Dynamometers

"Maynard A. Philbrook Jr." fired this volley in news: snipped-for-privacy@news.eternal-september.org:

No, I think he's perfectly comfortable with his understanding of it. It would be entertaining to watch when "understanding" meets "mains".

Lloyd

Had a bunch of them at a previous job (225D and 240D) do not profess that I understand how they worked, but do why they were needed in our application. Large slowly spinning arms with molds attached which were never truly balanced. Regenerative drives help get back *some* of the energy used to raise the heavy side as it falls and the light side rises.

Also astounded by the difference in appearance between 20 + year old drive boards and there modern replacements. Old ones are absolutely crammed with components, new one look almost bare! Will try to get a picture the next time I'm down that way...

Oh, posting from rec.crafts.metalworking. Just noticed this is cross posted to two groups I am not following.

I can't believe it..

Ring the dinner bell and they all come out of the wood work!

Jamie

The only ones I've seen have been for battery operation - wouldn't be the first thing I missed.

That control does NOT put power back into the grid. It is a "plugging" brake that reverses the torque on the motor to stop it. Standard 4 quadrant control. They call it "regenerative" braking, but in reality it is "dynamic" braking.

Explain the difference, please.

Do your own research.

So, you do not understand the meaning of 4-quadrant operation, it seems.

Here is the difference in dynamic and regenerative braking:

Obviously.

Like you, for example.

finally! we have a winner!

Jamie

Ur dense... it's obvious..

Jamie

I don't need to, I already know how it works.

Jamie

That's your normal response when you have egg on your face.

Jamie

True regenerative braking puts power back into the supply. Dynamic braking uses electromagnetic force to brake, but does not return the power to the source. DC dynamic braking can also be regenerative. AC dynamic braking is seldom regenerative. This particular unit is not. It is described as an AC 4 quadrant controller for a DC motor - and that is what it is..

In a DC system, 4 quadrant is often, (ok, usually) but not always, regenerative. Not usually on an AC supply system.

4 quadrant symple means it can controll both accelleration and decelleration in both directions - hense - 4 quadrant. Dynamic braking in a 4 quadrant AC control generally sinks (dissipates) the decelleration power, while regenerative braking in a 4 quadrant DC system generally returns the braking energy to the source.

Just my experience. 2 quadrant control can also be either regenerative or dynamic.

Please show me a circuit for 4 quadrant control of a DC motor from an AC supply that implements true regenerative braking. Explain how the output of the DC motor is syncronized to the ac line frequency. Then give me the name and manufacturer of the contoller, with specs on the amount of current it is capable of returning to the grid, and I'll believe you.

I am fully aware of DC regenerative 2 and 4 quadrant motor controls, and I know how an induction motor can be used as a generator, but I'd really like to know how to recover the power from my DC motor to the AC grid. (not just recover it into a battery)

That has some merit, but you will be required to utility mains interactive inverter and a bidirectional Watt Hour meter.

?-)

That has some merit, but you will be required to utility mains interactive inverter and a bidirectional Watt Hour meter.

?-) ================== We just got remote-reading electric meters. If installed upside-down they continue to read demand correctly and set one of the bits in the tampering word, unlike old electromechanical meters that run backwards if inverted. They appear to defeat "Net Metering" with grid-tie inverters.

The three-dot pattern represents the spinning disk. The pattern changes for every Watt-hour consumed.

-jsw