Motors Question -- title edited by Phil

[bulletin blues]

Could the O.P. please explain why Australian motors are easier to connect than American motors? I've never had the opportunity to wire one.
Thanx

 

[Tharon]

Could the O.P. please explain why Australian motors are easier to connect than American motors? I've never had the opportunity to wire one.
Thanx

I don't know... all the motors on our machines from Germany have high/low voltage configurations. I figured it was very common world wide. (NEC and IEC)

 

[504bloke]

Could the O.P. please explain why Australian motors are easier to connect than American motors? I've never had the opportunity to wire one.
Thanx

I would guess the 9 wires have him confused, most european motors have 6 wires.

 

[504bloke]

Hey all,

I'm very embarrassed to ask this question but I truely dont know the answer.

The machine was imported from the states 2nd hand (in great condition mind) and has a number of like motors that currently are all configured for high voltage.

The one i'll pick on is a 9 wire 7.5kW (10hp) motor that is internally star (wye) connected. The name plate voltage is 230/460V. It is to be hooked up to a Eurotherm 690 VSD.

Our system in Australia is 240/415V. Where the secondary of the utility supply transformer is star (wye) orientated. 415V phase to phase and 230V phase to nuetral.

I'm guessing that I will re-work the motors in the low voltage configuration. This will have a like pair of windings in parallel per phase with 240V dropped across them.

Is this the correct way to wire this motor?

Second side question, the motors are all wired in high voltage, so does that mean that there was 460V dropped across the 2 series windings. Go by root3 thats a line voltage of almost 800V???
Sorry to have to ask, but you yanks got me second guessing myself!

Can you post a picture of the motor nameplate ?

 

[ArikBY]

First I must say I understand the OP.American motors are hard to understand.For us any how.
European motors are easy to understand.
The language he use is impolite.I think he understand that and apologized.
I think you must check every load in your machine.as mention here, there is 2 problems.the machine design for 460V\60Hz.you have 415V\50Hz.
Pumps ,conveyors,heaters tend to preform not as the suppose to be.
You need to exam every load.
In most of the cases you will need just to adjust overloads.
In some other cases you will need to change parts cables ext.
I deal with that a lot.Some customer of mine order in the States machine with out to ask.When they get the machine the problems appear.

One of my customers order machine in Taiwan.He traveled to see the machine to check the capacities.
I told him to take me with him,he refused.Its too expansive.
He spend 3 weeks there,until he was satisfied.
When we started the machine here,we got 20% less production.
The main motor 150HP , design for 60Hz we have here 50Hz.
For 10 years he paid for what he saved at that time. 10 years 3 shifts 20% less.

 

[Gilbert W]

I must be missing something here. If I'm not mistaken your hz is 50 correct? I would think the motors will deliver the same torque at 415V 50 hz as when it's powered by 480V 60 hz. The only problem aside from some people being offended, is that the motors will be running at 5/6 the speed that they were in the states. Also the total horsepower will be 5/6 of what is was in the states. But the torque will be the same.

Pumps and cooling fans not on a VFD are running at 5/6 speed. This is something that could easily be overlooked and problems might not show up until the machine is fully loaded.

If you install a system step up transformer be careful because some relays are rated 120V 60Hz and 110V 50Hz and may be over voltaged if the transformer adjusts the control voltage back to 120V.

 

[jimbo346]

I may have used too strong a comparison to get my point across, which is this, and only this. I thought that demanding to have the post removed was a little excessive.
My exposure to different cultures across the world have taught me that one persons use of certain words can light a fire in one room and roll of the shoulders of everybody else in a different room. I'm sure that every practicing Muslim, Christian, Hindu, Buddhist, etc, probably didn't care for the header. As I didn't. Everybody has the "right to be offended". But, I feel that the entire matter would have been better served if the conversation had gone more like: Could you please not use profanity in your header next time. (Cudo's to the person who suggested that he change it.)
I will now gracefully bow out of this conversation.

 

[HJTRBO]

Good morning, or good night, where ever you are. Originally I was going to hook the motors up as a low voltage configuration, but now that I know the 460V is Line to line. This would give me in America 277 Line to star point, I will have 240V line to star point. Excellent

As for the VSD they are very nice, each VSD has 6 channel encoder feedback from our motors. We do not wish to replace our motors, as from what I understand, the imperial measurements, we cant get an IEC standard motor, also the motors have built in encoders, so the cost gets pretty nuts. In saying that, there is nothing wrong with the existing motors. The machine has been well maintained.

9 wires aren't what HAD me confused, I would much have preferred a 12 wire so that I could wire this motor in delta, as my running current is going to be quite large. The confusion I had was your low voltage distribution. Now I know that you have 460vac phase to phase. In heinsight, I could have just asked for the answer to that!...

 

[sodonnell]

eurotherm 690

I agree with OpZed on the drive dealing with the lower power. the drive doesn't even hiccup at the change in voltage to the lower side but it will do a real catastrophic meltdown if the voltage surges above 480. the drive basically looked at a set of parameters and adjusted itself accordingly. So find the parameter that identifies our particular voltage and adjust accordingly.
Hope this helps.

 

[HJTRBO]

The power through the drive will remain the same, however the lower voltage will give rise to a larger current.

The control panel was built here in Australia, so i've had a look at the overloads on the DOL's but there is enough range to cover that side of things.

The drive is spec'd at 7.5kW where it should have been spec'd at a 10kW to allow for the higher current. I just done some quick calcs looks like the line current will increase at full load by just 2 amps @ 50Hz. Looks like we'll be ok. I will wind down the current limit, and conservatively set the thermal protection to be on the safe side.

Thanks
Nathan

 

[DickDV]

Since there is a VFD in front of the motor, I think Vaughn and Gilbert have it right as long as you can tolerate operating at 83% (5/6) speed.

Put the correct high voltage nameplate data into the drive, and set the maximum frequency for 52hz. Your drive will run out of voltage just as it reaches 52hz. The motor will develop nameplate torque up to the 52hz point.

If you must recover all of the speed, then I would rewire the motors for 230V and put those nameplate data items into the drive. You would set the maximum frequency for 60hz. The motor would be seeing 585v output pulses from a drive operating on a 415V input but it has insulation for 480V (660V peak) so that shouldn't be a problem. Of course, the current is going to be double for the lower voltage setting so the drive may be undersized. Pay no attention to hp or kw on a job like this. Use amps only for sizing purposes.

If the drive has the ampacity, you could even get constant torque out of the motor above 60hz by setting the motor nameplate data in the motor at 415V and 104hz. With the motor wired in the low voltage configuration, you would actually get more that nameplate hp or kw. 415/240 x hp to be exact. It would only be available thru overspeed, however.

 

[HJTRBO]

DickDV thansk for that good dose of knowledge. I was wrong the post above yours with my power been the same for the lower voltage. I scratched my head, but managed to remember the stuff I learnt at trade school. I came up with a reduction of line current of 9% and a power reduction of 18%. There was no suffering of torque, because we spin at 50Hz here so that offset the torque loss. Of course thats all worked out at line voltage, so i'm unsure as to how relevant all that is once a VSD gets smacked up its bum.
With regards to chucking in different nameplate data to get different results, I think its something that I seriouslt need to explore here and I will mention too the right person, thanks for letting me know its an option. We have a drives specialist contractor who I think i'm gonna call to bail me out on this one.

Don't we love a challange.