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### 460V 60Hz Equipments

08/10/2010 9:22 PM

Our company just bought a second-hand folio sheeter line which previously running on 460V 60Hz supply. The problem now is that the equipment will be installed on 380V 50Hz power line system. After much discussion we came up with 2 ideas:

1. Rewind or replace all AC motors and reprogram inverter parameters

2. Install 3.3k/460V step down transformer with 50Hz/60Hz cycle changer

I am not familiar with the 2nd idea. Is there any practical device to convert the frequency that can take up big load?

Pathfinder Tags: frequency
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#1

### Re: 460V 60Hz Equipments

08/10/2010 10:37 PM

AC motors function based on a relationship between voltage and frequency, and as long as the relative ratio remains the same or +-10%, they can perform fine. So a 460/60Hz motor has a V/Hz ratio of 460/60=7.67:1. Your 380V 50Hz supply will have a V/Hz ratio of 380/50=, 7.6:1 ... Hey! How convenient!

In other words, your motors will run just fine at the lower voltage because the frequency changed as well. So your motors will be able to put out the same amount of torque! But here are the catches;

1. Your motors will spin 20% slower. So if they were designed to run at 1725RPM, they will not run at 1380 RPM.
2. Because motor power is an expression of torque at a given speed, and you have lowered the speed, you are effectively lowering the motor output power as well. Depending on what your motors are running, that may or may not be a problem. You will have to check the machine design specifications and compare the new data to your performance expectations.

All that said, this only applies to motors. Other things, such as older linear power supplies, may not be able to tolerate the lower voltage. Generally, switch mode power supplies (SMPS) won't care much about frequency, but you can't assume so, you have to check.

Anything with a transformer may be problematic because transformers are designed for a specific operating frequency, but usually the problem is the other way around; 50Hz transformers saturate and burn up at 60Hz. 60Hz transformers tend to be fine with 50Hz applied to them but as always, ask ask ask.

Control systems may or may not like it either, you can only know by evaluating each circuit element one at a time. If the machine was designed for use in the US, it most likely has 120V controls, something you will be hard pressed to replace readily where you are now. So I would consider changing out to a 24VDC control system if you can.

As to your specific question #2, that is usually what we call "over kill", but if you have a lot of sensitive equipment that cannot handle the issues I mention above, it may be your only choice.

As to your option 1, that is probably totally unnecessary. Any motors being run by inverters already have what you need for the frequency change, but because you cannot boost the voltage through the inverter, you will need to simply add a low cost autotransformer in front of each one to boost the 380 to 460 (or 480). the inverter inputs couldn't care less about line frequency, they just rectify it to DC anyway.

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Power-User

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#2

### Re: 460V 60Hz Equipments

08/11/2010 8:29 AM

dear,

I have seen textile factories being rewinded the similar motors, to tackle the speed problems.

But, the speed variation encounterd is only of 6%. lesser then the original speed, which they may be able to over come by VFDs in their system.

Then, there is no need of modifications at all.

Just connect the 60 Hz - 460 V motors to 380V - 50 Hz supply, factory will run..

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Power-User

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#10

### Re: 460V 60Hz Equipments

08/12/2010 2:55 AM

I think that the speed reduction is 16.6666% IE: RPM at 60 Hz/6 x 5 = 50Hz Speed

Due to the lower speed the fan will not transfer as much air and would run a little bit more hotter but it should not be a problem.

Cheers

Joe

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#11

### Re: 460V 60Hz Equipments

08/12/2010 3:05 AM

Hi J Raef, I am most impressed, I never have known that calculation for operating motors at different frequencys and voltages, I have always consulted a motor rewinder but, this I know will come in handy in the future, thanks mate you have my vote.

Best Regards

Joe

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#3

### Re: 460V 60Hz Equipments

08/11/2010 8:25 PM

The only reason to rewind all ac motor is basically to standardized with our mill motor spare parts. This is just to prevent further complication later on if someone take 460V motor to another place without refering at the motor nameplate

As for the AC motor using inventer, we might just maintain as it is by just adding autotransformer. Thanks to JRaef for highlighting the idea up.

But for DOL motor like trim blower and vacuum pump which are subjected to speed downgrade if connected to 50hz, we do not have much practical choice other than replacing those motors.

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#4

### Re: 460V 60Hz Equipments

08/11/2010 8:36 PM

Think that through a little; replacing the motors (or rewinding them) will not change the speed! The speed is based on the number of poles and the applied frequency. You will have the same problem.

By the way, if you send those motors off to be "rewound", the motor shop will take them from you, change the nameplates to say "380V 50Hz, (lower) RPM, (lower) kW", and send them back with a bill for rewinding them! There is nothing to rewind that will make a difference because of what I said. You cannot change the kW rating or speed by rewinding. The speed / power rating issue is a problem for the machine design, the motors are no different.

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#5

### Re: 460V 60Hz Equipments

08/11/2010 11:11 PM

GA for both posts JR. Nicely covered.

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#6

### Re: 460V 60Hz Equipments

08/11/2010 11:34 PM

Another option would be to install a 460VAC, 60Hz 3-Ph generator driven by a "local" 380 VAC, 50 Hz motor (or install a small CoGen unit with same outputs). Everything would work as before with small added operating cost (or none with proper CoGen system).

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Active Contributor

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#8

### Re: 460V 60Hz Equipments

08/12/2010 2:10 AM

Another good suggestion. will consider that one with our project team. Thanks Energygod

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#7

### Re: 460V 60Hz Equipments

08/12/2010 12:07 AM

One more thing that I did not see mentioned. If you are going to run the motors at 50Hz, watch that they dont overheat. The internal cooling fans in the motors will not move as much air due to the lower speed. This may or may not be a problem. Depending on how conservatively they were designed.

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#15

### Re: 460V 60Hz Equipments

08/12/2010 11:04 AM

If the motors are supplied by inverters (vfd's) as the original post indicated, the inverter output to the motor would be 60Hz nominal anyway. As JRaef said, the inverters don't care about incoming frequency, it's immediately rectified to DC. The inverter output is already compatible with the existing motor it supplies.

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#9

### Re: 460V 60Hz Equipments

08/12/2010 2:12 AM

check the normal load amps if it is within the name plate current it should be okay, only the motor rpm will be less.

Anonymous Poster
#12

### Re: 460V 60Hz Equipments

08/12/2010 5:10 AM

Hello Sir..

As per your query i would like to suggest you that you have to installe a Servo Voltage Stablizer On the LT side of your Existing transformer and supply the output voltage of that stablizer to your machine. With the 380 Volts 50 Hz supply your machine will work fine.

Specification of Stabilizer.

I/P Voltage: 320-480 Volts 3-Phase, 50 Hz

O/P Voltage: 380 Volts 50 Hz.

with this requirement your machine will work fine.

i'm also working in stabilizer company and we have already supply the stablizer for that kind of requirement

For further detail feel free to contact me.

Kunal Gautam

094645-28115

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Join Date: Aug 2010
Posts: 3
#13

### Re: 460V 60Hz Equipments

08/12/2010 5:12 AM

Hello Sir..

As per your query i would like to suggest you that you have to installe a Servo Voltage Stablizer On the LT side of your Existing transformer and supply the output voltage of that stablizer to your machine. With the 380 Volts 50 Hz supply your machine will work fine.

Specification of Stabilizer.

I/P Voltage: 320-480 Volts 3-Phase, 50 Hz

O/P Voltage: 380 Volts 50 Hz.

with this requirement your machine will work fine.

i'm also working in stabilizer company and we have already supply the stablizer for that kind of requirement

For further detail feel free to contact me.

Kunal Gautam

094645-28115

Power-User

Join Date: Sep 2006
Location: New Jersey, USA
Posts: 165
#14

### Re: 460V 60Hz Equipments

08/12/2010 6:04 AM

You don't mention wether or not the motors are controlled via VFD but if so most (as JRAEF said you have to ask) will allow you to power the VFD for 380/50 and run the motor at 460/60. Since the incoming AC is converted to DC before being chopped up the in and the out don't have to be the same. However current draw will increase on the line side so that would have to be taken into consideration.

As for the controls if your machine has its on dedicated control transformer for 120V controls you should just be able to switch out the 460-120 for a 380-120 transformer.

Shawn

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#17

### Re: 460V 60Hz Equipments

08/12/2010 1:56 PM

You cannot supply a VFD with 380V and have it put out 460V, it cannot create voltage from thin air. That's why I said they would need autotransformers in front to step the voltage from 380 to 460V.

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#18

### Re: 460V 60Hz Equipments

08/12/2010 2:08 PM

I'll just shut up now as I'm an idiot. I've done the opposite (460 IN/380 OUT) and didn't stop to think.

Shawn

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#19

### Re: 460V 60Hz Equipments

08/12/2010 2:29 PM

No your not an idiot, you just did what we all do sometimes. Didn't stop to think it through. I do that a lot...

I only responded because there are people who read this forum and take everything posted as gospel.

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Participant

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#16

### Re: 460V 60Hz Equipments

08/12/2010 11:30 AM

Hey we don't have to install VFD. the machine will work on 380 Volts 50 Hz very well...

Anonymous Poster
#20

### Re: 460V 60Hz Equipments

08/12/2010 4:08 PM

Hello,

The replays on your problem also give me positive ideas in my future needs. Specially the replay of JRAEF, thanks anyway. Nonetheless, if you required the same rpm hopefully you have some space to introduce a reducer (gear box), belt pulley, etc.

erel

Anonymous Poster
#21

### Re: 460V 60Hz Equipments

08/13/2010 2:58 PM

has anyone seen the film "Not another teenage movie" (or something like that). Well this post is another "Not another 50Hz/ 60Hz post". JRaef (who by the way is excellent in these matters) never seems to tire in answering these questions.

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#22

### Re: 460V 60Hz Equipments

08/13/2010 8:14 PM

yes I do... but after I have ignored a few, I get interested again.

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#24

### Re: 460V 60Hz Equipments

08/16/2010 12:05 AM

Well you get a gold star (and GA) from me.

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#23

### Re: 460V 60Hz Equipments

08/15/2010 12:10 PM

Hook it up and try it! The inverters first rectify the incoming voltage then create the voltages based on the parameters selected. If you do not run at full power I'll be willing to bet it will work.

I have ran 3-Phase 460 servos on 1-phase 240, just not at full power.

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