230v to 400v - with supply of 208v 3ph

[Big_Chief]

Got an electrical question... looking for reassurance or insights.

Setting up a CNC Bender. The machine has a transformer on it that lists 230v input 3ph. The transformer then boosts to 400v to run the machine. My supply voltage is 208v. My electrician says I will be fine without any buck/boosters. While I have used this electrician for years... and dont want to question them, I figured I would open this up to strangers for insights.

I know the general rule of +/- 10%... but I have only heard this when you hooking directly to a motor. Since this setup is going to a transformer first, does the same rule still apply? Also, the motor on this machine is a servo motor (German machine) and not sure if makes a difference since it does not run constant. better, worse, no difference?

I should mention... I have other equipment rated at 220v running on this 208v without any problems. But these are wired direct to the motors (standard, not servo motors).

Thanks for any insights,

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[Jim Dawson]

Many times the German machines have several taps on the 230/400 transformer. I would look for a 220 or 210 V tap. If that doesn't exist, then you should be fine anyway because most of the servo drives are 380V nominal, with an allowance to go above 400 a bit. I used to be a field tech for a German company and it was the late 90's that I saw the voltages being marked 400V rather than 380V.

About the worst case is that the servo motor won't quite turn at it's max rated speed, that should not be a problem. It might take a fraction of a second longer to make the bend.