VFD Brake Resistor vs Motor Brake

Forgive me if this has been asked and answered. I'm retrofitting my Deckel FP1 that has a dahlander motor with a VFD. I've found a few threads and resources discussing these motors so have figured out how to hook the VFD up to the high speed windings.

My question is about the brake. The VFD I have has the option of adding a braking resistor. When looking at the data plates of the Siemens motor it shows a Brake (Bremse). I'm assuming that this is some other form of brake and not a resistor that the VFD is looking for. I thought I would asked some more experienced folk, however, so I could learn something and hopefully be proved wrong. What sort of brake is the dataplate showing?

Thanks

Here are the data plates. Top is from the brake. Middle is from the wiring box cover and the bottom is from the motor.



Teryk

The purpose of that brake would be to stop motor rotation after a complete motor stop.


The purpose of the VFD braking resistor is to aid in rapid motor decelleration.

The brake on your photo is activated when the voltage is off. The brake will release when the voltage comes on. That means your spindle is locked when the lathe is stopped. That is inconvenient when you want to move the chuck to find a position so you can use the key. ( There are machines as have a more clever logic as also releases the brake after stop).
A VFD with brake resistor is much better. You can have a softer stop and you can have a softer start. You can stop the spindle within one turn at low rpm. By a switch on the bed you can stop the spindle and carriage under threading procedures. It repeats the stop very precis every time. Then you also have the advantage of variable rpm.

Is it correct, then, to state that the brake in the motor is essentially a generator/alternator of the voltage and amperage listed on the data plate? If so, doesn't there need to be some electrical resistance to slow the motor?

There is definitely some resistance to turning when the motor is stopped but nothing that can't be overcome by the gearing.

I have an understanding of the advantages of the VFD and how it brakes the motor. Just trying to understand how the built in brake works. Mostly out of curiosity.

Thanks

Teryk

Sent from my XT1710-02 using Tapatalk

The 'built in brake' is just an electromagnet, a spring, and a friction disk. When the motor is not powered, spring holds friction disk against a machined surface on the motor's rotor, or against a secondary (replaceable) disk face on the motor shaft.

When energized, the brake's electromagnet pulls the brake disk to released, allowing motor to turn.

DaveKamp said:

The 'built in brake' is just an electromagnet, a spring, and a friction disk. When the motor is not powered, spring holds friction disk against a machined surface on the motor's rotor, or against a secondary (replaceable) disk face on the motor shaft.

When energized, the brake's electromagnet pulls the brake disk to released, allowing motor to turn.

Click to expand...

Awesome, thanks Dave. Appreciate the insight.

Teryk