PowerFlex 525 braking options?

[ceilingwalker]

Hello all. I have a parts elevator in a very dirty environment. I have used VFD's a lot over the years but I have never had to have one with a holding brake.....if that's even possible. Because this is vertical and will drive a load up to 4klbs with a 50:1 gear box I need to have it hold a position and, should power fail, not drop the load. All of these parameters tell me I will need a servo motor and amp but I wanted to check here to see if I have any options for a VFD and a holding brake. I am not concerned about positioning, that could easily be established with a discrete field device. I realize I could do this with a mechanical brake but with spatial limitations and the nasty environment, an electronic brake is my best option. Thank you

 

[jdbrandt]

Hello all. I have a parts elevator in a very dirty environment. I have used VFD's a lot over the years but I have never had to have one with a holding brake.....if that's even possible. Because this is vertical and will drive a load up to 4klbs with a 50:1 gear box I need to have it hold a position and, should power fail, not drop the load. All of these parameters tell me I will need a servo motor and amp but I wanted to check here to see if I have any options for a VFD and a holding brake. I am not concerned about positioning, that could easily be established with a discrete field device. I realize I could do this with a mechanical brake but with spatial limitations and the nasty environment, an electronic brake is my best option. Thank you

I would investigate ABB's VFDs...they have a Hoisting Package for their VFD, especially configured for what you are trying to do.
A Toshiba S7 would work, too.
You need to investigate using BOOST injection.
-or-
Consider a torque-activated brake motor...Mannesman Demag. Pretty cool stuff.

 

[cardosocea]

I believe PF VFDs do have a configuration output for a brake signal. However, I believe some people have had issues with it before because of when it decided it was time to release the brake. Can't remember exactly what the issue was, but perhaps it was here.

 

[JeffKiper]

Ive used Powerflex 750 families with load proving. I dont think the 525 have that feature

 

[jaden]

Because of your requirement to hold the load even in the event of a power failure, I think your only choice is a spring actuated, electrical release mechanical brake.

 

[GaryS]

What you want to do is simple I have done many crane systems over 30 years
Here it what I would use
Impulse VG+ Series 4 | Magnetek Pricing Catalog (magnetekdrives.com)

The VG+ can suspend the load on the hook as long as you have power
As with all Hoist motor you still need a Load brake on motor that will engage and hold the load in the
event of a power failure.
The Impulse drive have proof of torque as standard and with hoist drives all motion is UP first ( to prove torque and motor control ) then down if commanded if the proof of motor control fails the drive faults out and engages the load brake.
With the encoder you can read the actual hook position.
One word of caution with all cable hoists the cable will stretch over time and load so you need to consider that in your control program. You could consider using a laser measuring system.
But with all systems they must be evaluated individually to determine the best system to use.

Right now Magnetek is quoting long lead times so you may want to look at Yaskawa
Their GA800 Series drive will do the job just as well and have better availability
In reality Magnetek crane drive are Yaskawa drives with custom firmware to make them better for cranes the best choice for cranes.

 

[Rob A]

We use the Powerflex 525 for running the hoist in the majority of our machines. You can configure one of the outputs on the drive to EM brake control. We use this to control a contactor that controls the brake on the brake motor. Our hoists can lift 3klbs and has a 40:1 gearbox. You will also need a braking resistor connected to the VFD. This will prevent buss overvoltage faults when decelerating in the down direction.

 

[cidchase]

Yes, I recommend using a brake motor. I like to let the VFD accel just a tad before releasing the brake to prevent the load from dropping at startup. A braking resistor is generally considered critical for decelerating the load when lowering. Selective use of counterweight also is your friend. IMO.

 

[ceilingwalker]

Some excellent ideas here! Thank you

 

[JeremyM]

Hello all. I have a parts elevator in a very dirty environment. I have used VFD's a lot over the years but I have never had to have one with a holding brake.....if that's even possible. Because this is vertical and will drive a load up to 4klbs with a 50:1 gear box I need to have it hold a position and, should power fail, not drop the load. All of these parameters tell me I will need a servo motor and amp but I wanted to check here to see if I have any options for a VFD and a holding brake. I am not concerned about positioning, that could easily be established with a discrete field device. I realize I could do this with a mechanical brake but with spatial limitations and the nasty environment, an electronic brake is my best option. Thank you

The PF525 drive already has a pair of NO/NC relay contacts that can be configured to respond to the drive's Active state bit.

When the drive control unit loses power, they return to NO/NC.

The Active bit also changes state at the beginning and end of the accel/decel ramp, so you should get reasonably smooth on/off braking.

 

[GaryS]

I feel I need to inject something’s into this to help other understand
A hoisting application is a special application that must properly designed to get the best results
First you have to understand about hoist’s
With all hoists you must have an motor brake that sets when the motor is not powered and is released when the motor is power.

Most smaller Hoists, under 10 tons have a mechanical load brake built into the gearbox. It doesn’t matter about the gearbox ratio that only is used to figure the load ability and speed.
When a mechanical load brake is used the motor must be turning to lower the hook so direction is important. Hoists rated over 10 tons may or may not have a mechanical load brake depending on the manufacture and model. Hoist over 20 tons will rarely have a mechanical load brake again it depends on the manufacture and model and with hoists over 30 tons it is very rare to have a mechanical load brake. It just that is very difficult and expensive to build a gearbox that size with a load brake.
So you need to judge you needs carefully.
Now we come the drives most VFDs will do the job on smaller hoists. While many drive manufactures claim to have a drive that are rated for hoisting, in fact that depends on how you come to that rating. I know of some that just put a label on the standard drive. With most drives used today you will need a brake resistor ( DB Resistor ) is most because there are some drive available now that are 100% linr regeneration so the braking energy is sent back into the power line.
I know that Magnetek drives are specifically designed for crane duty. And many crane manufactures relabeled them as their own. I can talk about because I have been designing crane systems using them long before they were Magnetek, before they were Electromotive, they were EMS back then. And you are not going to do better.
Now as for the idea of ramping the motor speed up a little with the motor brake set would be a bad idea. You could cause the drive to trip on a fault, increase ware on the motor brake reducing its service life. And if you have a gearbox with a mechanical load you gain nothing.
We all should strive to the best and safest control system we can.
I have seen many crane system that were poorly designed and unsafe where the operator were unaware of problems until something goes wrong.
As I stated before I would recommend using a Vector Drive for this application it will give you the best control.
I may note here, this is a good place to ask questions, if you don’t know then please ask questions and learn you should also look at other sources most manufactures tech support is a good place to ask questions as well. please keep in mind your will get may opinions here some good some bad it’s up to you to take from it and learn.

 

[ceilingwalker]

I feel I need to inject something’s into this to help other understand
A hoisting application is a special application that must properly designed to get the best results
First you have to understand about hoist’s
With all hoists you must have an motor brake that sets when the motor is not powered and is released when the motor is power.

Most smaller Hoists, under 10 tons have a mechanical load brake built into the gearbox. It doesn’t matter about the gearbox ratio that only is used to figure the load ability and speed.
When a mechanical load brake is used the motor must be turning to lower the hook so direction is important. Hoists rated over 10 tons may or may not have a mechanical load brake depending on the manufacture and model. Hoist over 20 tons will rarely have a mechanical load brake again it depends on the manufacture and model and with hoists over 30 tons it is very rare to have a mechanical load brake. It just that is very difficult and expensive to build a gearbox that size with a load brake.
So you need to judge you needs carefully.
Now we come the drives most VFDs will do the job on smaller hoists. While many drive manufactures claim to have a drive that are rated for hoisting, in fact that depends on how you come to that rating. I know of some that just put a label on the standard drive. With most drives used today you will need a brake resistor ( DB Resistor ) is most because there are some drive available now that are 100% linr regeneration so the braking energy is sent back into the power line.
I know that Magnetek drives are specifically designed for crane duty. And many crane manufactures relabeled them as their own. I can talk about because I have been designing crane systems using them long before they were Magnetek, before they were Electromotive, they were EMS back then. And you are not going to do better.
Now as for the idea of ramping the motor speed up a little with the motor brake set would be a bad idea. You could cause the drive to trip on a fault, increase ware on the motor brake reducing its service life. And if you have a gearbox with a mechanical load you gain nothing.
We all should strive to the best and safest control system we can.
I have seen many crane system that were poorly designed and unsafe where the operator were unaware of problems until something goes wrong.
As I stated before I would recommend using a Vector Drive for this application it will give you the best control.
I may note here, this is a good place to ask questions, if you don’t know then please ask questions and learn you should also look at other sources most manufactures tech support is a good place to ask questions as well. please keep in mind your will get may opinions here some good some bad it’s up to you to take from it and learn.

Excellent info! Thanks much.