variable speed primary chilled water system 1

[dk2499]

What is the best control strategy for not going beyond a chillers maximum rate of flow change, while still controlling the VFD's based off of zone differential pressure. IE if the controller sees a sudden drop in zone dp, it will increase the drive speed to compensate. In doing so, you could exceed the recommended 10% per minute change in flow rate.

 

[quark]

The recommended maximum % change in flowrate generally corresponds to a temperature control with a precision of +/-0.5⁰C and it depends upon how tight a control you require. However, you can have your VSD run with a set ramp up rate to match the recommended maximum change.

This is for a variable primary flow application. If you have only secondary variable flows, this doesn't matter at all.