a chiller is designated as Standby, the CSM
To Next Page
Loading...
Need help?
General
