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VFD Blew up

460Dave

Plastic
Joined
Mar 5, 2011
Location
Florida USA
Please help. I am very limited in my knowledge of 3 phase stuff. I recently got a BNP220-900 blast cabinet for my home shop. It has a Leeson 2hp, 3ph motor that runs the fan. I purchased a SZCY LLC AC 220V/2.2KW Variable Frequency Drive, 12A VFD Inverter Frequency Converter for Spindle Motor Speed Control (Single-Phase Input, 3 Phase Output) (https://www.amazon.com/gp/product/B0811BXHBQ/ref=sw_img_1?smid=A2C5T5XZXP7T50&psc=1) from Amazon. This is the first time I have ever messed with a 3ph motor, so I thought I would try it. I wired it up directly to the motor and everything was working fine (used it 6-8 times. It takes about 10 seconds or so to spin up.

Tonight, I used it 4 or 5 times. After hitting the stop button, I notices a "popping" noise when the motor was just about spun down (after 10 seconds or so). I assumed it was something under pressure that was equalizing. The 3rd time it "popped" it was much louder and the plastic cover popped off the inverter and then it smelled of burnt wiring.

Has anyone else seen something like this? It's almost like it was being fed from the motor while it was spinning down.
 
This must be VFD week....

That VFD is one of the "chinese cheapies". There have been issues with those. Sometimes the bad reputation comes from reject units being sold as new.

That one appears to be pretty similar to the Huanyang units that we don't particularly like to support. And the behavior is fairly typical for the "reject sold as new" units.... works for a while, then fails for no obvious reason.

What happened? No idea. A regular VFD should just work when run from it's own panel.

Those "cheapies" usually also have a less than useful manual. No link for that, but the Amazon page shows the "english as 3rd language" sort of bad translation (example from ad: "unit is screwed to ensure the safety and reliability of use"). It seems to have been unintentionally prophetic.

What did you do to program the unit to your particular application?

If you did your part, then the failure is probably just the sort of thing typical of a "too good to be true" price. The price was about 1/3 of what a similar unit would be expected to cost, which qualifies as "too good".
 
This must be VFD week....

That VFD is one of the "chinese cheapies". There have been issues with those. Sometimes the bad reputation comes from reject units being sold as new.

That one appears to be pretty similar to the Huanyang units that we don't particularly like to support. And the behavior is fairly typical for the "reject sold as new" units.... works for a while, then fails for no obvious reason.

What happened? No idea. A regular VFD should just work when run from it's own panel.

Those "cheapies" usually also have a less than useful manual. No link for that, but the Amazon page shows the "english as 3rd language" sort of bad translation (example from ad: "unit is screwed to ensure the safety and reliability of use"). It seems to have been unintentionally prophetic.

What did you do to program the unit to your particular application?

If you did your part, then the failure is probably just the sort of thing typical of a "too good to be true" price. The price was about 1/3 of what a similar unit would be expected to cost, which qualifies as "too good".
I didn't really do "any" programming. I set it to 60 hertz and used the "run" and "stop" buttons. Like I said. I am ignorant to what should happen. Is there a product for someone like myself that will allow me to run that motor easily? Would it be cheaper to just find a single phase motor to replace it?
 
kB makes a simple vfd, just a knob for speed. Dart makes an “ez” vfd for similar simple applications.
Both well priced and respected companies. Also both come with instructions, sad to say how this is now a premium option.
 
I didn't really do "any" programming. I set it to 60 hertz and used the "run" and "stop" buttons. Like I said. I am ignorant to what should happen. Is there a product for someone like myself that will allow me to run that motor easily? Would it be cheaper to just find a single phase motor to replace it?
The question is whether a variable speed gives any advantage to you in that use.

If not, then a single phase motor is a practical solution. If you need variable speed, then the VFD is the better idea.

Normally, one would program at least a couple parameters in addition to the frequency.

Usually there are three basic settings; motor rated frequency, motor rated voltage, and motor rated current. After that, there are acceleration time, deceleration time, and many others.

When slowing a VFD controlled motor to a stop, there are choices of method. The first is to just stop driving the motor, and let it coast down. That's good for many non-critical applications, and acts like turning off a switch.

Second is a controlled slow-down, where the VFD actually "applies the brakes". With this, the motor is made to act like a generator, so that it takes energy out of the motor electrically.

The problem is that the energy has to go somewhere, and what happens to it is that it charges up the internal power supply of the VFD. If that voltage gets too high, the VFD should shut down, and let the motor coast to a stop, just like the first choice. Poorly designed, or defective, VFDs may fail to reliably do that shut down.

The third is DC injection, where the VFD applies DC to the AC motor, which is a rather violent stop. This does not charge anything, but instead, the energy heats up the rotating part of the motor. That is not a good thing to do very often, so it is not normally used except at the end of a controlled stop as a final braking method.

What may have happened is that the VFD was set to the second option, the controlled stop, with a short deceleration time. If the VFD was actually defective, that may have caused the voltage to go too high, which may literally blow the power supply capacitors apart, and might account for the plastic cover popping off. No pictures, so can't be sure.

Possibly, in the blast cabinet, the motor drives a high inertia load, one that is hard to stop. If the deceleration time was set very short, the power supply voltage may have been driven up very fast. Either the voltage detector was defective, or it was set very high (it is often settable within limits), and the VFD simply did not react to the high voltage fast enough.
 
VFD's are not plug and play, you need to do some programming of the parameters for the specific motor/operating parameters you are using, and the VFD needs to be sized accordingly for the motor rated amps along with any derating. These cheap VFD's I usually recommend to go one size bigger then you need, and even with that they have around a 25% DOA/short term failure rate. The VFD purchased has a 1 year warranty, so contract the seller for a replacement. The vendor is listed as Shenzhen Chuangyi Trade Ltd., so good luck in trying to get a response. Typically I do not buy any electronics via Amazon or eBay, unless it is a toss if it fails.
 
I didn't really do "any" programming. I set it to 60 hertz and used the "run" and "stop" buttons. Like I said. I am ignorant to what should happen. Is there a product for someone like myself that will allow me to run that motor easily? Would it be cheaper to just find a single phase motor to replace it?
YEP! 2hp is common as dirt.
 
When you programmed to set the vfd to 60hz did you enter it into multiple programs like po2-60, po7-60, po11-60, po70-60? or just in one program?
 
I didn't really do "any" programming. I set it to 60 hertz and used the "run" and "stop" buttons. Like I said. I am ignorant to what should happen. Is there a product for someone like myself that will allow me to run that motor easily? Would it be cheaper to just find a single phase motor to replace it?
No offense but that is stupid to take a VFD out of the box and not match parameters in the software to your motor parameters.
Whatever was working for you was using default factory set parameters.

Your VFD is not top of the line but I think you selected the appropriate sized VFD for your motor hp.

Another point is the way the VFD acted. Did it burn up because it was a cheap product or because of incorrect parameters.
Do people give these lower cost VFDs a bad rep because they make programming mistakes? I don't know. The VFD should protect itself.

What I know for sure is that you better become VFD knowledgeable if you intend to use one.
I know electronics and get scared of them and what they can do.

A quiet motor RPC is another choice.
 
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If you failed to set the drive - "coast to stop" and didn't add a braking resistor then the best drive also would have popped. You were effectively feeding power back into the drive on the stop command, only a properly sized braking resister can "waste" the excess energy into heat.
 
Yup, notice "Trade" in the name ? They don't know nuthin' about vfd's, except where to buy and where to ship. It's a trading company, does everything from bed-wetting dolls to cement mixers, knows nothing about any of them.
Trading companies have long history of knowing about cement mixers.
 
I wired it up directly to the motor and everything was working fine (used it 6-8 times. It takes about 10 seconds or so to spin up.

Tonight, I used it 4 or 5 times. After hitting the stop button, I notices a "popping" noise when the motor was just about spun down (after 10 seconds or so). I assumed it was something under pressure that was equalizing. The 3rd time it "popped" it was much louder and the plastic cover popped off the inverter and then it smelled of burnt wiring.
Get the VFD in a box and return it for a replacement or refund. Might just be a infant mortality type VFD.

Next time look into the manual and do a VFD to motor test operation. It will run the motor a few seconds and sense and set particular parameters.
 
The Vfd shouldn’t take that long to start spinning, it should be immediately soon as you hit start. I’ve got 2 vfd’s and it sounds like you set 60hz in one program example “po2” and didn’t change the 400 in the other programs. You were right to connect it straight to the motor and not the panel and I’ve had excellent output from mine and no troubles to date not even a hiccup. There are many different vfd’s and it’s the cheapest and easiest way to go “in my situation” and I’m sure those that have went the cheapest brand and going through a middle man are no doubt having problems but get one that has a support line to send a text ( it’ll say they respond in 24hrs.) and please next time ( if you go vfd route again) fully program the vfd and make sure your 3 ph is in the correct wiring, this would be as in a Delta or Star configuration. I hope you get back up and running. Just take your time and research before hooking it up to the machine.
PS you can also set your start up time and brake time with these
 
I noticed your vfd does has customer tech support and refund or replacement and even some basic wiring schematics on the ad. Return it. Nowadays Amazon would probably give a refund on dirty diapers and pay for the shipping. This is what some basic wiring operations on a vfd look like. You don’t need all this, I just have all operations controlled by buttons and switches for my convenience on my lathe.
 

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If you failed to set the drive - "coast to stop" and didn't add a braking resistor then the best drive also would have popped. You were effectively feeding power back into the drive on the stop command, only a properly sized braking resister can "waste" the excess energy into heat.
Not "entirely" true. The drive "should" protect itself.

But with a high inertia load (a heavy wheel, blower, etc) the voltage can be driven up very fast. A poorly designed drive may fail to protect itself.

A really poorly designed drive may not have an overvoltage protection built in. At least not one that works on a fast rise in voltage. There has to be a certain delay to avoid false trips, and a bad choice means it can go "boom" easily.

And we have no idea if that voltage setting is adjustable (it often is) nor what it was set to by default. If set too high, it may allow damage.

Finally, cheap drives have cheap components. It may have little to do with the stop mode, and more to do with poorly rated bus capacitors, which overheat in maximum current normal operation, making the capacitors more sensitive to voltage, even within their supposed ratings. Good capacitors are expensive, cheap ones have lower ratings.

EDIT: A high inertia load means a lot of work for the drive in starting and stopping.... hence the heating comment... "Ripple current" in the capacitors is the issue, it heats them, and leads to shorter life. If poorly chosen, the life can be "very" short.

Cheap parts also often have poor QC. The percentage of "bad out of the box" parts is higher. That goes for cheaper products also. QC is not free, and managers know that.
 
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Not "entirely" true. The drive "should" protect itself.

But with a high inertia load (a heavy wheel, blower, etc) the voltage can be driven up very fast. A poorly designed drive may fail to protect itself.

A really poorly designed drive may not have an overvoltage protection built in. At least not one that works on a fast rise in voltage. There has to be a certain delay to avoid false trips, and a bad choice means it can go "boom" easily.

And we have no idea if that voltage setting is adjustable (it often is) nor what it was set to by default. If set too high, it may allow damage.

Finally, cheap drives have cheap components. It may have little to do with the stop mode, and more to do with poorly rated bus capacitors, which overheat in maximum current normal operation, making the capacitors more sensitive to voltage, even within their supposed ratings. Good capacitors are expensive, cheap ones have lower ratings.

EDIT: A high inertia load means a lot of work for the drive in starting and stopping.... hence the heating comment... "Ripple current" in the capacitors is the issue, it heats them, and leads to shorter life. If poorly chosen, the life can be "very" short.

Cheap parts also often have poor QC. The percentage of "bad out of the box" parts is higher. That goes for cheaper products also. QC is not free, and managers know that.

How to you suppose the drive protects itself?

Every drive has its heatsink, always small in relationship to HP rating. Now add a significant inertial load as a %of HP and you have an issue. If possible coast to stop will avoid it. The heat sink is designed to dissipate the waste heat generated while driving the motor @ its MAX rated capacity + a safety factor. That means most of the energy is being turned into work, only a small % is wasted. Deceleration, and even maintaining desired RPM(within a very constrained range) can easily exceed 100% of the drives nameplate rating.

I don't buy inexpensive drives, Emerson, Yaskawa, Mitsubishi, Control Techniques, testing a 30 HP Sumitomo now. Our applications are 20-150HP.

Every application which does not coast to stop uses an external braking resistor because the drives don't have much capacity to handle energy feed back from the motor, our inertia loads are high. Its very silly to ass-u-me the drive will protect itself.

Inertia WILL turn your motor into a generator and that energy feeds back into the drive, if it exceeds the wattage the drive can dissipate (listed in the specs of most drives) then you hear "pops" just like the OP describes. Continue without changing something and you have the OP's result with any brand of drive you care to try with.
 








 
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