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Chiller voltage selection

Chiller voltage selection

Can someone please give some pros and cons of selecting 4160 volt versus 480 volt power for centrifugal chillers.  This would be a new plant with three 1900 ton for HVAC and two 1100 ton for process.  Thanks in advance.

RE: Chiller voltage selection

I'm no electrician, but my estimate for the 480 volt amperage on the larger units is 1500 - 2000 amps.  Those are some pretty large conductors, contactors, conduits, etc.

From an efficiency standpoint, every step of voltage reduction will result in some loss in the transformer.  So a higher voltage motor should cost less to operate (you'll need input from an EE to quantify).  Also, the cost of additional switchgear should be looked at for the two cases.

RE: Chiller voltage selection

Here in south east asia, 1000TR and above chillers are generally run on 3.3 KV power supply. One main reason being economy in sizing the transformers to step down from incoming power supply of 22 KV to 3.3 KV. It also helps in economical cable sizing , routing and motor control centre design. A chiller 100TR above (operating on low voltage) may require a soft start in order not to upset the electrical system every time the chiller starts.There is a cost implications in terms of starters for chillers, electrical room to house medium voltage switch gear etc.


RE: Chiller voltage selection


The above two posters have it about right.  For economy, it's good to pay attention to what the contactor manufacturers list as "standard" products though.  At 1900 tons, you'll be looking at 1500+ amps, and standard motor starters don't go above 600 or 800 that I've seen.  

At 4160 volts, you're down to 200 or less, but a hint here is that when you cross the 3300 volt mark, you're beginning to pay more of a premium for your contactor.  Again, it's a line that the manufacturers have drawn due to UL differences, etc..., that makes the difference.

If you can get a 3300-volt motor, or even a 2400-volt, you should be in the "best economy" range for this size machine.

Let us know how it turns out!

Old Dave

RE: Chiller voltage selection



RE: Chiller voltage selection

I have seen that high voltages ( more than 600v)are the limit to a lot of NEC regulations, so you must invest in comply with them. For 4160v Special insulated cable is required with special connections and test. The feeders , dissconects ,ect also need to have extremly high arc prevension.
 Also, non-standard motors on chillers will cost you more generally. Because you require a special starter. Although it may be X-L it will need all this safety features for the high voltage.
 When I asked a few of my pharmaceutical collegues why would they preferr a 4160v chiller the most intelligent answer was to separate the big motor from the small ones to dont afect one each other distribution lines when starting and stopping. Preventing mayor probloens in the event of brown outs.
But in this day whith regulated power I dont see the need.

RE: Chiller voltage selection

Hi !  If you already have a 480 v electrical system in place, you might want to keep/use it. If you ever want to consider a variable speed drive in the future for energy savings, there are standard drives available from the chiller manufacturers and others. A higher voltage VSD is available from very few suppliers. The use of VSD's should be considered. They generally are very cost effective.

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