twin motor phase converter

I did the same thing. It worked well. Of course, I no longer need the phase converter, since I moved my business to my warehouse.

What is the advantage to rotary phase converters vs VFD's? I never didn't have 3-phase so I never had to bone-up on this stuff. I just figured that if I ever wanted equipment at home, I would get the appropriate VFD and be done with it. Obviously, I'm missing something.

Tom Gardner fired this volley in news:0NydnV10J-Sc-

IF you have the motors already, it's cheap. IF you can live with the imbalance of phases that's likely to occur (usually fine when running motors, and _can_ be tuned out) it works nicely. They usually occupy a good deal of space (although I've converted a machine's own 3-phase motor to run on single-phase with caps and a start relay, in the past)

VFD's tend to be noisy electrically, and more expensive than "scrap- built" rotary converters. They're also quieter acoustically.

Rotary converters and rotary generators used to be the only way to accomplish the task, so they stick around, and might even suit better depending on budget and space.

Lloyd

No shit, Sherlocks.

Rotary converters are much cheaper in the larger sizes. The VFD is smaller , close to the same price in small sizes, and let you vary the motor speed.

Dan

VFDs cannot operate any control systems.

no plug-reversing motors with VFD's for one

MikeB

Ignoramus14718 fired this volley in news:PcmdnY4D-cX9D6rPnZ2dnUVZ snipped-for-privacy@giganews.com:

Not even close to true, Ig.

VFDs, with proper low-pass filtering work fine on 3ph controls.

Lloyd

BQ340 fired this volley in news:523799df$0$63180 $ snipped-for-privacy@ngroups.net:

That's a matter of planning, rather than a specific advantage or disadvantage. The application matters.

VFD's decelerate then re-accelerate when switch-reversed.

RPCs do it more rapidly, but NOT instantly, which might be wanted in some applications. They also severely stress everything while doing it.

Lloyd

And if you plug reverse a big enough motor with a big enough inertia, it may happen that the motor will keep the rotation, but the phase converter idler willr everse.

Ignoramus14718 fired this volley in news:B_adnQTa6JTiO6rPnZ2dnUVZ snipped-for-privacy@giganews.com:

Yup! But I don't know (off-hand) of a VFD that will reverse its phase arbitrarily, load or no.

Lloyd

#1 advantage is you can run multiple devices off one (1) rotory converter.

#1 DISadvantage of VFDs is you can only run one (1) device off a vfd.

Gunner

"The socialist movement takes great pains to circulate frequently new labels for its ideally constructed state. Each worn-out label is replaced by another which raises hopes of an ultimate solution of the insoluble basic problem of Socialism, until it becomes obvious that nothing has been changed but the name. The most recent slogan is "State Capitalism."[Fascism] It is not commonly realized that this covers nothing more than what used to be called Planned Economy and State Socialism, and that State Capitalism, Planned Economy, and State Socialism diverge only in non-essentials from the "classic" ideal of egalitarian Socialism. - Ludwig von Mises (1922)

On machines with multiple motors such as a horizontal mill...you need multiple VFDs to operate.

"The socialist movement takes great pains to circulate frequently new labels for its ideally constructed state. Each worn-out label is replaced by another which raises hopes of an ultimate solution of the insoluble basic problem of Socialism, until it becomes obvious that nothing has been changed but the name. The most recent slogan is "State Capitalism."[Fascism] It is not commonly realized that this covers nothing more than what used to be called Planned Economy and State Socialism, and that State Capitalism, Planned Economy, and State Socialism diverge only in non-essentials from the "classic" ideal of egalitarian Socialism. - Ludwig von Mises (1922)

Karl, if you are going to run several machines off of the same converter buss then probably best to first balance your idler under no-load condition and then add correction capacitors at each machine on an as-needed basis.