Compressor motor for Centrifugal Chiller

[ksm]

Dear All,

I'd like to know how to calculate the time to get motor full speed during compressor motor starting for Centrifugal Chiller? Is it can calculate?

That period of time is depends on load or starter? Or depends on other factors?

Anyone can helps to advice? Thanks.

[goshen]

Dear All,

I'd like to know how to calculate the time to get motor full speed during compressor motor starting for Centrifugal Chiller? Is it can calculate?

That period of time is depends on load or starter? Or depends on other factors?

Anyone can helps to advice? Thanks.

Hi:
if you are running a 2 pole motor at 50 hz ,then the motor will turn at approx 3000 rpm, as soon as it transitions from star to delta, if this is your method of starting.
if you are using a soft starter, then full speed time is set on the starter .
when using a vsd, you can monitor and precisley set the time to reach full speed.
usually these machines start unloaded ,so reaching the running speed is not load dependent.

[BekTek]

What starting method and what type of chiller.
Gear drive single stage chillers will ramp up a bit quicker due to the small rotating mass of the impeller.
Staged chillers with two or more large wheels on the motor shaft will take a bit more time.
It also depends on the starting conditions of the chilled water temperature and condenser temps to a small degree.
In old starters with a transition timer, the timer was set for 22 seconds to force transition. In newer solid state motor control systems, as soon as the amperage drops after a wye start it would transition to delta. Anywhere from 3 to 10 seconds or there abouts.
If you are using a solid state starter and are looking for a ramp time, consult with the starter manufacturer and they will have a suggested time to bring the motor up to speed.

[ksm]

Thanks a lot Goshen.

[ksm]

Thanks BekTek.