Failure of IGBT & Semikrone Diode in the ABB ACS550 Drive

Well yes, when there is a fault in the motor such as a phase to ground or loss of phase, the variable speed drive output section driving the motor(s) will most likely fail causing a short circuit on the input resulting in the operation of the circuit breaker.

Are you regularly having motors fail due to phase to ground faults?

Are you using screened cable to connect the motors to the drive? (you need to you know, it is in the manual).

In my experience it is not uncommon for a failed motor to also damage the VFD.

A classic was a system of 6 vfd's on a common (ungrounded) supply transformer. If a motor went to ground most of the vfd's were destroyed. It turned out the voltage feedback from the vfd output was referenced to ground. It was also protected with MOV's to ground. So when the motor grounded (became corner grounded) the feedback was skewed with respect to earth ground, blew the MOV's which ionized the air and, well, it let out all the smoke that was designed into the circuit. Only problem was, it raised the common reference circuit also, and blew up all the other drives.

Very expensive.

Solution was to simply ground the Y point of the transformer (a code requirement in the installation anyways). Now the fault was resticted to one vfd. So damage has now been significantly reduced.

Motors going to ground is still a problem and appears to be a manufacturing problem.

Cant you detect a ground fault or single phasing condition , then trip the drive supply before any damage ensues?

I am thinking that maybe this is an application that can be served by a current detector I have developed. Using a current transformer it will detect fault current to earth> 200mA and provide a Volt-free output via an opto-triac device.

It is a totaly passive device, powered by the fault current alone.

My suspicion is there exists a large peak overvoltage from the PWM converter and the insulation system can't withstand it. There should be a filter and the cables to the motor installed to specification for VFD's to minimize the transient voltage levels. It is a standing wave problem better handled by minimizing the source of the problem.

However, I am interested in your device, and would apreciate a link to some info.

I'm having to send a separate desciption of the photo I sent you as I dont have your e-mail details.

In the photo you see two of my current detectors, one is intended for invasive insertion into a circuit, the other uses a current transformer for non-invasive means to detect current. The size of the C.T. can be much bigger to accomodate larger cable or eaven all three phases in a multi phase supply but of course C.T's only serve in AC applications.

1. The threshold of detection for C.T.Type (1 to 100 ratio) starts at I>200mA and I Max. of 1kA. 2 Volt-free outputs are also provided.

2. Detection threshold for invassive type is + or - 3mA but can pass >10 Amp if required. The polarity of current is also determined via one of the Volt -free outputs. This type can be used on dc or ac systems and can be resitively shunted to raise current det. threshold.

The purpose of these devices is to act as almost solid wire to allow the free unhindered flow of current between its 2 main terminals just as a wire 'LINK' but the flow of that current to energise a system of LED's acting as an 'INDI'cator. It is powered by the line current and needs no other power supply.

In use there is a fractional volts loss across the device in the order of < + or - 1 Volt, it is this voltage that serves to power the LED's via 2 *10 Voltage magnification circuits. The elevated voltage serves to power a series visible and I.Red LED. The I.Red LED being the TX. part of an opto-coupler device. There are two such circuits , one for each polarity of current.

There is much more to say but I am really not used not used to authering tech. manuscripts. if you need to know more just say so.

Hope you find it interesting.

Hello,

You didn't say if any of the 6 amp breakers are also tripping at the same time as the drive failure.

If they are not tripping first, before drive failure, I would check their trip speed rating to see if they are fast enough for a semi-conductor enviroment.

I, personally, would not use circuit breakers between the drive and the motors. I would use free standing electronic overloads, ABB makes these. I think you will find the trip speed is faster with these and you can use the dry contacts in them to shut down the drive, hopefully before damage.

I have always found that it is best to go to the source when you have fault issues with your Drives. The ABB Drives Customer Service phone number in the US is 1-800-752-0696. If you are unable to find a solution from the support team, there are other sources as well.....Robert Hansen, Manf. Rep for ABB Drives is a great resource in the NW Region of US-Cell 206-979-0586, email rhansen@carmodycompany.com, Fax 206-763-4084, 800-333-3103. Another is Jeff Coxen, Territory Mgr for ABB Drives, cell 253-224-7147. Hope this has helped.

MrHandyMan

Nice gesture to help somebody else's customer to read the manual.

It sounds as though there is a maintenance problem to be solved: the <...earth fault/short circuit/single phasing...>. These things are not a feature of the <...frequency drive...>. Rather, they are a feature of the downstream cabling and whatever is connected to the end of it. Were threse things to be put right, <...earth fault/short circuit/single phasing...> is unlikely to occur, and the <...frequency drive...> will survive longer.

The practice of making one <...frequency drive...> operate <...4 Motors of 3 KW rating...> is not recommended, for a fault on any one of them will not be discriminated from the other three, meaning the <...frequency drive...> will continue to supply the fault, and the risk of its failure is higher than if four <...frequency drive...> units were in use. This feature is one of design, and a lack of proper attention to it.