[ka67_72]

I am converting a Bridgeport Series I. I currently have 5 AMC B25a40E amps and four 320vdc brushless servos. Two are 1888oz-in, and two are 340oz-in. I need one more servo and a controller(s). My amps will run 120-400vdc.

In a servo, what is the advantage of volts over current? The wattage is the same, right? I'm trying to decide whether I should run 120, 240, or step it up to 320.

Should the big servos be enough to drive my x, y, or z without gearing them down? Will one of the smaller ones be able to drive my y or z axis at all or should I just save them for the rotary tables?

Thanks,
Kevin

[unterhaus]

I didn't think that any AMC drives would go that high? I didn't see your exact drive on their site. But having 120 or 240 as an input voltage suggests that it is one of the AC input drives. For those, it doesn't matter if you use either, the servomotor is going to see the same voltage. I'm pretty sure AMC doesn't make any drives that go to 320.

The advantage of higher voltage for a given motor is the max speed is proportional to voltage. If it is a dc input drive, I'd probably get an isolation transformer and run rectified 120v into the drive.

You need to check your ratings.

[Al_The_Man]

My AMC catalogue shows BLDC drives up to 400vdc, The closest I can find is the B30A40, which is max 30amp and 400dc.
I think the AMC technical site states that the DC power supply voltage can be 110% ~ 150% of max motor voltage rating.
Al.

[unterhaus]

Sorry I didn't look harder for the data sheets, I need new glasses and by friday my eyes are killing me.

hard to know what power devices they use because they have little elves sand the part numbers off of all the chips, so it's a little difficult to assess how high you can actually run the drives. I start getting a little paranoid above 200vdc, particularly if I built the power supply. So if it was me, if I didn't need the speed that 320v will give, I would stop at rectified 120vac, which is 170vdc or thereabouts. Rectified 240vac will give you your 320v. Often, using 220v instead of 120v will cut the amperage in half. That's not clear in this case, depends on loads and speeds.

[ka67_72]

Thanks for the info guys. I'll start by rectifying 120 and see how it goes. If I need more I'll go for 220.

Thanks,
Kevin