Hooking up a VFD to 3 phase motor, plate says 200v?

TD-4242 · Oct 4, 2018

I'm hooking up a VFD to power a Clausing 1500 lathe with a Doerr 7.5hp motor. I know this machine was powered by standard commercial 3 phase line when I tested it, although I don't know for sure if it was 240v or 480v, assumed 240v. There's no other electronics in the lathe except reversing switches.

I got my VFD and starting going through the numbers and found this 200v a little confusing. Any help deciphering what numbers I need to put into the VFD would be helpful.

It's a 10HP VFD. For reference I included the VFD tag as an additional picture. What kind of tolerance should a motor like this have, if the label was assumed to be right but in the past it was run on standard 208v, 220v or 240v 3 phase is it likely to be ok? Would it be OK to run it at 200v even if it's mislabeled?

Thanks,
-Bill Warner

Tony Quiring · Oct 4, 2018

Likely old motor.

Voltage standards have changed over the years as it was once 115 vac then 120 vac for us split phase.

Current 3 phase common shown as 208 so it could be possible that yesterday's 200 is today's 208.

It is within 10% and your VFD may be able to be tuned.

Contact the manufacturer for their direction as well as others here that may have seen this.

Sent from my SAMSUNG-SM-G930A using Tapatalk

JST · Oct 4, 2018

You should have parameters like "motor rated voltage" and "motor rated frequency". You just set the voltage to 200V, and the frequency to 60 Hz, along with the rated RPM (1740), and current (23 A).

That will set the VFD to produce 200 V when the frequency is the rated frequency (60 Hz)

TD-4242 · Oct 4, 2018

JST said:
You should have parameters like "motor rated voltage" and "motor rated frequency". You just set the voltage to 200V, and the frequency to 60 Hz, along with the rated RPM (1740), and current (23 A).

That will set the VFD to produce 200 V when the frequency is the rated frequency (60 Hz)

I figured I could do that, I guess my questions are:
1) The historical use of this motor was a shop with normal 3 phase service (either 208,240,480 not sure)
2) what effect might this have on the motor?
3) Is it's possible the plate was miss labeled?
4) How would I go about proving the label settings if possible?

Strostkovy · Oct 4, 2018

200V motors are fairly common on 208V supplies.

Jraef · Oct 4, 2018

Strostkovy said:
200V motors are fairly common on 208V supplies.

For every voltage, there are two versions; a Distribution Voltage, and a Utilization Voltage. Distribution is what the utility delivers to you at the Service Drop, Utilization is what the equipment manufacturers build to. The Utilization Voltage is always lower, expecting that there will be voltage drop between the service entrance and the motor terminals. So for 208V Distribution Voltage, motors are designed for 200V. For 240V Dist., Util. is 230V. For 480V Dist., Util. is 460V. In Single Phase, it's 115V for 120V and 230V for 240V again.

110V, 220V and 440V are old standards from before WWII and not valid for new installations but a lot of legacy systems are still that way, they are not forced to change.

Utilization Voltages are designed to be good with +-10%, Distribution Voltages can only vary +-5%. At 3 phase, 5HP and under, most motor mfrs have changed to a motor winding system that is good for 208-230V +-10%. What they do is use a design that is based on 220V +-10%, so it is good for as low as 198V and up to 242V as a compromise, assuming that 208V is mostly used in small commercial installations where the distance from Service to Motor is not likely to cause too much voltage drop. If the motor is designed that way, you will see the nameplate read something like "208/230-460V" and a FLA value that has 3 numbers, one for 208V, one for 230V and one for 460V.

Hope that POS drive works for you... Understand that it is the one that is banned from discussion in this forum (see the "Sticky" thread at the top of the list).

JST · Oct 4, 2018

Dang, you are right..... well I am a nice guy once a year, and the name was not mentioned.

Strostkovy · Oct 5, 2018

Jraef said:
For every voltage, there are two versions; a Distribution Voltage, and a Utilization Voltage. Distribution is what the utility delivers to you at the Service Drop, Utilization is what the equipment manufacturers build to. The Utilization Voltage is always lower, expecting that there will be voltage drop between the service entrance and the motor terminals. So for 208V Distribution Voltage, motors are designed for 200V. For 240V Dist., Util. is 230V. For 480V Dist., Util. is 460V. In Single Phase, it's 115V for 120V and 230V for 240V again.

110V, 220V and 440V are old standards from before WWII and not valid for new installations but a lot of legacy systems are still that way, they are not forced to change.

Utilization Voltages are designed to be good with +-10%, Distribution Voltages can only vary +-5%. At 3 phase, 5HP and under, most motor mfrs have changed to a motor winding system that is good for 208-230V +-10%. What they do is use a design that is based on 220V +-10%, so it is good for as low as 198V and up to 242V as a compromise, assuming that 208V is mostly used in small commercial installations where the distance from Service to Motor is not likely to cause too much voltage drop. If the motor is designed that way, you will see the nameplate read something like "208/230-460V" and a FLA value that has 3 numbers, one for 208V, one for 230V and one for 460V.

Hope that POS drive works for you... Understand that it is the one that is banned from discussion in this forum (see the "Sticky" thread at the top of the list).

Well that was really helpful, thank you.

Seems not to apply always though, unfortunately. Utilization voltage while running a lot of equipment drops down to 200V at the shop. That sounds fine until you find out we have 240V supply. Vast majority of that is prior to our service entry, so we can't do much about it. Don't really want to call the utility company because stuff isn't quite up to code on our end either.

JST · Oct 5, 2018

Unless it is really obvious in your facility, should not be an issue. All they need to see is the service equipment, and maybe a list of loads, they do not do code enforcement.

That sort of drop suggests an undersize transformer that will make itself very obvious sooner or later.

What is the actual no-load voltage? Does it actually drop 40 volts under load?

Strostkovy · Oct 5, 2018

JST said:
Unless it is really obvious in your facility, should not be an issue. All they need to see is the service equipment, and maybe a list of loads, they do not do code enforcement.

That sort of drop suggests an undersize transformer that will make itself very obvious sooner or later.

What is the actual no-load voltage? Does it actually drop 40 volts under load?

No load voltage is 237 at the highest, 232-234 more commonly. We share a transformer with the neighbor, and we are at the very end of the line.

JST · Oct 5, 2018

Ah, well, then.

TD-4242 · Oct 8, 2018

Jraef said:
Hope that POS drive works for you... Understand that it is the one that is banned from discussion in this forum (see the "Sticky" thread at the top of the list).

Thanks for the attention to the sticky I seemed to have missed. I will keep an eye on it closely.

Jraef · Oct 10, 2018

Strostkovy said:
Well that was really helpful, thank you.

Seems not to apply always though, unfortunately. Utilization voltage while running a lot of equipment drops down to 200V at the shop. That sounds fine until you find out we have 240V supply. Vast majority of that is prior to our service entry, so we can't do much about it. Don't really want to call the utility company because stuff isn't quite up to code on our end either.

As JST said, that's actually a problem to have that much VD from your service. But in this case you are in luck, because your motor will be just fine with it! program your VFD to output 200V at 60Hz. From the VFD's standpoint, so long as the input is above 200V, you are fine, it won't care one bit when it climbs to 234V, it will still only give the motor 200V at full speed.

Strostkovy · Oct 10, 2018

Jraef said:
As JST said, that's actually a problem to have that much VD from your service. But in this case you are in luck, because your motor will be just fine with it! program your VFD to output 200V at 60Hz. From the VFD's standpoint, so long as the input is above 200V, you are fine, it won't care one bit when it climbs to 234V, it will still only give the motor 200V at full speed.

The equipment that draws that much power is either a stackup of single phase stuff and little three phase (plasma table, air compressor, press brake, welders) or one large three phase load powered by a 50hp RPC. Everything has 208V tolerant motors, and does not run at full load, so I should be okay from a motor standpoint. I don't have any VFDs in my shop personally.

That's a good point on the VFD though, because at some point I will probably get a three phase lathe that is a good distance from the RPC and would like to use a VFD on it. I'll be sure to get one set up for 208 and set the VFD accordingly.

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