Frequency conversion

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L

LMAO

Senior Member
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Texas
I am considering quoting a frequency converter. For some reasons a friend of mine needs to convert 480V 3000A 50Hz to 480V 3000A 60Hz. As far as I know the only ways to do this is: A) motor gen combo or B) VFD and sinewave filter. Is there any other way? :?
 
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D

__dan

Senior Member
Generally two ways, rotary (motor - gen) and statically (like a UPS or VFD but not a VFD).

If it is for occasional and intermittent use, the rotary type will be foolproof and hardened - durable. For extensive use where energy efficiency is a concern, the static frequency converter may be more efficient.

If you are looking at a static type, make sure the load will like the static type output, depends on the load. A motor or transformer load will not be fussy, but another electronic conversion type power supply may or may not match well to the first static converter's output, circuit topology.

I'm sure there a better answer on this board.
 
L

LMAO

Senior Member
Location
Texas
__dan said:
Generally two ways, rotary (motor - gen) and statically (like a UPS or VFD but not a VFD).

If it is for occasional and intermittent use, the rotary type will be foolproof and hardened - durable. For extensive use where energy efficiency is a concern, the static frequency converter may be more efficient.

If you are looking at a static type, make sure the load will like the static type output, depends on the load. A motor or transformer load will not be fussy, but another electronic conversion type power supply may or may not match well to the first static converter's output, circuit topology.

I'm sure there a better answer on this board.
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I have actually done that before; needed 380V to power a VFD but didn't have transformer but had extra VFD and sine wave filter so just ran it in V/Hz mode. Worked really great, I was actually impressed how clean the output of sine wave filter was.
 
I

Ingenieur

Senior Member
Location
Earth
2.5 plus MVA (pf ?)
big motor at 480, >2000 HP range

without knowing load profile hard to pick a method
either way big $$$$
 
I

Ingenieur

Senior Member
Location
Earth
WHY does he need to do it??? What is he powering?
where is he getting 3000 A of 50 Hz in TX?
probably converted from 60?

weird
 
I

Ingenieur

Senior Member
Location
Earth
LMAO said:
it is for powering 60Hz rated loads from a 50Hz source somewhere in Russia.
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Without details impossible to answer
load? Motors? How many? How loaded?

1 may require expensive freq conversion

2 may run fine with a 480:400 xfmr and control xfmr change
power~85%
speed will be 20% slower
pullies/sheaves, gearboxes, etc if speed must be maintained

3 just change the motors to 50 Hz

4 perhaps a gen set
if he has a gen set already perhaps increase speed

5 some loads don't 'care', eg resistance heaters, etc
some may already have drives that can be adjusted

also check with the state dept before quoting
might be difficult to send some stuff to russia
some tech might be prohibited
 
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Jraef

Jraef

Moderator, OTD
Staff member
Location
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Electrical Engineer
If the loads have VFDs or other power supplies on them, the input frequency is totally irrelevant. Lighting systems, which generally have electronic ballasts now, would also not care. Any loads that are resistive or incandescent will not care either. So it really will only affect AC induction motors.

One option, and probably an easier one to implement, would be to simply replace motor starters with VFDs, even if the variable speed isn't needed. A giant M-G set is going to be very expensive at that size and very cumbersome, inefficient and a maintenance headache.
 
junkhound

junkhound

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Location
Renton, WA
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EE, power electronics specialty
check with the state dept before quoting

Russians don't care, but serious if you are here and get caught, ITAR and all that.

Back in early 90's after the wall fell was working RACU and ARCU for the space station to accommodate the Russian station module (RACU = Russian/American Converter Unit, etc). Asked the Russian designer of MIR power system who designed the MIR pulse modulation system for their power supplies: His reply, with a devilish grin, "IBM".
 
Besoeker

Besoeker

Senior Member
Location
UK
Jraef said:
If the loads have VFDs or other power supplies on them, the input frequency is totally irrelevant. Lighting systems, which generally have electronic ballasts now, would also not care. Any loads that are resistive or incandescent will not care either. So it really will only affect AC induction motors.

One option, and probably an easier one to implement, would be to simply replace motor starters with VFDs, even if the variable speed isn't needed. A giant M-G set is going to be very expensive at that size and very cumbersome, inefficient and a maintenance headache.
Click to expand...
Or just replace the motors?
Wouldn't that be a cheaper option?
 
Jraef

Jraef

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Staff member
Location
San Francisco Bay Area, CA, USA
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Electrical Engineer
Besoeker said:
Or just replace the motors?
Wouldn't that be a cheaper option?
Click to expand...
Maybe cheaper, but easier? Maybe not. 480V 50Hz motors are not standard anywhere that I know of.

Come to think of it, that makes me question the entire 480V 50Hz issue altogether. 480V 50Hz is not a standard voltage anywhere in the world that I am aware of. Officially, Russia is 380V 50Hz. The entire issue might be based on a typo. I'd take the time and effort to be absolutely sure before buying anything.

http://www.worldstandards.eu/three-phase-electric-power/
 
L

LMAO

Senior Member
Location
Texas
Jraef said:
Maybe cheaper, but easier? Maybe not. 480V 50Hz motors are not standard anywhere that I know of.

Come to think of it, that makes me question the entire 480V 50Hz issue altogether. 480V 50Hz is not a standard voltage anywhere in the world that I am aware of. Officially, Russia is 380V 50Hz. The entire issue might be based on a typo. I'd take the time and effort to be absolutely sure before buying anything.

http://www.worldstandards.eu/three-phase-electric-power/
Click to expand...

incoming is medium voltage not 480. They can convert it to whatever they want with a transformer but obviously not the frequency.
 
D

__dan

Senior Member
LMAO said:
incoming is medium voltage not 480. They can convert it to whatever they want with a transformer but obviously not the frequency.
Click to expand...

Missed the 3000A yesterday, was in a hurry.

It really depends on what the load is. Is it one or two large loads that absolutely need frequency conversion or a wide variety of smaller loads that may have independent and unrelated needs downstream of the switchgear?

If it's a wide variety of smaller, that solution may also have a wide variety of different strategies and implementations of standard off the shelf parts instead of a large custom engineered and built power plant. What is the load?
 
Besoeker

Besoeker

Senior Member
Location
UK
Tony S said:
A former colleague has just come back from a job in Russia, cost just doesn’t seem to bother them.

It costs what it costs and we’ll pay it.
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Considering that the conversion is from 50Hz to 60Hz, what makes you think the Russians would be paying for it?
 
Besoeker

Besoeker

Senior Member
Location
UK
Jraef said:
Maybe cheaper, but easier? Maybe not. 480V 50Hz motors are not standard anywhere that I know of.
Click to expand...
Maybe not but since the conversion is from 50Hz to 60Hz you wouldn't be looking for 50Hz motors.
Rotational speed might be a problem though.
 
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