# Allen Bradley PowerFlex4 VFD



## Electrorecycler

As long as the drive will power on and you have a copy of the manual, then it's pretty easy. The manual shows the default settings. Just go through each parameter and record the ones changed from default. Problem solved. 


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## JRaef

High DC bus faulting is usually caused by something in the load or high line voltage. Replacing it without figuring out what is causing it is a waste of money. Post some details about how you are using it and when the fault happens, I can probably help you. Looking at the nameplate though, it appears to be probably an Exhaust Fan. A really common thing that causes DC bus faults on exhaust fans is that someone is changing the speed command too fast and the motor is regenerating because the fan itself cannot slow down as fast as the drive speed command is changing. So if this worked fine for a while and just started doing this, look for something that someone changed in the HVAC system, especially something mechanical like a change in a damper or duct size. 

By the way, that's a PowerFlex 40, not a 4. Different animals. 

But to your question as asked, you can download a free software program called Connected Components Workbench that, when connected to the VFD (which will need a cable) allows you to filter out all of the parameters that are at the factory defaults, so you only see the ones that have been changed. Makes it a lot easier.


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## micromind

JRaef said:


> High DC bus faulting is usually caused by something in the load or high line voltage. Replacing it without figuring out what is causing it is a waste of money. Post some details about how you are using it and when the fault happens, I can probably help you. Looking at the nameplate though, it appears to be probably an Exhaust Fan. A really common thing that causes DC bus faults on exhaust fans is that someone is changing the speed command too fast and the motor is regenerating because the fan itself cannot slow down as fast as the drive speed command is changing.


So far, every 'High DC Bus' fault I've ever seen is because of a high-inertia load being slowed down too quickly. 

Look at the decelerate ramp parameter (I don't have a book handy or I'd look it up for you), if nothing else, just program it for a few more seconds and see what happens. 

Really high incoming voltage will cause this as well but it's not likely. Around here, it's fairly common to see a 480 system operating slightly over 500 volts. I've never had high dc bus voltage because of this.


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## power

I VERY much appreciate the time you guys put into trying to assist me here.....Thanks So Much!!! 

I was wondering about regeneration, but the motor does not even start after we cleared the fault in the VFD. The motor doesn't start period. Maybe I am wrong, but I would think the VFD could only sense regeneration (F005) upon deceleration, even if the decel time is slightly too shy.

Am I out to lunch?


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## Cow

Those Powerflex 4's and 40's are some of the EASIEST drives to setup IMO. But, a lot of it comes down to what's controlling it and how much control there is, to know if you're going to have to do much programming. If they're doing everything from the keypad or it's some other basic control, I can usually have one programmed and running in less than 5 minutes.


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## JRaef

power said:


> I VERY much appreciate the time you guys put into trying to assist me here.....Thanks So Much!!!
> 
> I was wondering about regeneration, but the motor does not even start after we cleared the fault in the VFD. The motor doesn't start period. Maybe I am wrong, but I would think the VFD could only sense regeneration (F005) upon deceleration, even if the decel time is slightly too shy.
> 
> Am I out to lunch?


What do you mean it doesn't start? After the drive trips, and you reset it, then give it a Start command again, nothing happens? If you have not interrupted the Start signal after it tripped, it may not, depending on the programming of P037

Regen takes two things:
1) the motor must be energized, because the windings need to be made into electromagnets.
2) the load must be moving faster than the relative speed of the motor. 

So when running a motor with a VFD, that relative speed of the motor is what the VFD is controlling. If the VFD tells the motor to spin at 50% speed, and the load pushes it at 45% speed, the motor is being overhauled by the load and the motor is a generator. You don't need to be telling the drive to slow down if the load has it's own motive force. In something like an exhaust fan, that might be wind, a drafting effect. That's why I said to look for something that has changed, mechanically.


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## power

@JRaef - Thanks for the reply...its clear your knowledgeable about these things. I am responding to your comment BOLD TYPE:

What do you mean it doesn't start? AFTER POWERING DOWN THE VFD, AND CLEARING THE FAULTS, THE MOTOR WILL NOT EVEN BEGIN TO START ROTATING. After the drive trips, and you reset it, then give it a Start command again, nothing happens? NO, NOTING HAPPENS, IT SHOWS IT'S TRYING TO START FROM THE BMS, EVERY ATTEMPT WE GET AN F005 (Hi DC buss v), IT DOES THAT ABOUT 3-5 TIMES, THEN F033 COMES UP, THEN F005. If you have not interrupted the Start signal after it tripped, it may not, depending on the programming of P037


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## JRaef

If the OV fault was based on the fact that the drive was trying to turn on into a spinning (or back spinning) load, as soon as it tries, it will again regenerate and trip. After the successive restart counter is done, it can no longer be reset automatically.

I still suspect that you have an issue with back spinning or windmilling. One thing you can do is check the programming of A096, the "Flying Restart" feature that allows the drive to look at and detect that the motor is already spinning, then match frequency and spin it up again. The down side to this is that if the fan is BACK spinning, Flying Restart will not know the difference, match to what it sees and run it the wrong direction for a few seconds until it sees the sequence correctly. Then it will attempt to stop it and run it the correct direction, but if the windmilling issue is still there, it may result in tripping still. Bottom line, if you DO have a windmilling situation and cannot fix it mechanically, you may need to add a Braking Resistor to the drive to keep this from happening.


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## Corysan

> That's why I said to look for something that has changed, mechanically.


The VFD controls a motor... which is part of a system. Considering the load characteristics is critical to troubleshooting industrial processes and machinery. There may be a damper that is being held open if the impeller is being turned backward by a draft. If the the mechanics of the system have changed irreparably, i.e. a design change, it may be time to consider adding a resistor to dissipate regenerated power. I don't recall if this drive has that switching capability, but I don't think so. I would disconnect the load and start the drive. If the the drive ramps up normally, it is definitely a load-based problem. If it ramps up normally, test the DC buss voltage at the DC+ and DC- terminals. It should be line voltage time 1.414 (equal to AC Vpk). If everything seems normal, the load is the problem.


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## power

Thanks JRaef and Corysan. I appreciate your help VERY much. On Monday, I am gonna look into your suggestions! Again, Thank!


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