Issue:
Why is the demand limit setpoint set to 200%?
Resolution:
demand limit setpoint set to 200%
Demand limit on RTAE is different than current limit on previous products. It looks at the total chiller power consumption of the chiller, including the predicted power consumption of the fans, and then reduces the speed of the compressor to achieve that power consumption. The reason the demand limit setpoint is set higher than 100% (when demand limit is not needed by the customer) is to ensure that it is out of the way. Setting it to 100% would be fine if the chiller is running at ARI conditions, but if the outdoor air temp is greater than ARI conditions, than the compressor will need to draw more power to achieve design tons. In that case, setting demand limit at 100% would limit the compressors capacity. There are still other limits in place to protect the chiller including current limits to protect the motor, condenser pressure limits, etc.
Notes:
Changes:
Other Question/Problem/Cause Statements:
- Why is the demand limit setpoint set to 200%?
- What is demand limit for RTAE chillers?
Facts:
- Air-Cooled Chiller (Pueblo) (RTAE)
Document Identifier: DOC-108083
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.