Converting 60 HZ US pump to 50 Hz: Other problems? Recommendations?

[racookpe1978]

I have a large portable US built oil filter system that (now) can only run properly on Europe's 50 Hz system by requiring a extra 60 Hz generator and fuel tank.

Obviously, renting the generator is too expensive now days, hurts sales and increases costs and setup time.

If I run at 1450 rpm (nominal 1500) instead of 1800 rpm, my flow is too small. (250 HP motor, 440-480 volt @ 60 Hz, pump is a ITT 10x12x14 3405 type with a max impeller, flow spec is 4200 gpm minimum.)

if I change pumps (and use the same motor at but at the European 380-420 volts and 50Hz ) to the larger 10x12x17 casing, It appears I can regain the flow and keep in the same 3405/3410 "family" so my baseplate still fits.

Filter, suction and discharge piping would stay the same, so I expect the resistance to be the same.

The new casing moves the pump suction and discharge lower by 1 inch - but physically I can shim up motor and pump casing back to old height. Left right distance can be compensated for.

How do I specify the coupler to ensure a match (old motor to new pump)?

Any other problems anybody can forsee?

 

[Artisi]

Yes, but can the 60Hz run at 50Hz? I would expect the answer is no and besides it wouldn't produce the same power output anyway.

I think your only answer is to source a 50Hz unit which will operate at the duty you require.

 

[BigInch]

You have changed speed and impeller to give approximately the same head as the original configuration; that's good, but as Artisi already told you, power required has increased ... by a factor of 3.

For other implications of changing Hz of the motor see,

http://www.eng-tips.com/faqs.cfm?fid=1224

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[micalbrch]

This is only about the motor issue: You can let a 50 Hz 400 V delta motor run on a 60 Hz 460 V delta net. Standard IEC motors are suitable for various frequencies/volatages. Perhaps it is the same vice versa.

 

[TenPenny]

First off, are you sure that a 10x12-17 3410 would have the same dimensions as a 3405? I think that at the least, the overall width of the pump (flange to flange) is different, and I'm pretty sure that the foot mounting holes are different, too.

You know that the system works with a 250 hp, 1800 rpm (60Hz) motor. I'd look into using a motor with a VFD, so that you can use the 50Hz supply, and run it at 60Hz. Check with your motor supplier to find a 50Hz motor that will give you the power you need at 60Hz, and find a suitable VFD. That would be the first avenue I'd investigate.

 

[BigInch]

I'm not much at actually selecting VFDs, but I'm just wondering what price tag that comes with? Is it that one there for $ 25,000. Running on overdrive, would you need a 300 HP rated drive, or would that $ 21,000 one work?

http://www.joliettech.com/abb_acs-550_ac_drive_480v_ratings.htm

How much generator can you rent for that $ 21,000 ?

Is your existing motor rated for VFD service? Oh oh.

**********************
"Being GREEN isn't easy" ..Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com/

 

[vpl]

racookepe

This may be one of those times where you need to post this on an electrical forum -- if what you're wanting to know is how the motor is going to operate at the lower Hz.

Patricia Lougheed

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[TenPenny]

The vfd won't be real cheap, but depending on the system, changing the piping to fit the larger pump may not be easy or inexpensive either, especially when you include the cost of the new pump.

If this system is going to permanently live in 50Hz world, I'd probably rebuild it with a re-sized pump and proper motor. But if it's going to wander back and forth between 50 and 60 Hz land, I'd think about making the changes electrically.

 

[BigInch]

vpl,

he can't run it at 50 Hz, with the new impeller to make the original head at lower speed, it puts too much power on the original motor, so you'd need a new 750 HP motor, which would probably shear the pump shaft, so then you have to buy a new pump too. Heck, that's a whole new system.

then 10p said run the original pump and the 60 Hz motor off the 50 Hz wires, boosted to 60 Hz using a VFD overdrive.

Sounds good.

Then the motor's rated power is OK, just that it looks to me like you gotta pay a lot for that VFD and the motor has to be suitable to be driven by a VFD too. I doubt it is. So, then you're back to buying a VFD and VFD suitable 250 HP motor. OK, at least you don't have to buy the pump.

But for all those hastles, might as well just keep renting the generator... or buy that instead.

**********************
"Being GREEN isn't easy" ..Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com/

 

[micalbrch]

There is no problem to let a 60 Hz motor run on a VFD with 50 Hz unless the motor was sized borderlined. The VFD will be in the 15000 $ range in IP 21 degree of protection. But again: The motor needs to be suitable for the voltage, too. The frequency is one issue, the voltage another.

 

[racookpe1978]

"First off, are you sure that a 10x12-17 3410 would have the same dimensions as a 3405? I think that at the least, the overall width of the pump (flange to flange) is different, and I'm pretty sure that the foot mounting holes are different, too."

---

I appreciate all the comments -

1) Rental of the generator is several tens of thousands of Euro's per run, so the expense is in favor of being able to hook the pump to available 50 Hz power.

2) Pump dimensions (old to new) are from to the ITT catalog -> flange sizes are the same, suction and discharge centers are lower by 1.0 inch, and slightly further out from the original. The existing skid can be modified to accept the new pump. Mounting holes are the same.

3) Economic factors are mitigated by the short run time: as a temporary rig running only during plant outages, long-term economy is not "nothing" but it is not "critical" either.

4) I'll look at on-line (real world) power factors, currents, and flows in the next run. Don't know how much margin is left from current conditions at 60 cycles.

 

[TenPenny]

Just to clarify, I am 100% certain that the 3405 and 3410 have different mounting holes, but if it's on a factory-supplied baseplate built after 1987, it should have both sets of holes.