VFD braking

After installing the brake resistor and messing with my 1 HP drive on the Bridgeport...

Here's something I do not understand.

Depending on frequency and belt ratio, the drive would have a differing minimum stopping time. No surprise here, since stopping a motor involves dissipation of its kinetic energy, which depends on the RPM of the whole rotating mass. The more RPM, the more energy, the longer it takes to dissipate.

That's kind of obvious.

But my VFD only offers a fixed time braking option, I can set a "stop time" regardless of run frequency or belt ratio.

If so... Why does my drive (as are other drives that I have seen) does not offer a braking option that would amount to "just dissipate as much energy as it can without causing overvoltage"?

This VFD can stop my mill, at low frequency and RPM, in a small fraction of a second.

At higher RPM, it takes longer.

What is so difficult about writing software that would take it into account?

The provided function to enable overvoltage protection, just does not seem to be working.

There must be something that I am missing.

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No..apparently you have a "dumb" VFD

There are others out there that are far far more able.

Did yours ask what max amps your motor draw? Does it offer "autotune"?

There are VFDs..and VFDs

On the other hand..you are unlikely to be tapping at 3000 rpm either so if it takes .5 seconds longer to stop..so what?

Dont over complicate things


"Obama, raises taxes and kills babies. Sarah Palin - raises babies and kills taxes." Pyotr Flipivich

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Gunner Asch

I will try to find out if there are sm,arter ones, just for the kicks I will call drives warehouse.

I could enter that stuff, yes. But it is optional.

I just think that it is bad, to be sub-optimal like this.

Anyway, I know by heart by now that it is parameter 1-10 and it is easy to change. So I can change it to be 0.3 sec for tapping and 1 sec for everything else.

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