# Acs 550



## JRaef (Mar 23, 2009)

Officially, the only mention of using an ACS550 on a single phase input is for 240V drives, in which they say it can be done with a 50% de-rate of the drive. There is no mention of being able to do that on a 480V drive.

However, I have done it, it works. You still need the 50% de-rate however, and don't fudge on that. The reason is, the ACS550 doesn't have input phase loss protection directly, but indirectly it is monitoring the DC bus ripple. When you feed the drive with single phase, the DC bus ripple increases and will trigger that protection, Fault 22, called "Supply Phase". You can compensate for the added ripple by adding capacitance, which is one reason for the 50% de-rate. The other reason is that the current through he rectifier diodes increase by a factor of 1.732 (the sq. rt. of 3). But with the 50% de-rate, you are covering this issue as well. People however often make the mistake of thinking only of the 1.732X factor and get cheap to avoid having to buy the next size up if they can, but that sets up nuisance tripping on excess DC bus ripple.

Word to the wise though, if anything goes wrong with the drive while under warranty, don't tell them it's being used on single phase input, because you give them justification for saying it's not covered since they never officially say it can be done. 

I won't cover your warranty either :whistling2:


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## Glen Walker (Dec 30, 2009)

Im afraid this is the route Im going to have to take to get this one done. If I had my way though I would love to use a Bonitron Power Supply and a Powerflex 525. Unfortunately I think the price differential is enough to keep my customer from letting us go with that option. If Bonitron offered something in the 15 hp range it would help also.


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