DC Injector brake

[matt g]

I've been asked to fit a DC injector brake to a 3 phase motor running an industrial band saw. I've fitted them to direct drive drilling machines but not sure wether it would work on the band saw due to it being driven by a fly wheel. The problem is it runs on for about 2 minuits after being turned off. If the injector is a no go does anyone have any other solutions for an emergency stop? Many thanks for any advice, Matt.

 

[SirKit Breaker]

What about an Inverter, this will give you braking, and you can also change ramp up ramp down settings etc so you can make it stop almost dead.

 

[Knobhead]

Go for the inverter. Plug braking will either shear the motor shaft due to the inertia of the flywheel or the blade will fail due to shock loading.

 

[netblindpaul]

Use the DC injection as this is NOT plugging.
The machine has a run down now of 2 minutes now, but to comply with legislation it MUST stop within 35 seconds.
There are no real reasons why a 48" resaw cannot be stopped in around 35 sec. They run up to speed in that time, thus the mechanical forces are merely reversed.
This is easily achievable I can stop a 48" resaw in around 15 secs when the system is set up correctly, but I don't.
You MUST ensure the installation complies with PUWER98 thus BE EN 60204-1, if it does not the machine will NOT comply with PUWER98 even IF it has a brake, nor will any machine, in the eyes of HSE.
Refer to HSE guidance & the latest version of 60204-1 for further guidance.
Please remember 7671 does not apply.
I am off at 06:00 in the am for a 2hr drive to fix a machine with a DC brake on for a customer so this is my bread & butter.

Inverters are by far the best option and you can use them cleverly to regenerate, but I doubt you'll get a wood working customer to stump up the cost of installing an inverter to comply with PUWER98 on probably a 30kW motor unless you are talking about a toy bandsaw.
BTW the bandsaw is not driven by the flywheel, the band wheels are part of the machine, the motor almost certainly has a belt drive driving the bottom saw pulley.
There are other issues with the saw blades you must be aware of when re-engineering these installations, along with the supply requirements.