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Blown input on VSD board

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Western

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I'm looking for a little help please with a fault on a VSD board.

Apparently the 0-10V control line got whacked with 240V AC and caused some grief.

I appears it took out an smd Varistor/TVS ?? and 39k resistor … see photo and cct … and I am hopeful that is all that's wrong.

They brought in a new unit to compare notes with, so that has been helpful.

My main question is how to determine a replacement for the varistor or tvs diode. It appears to be a 0603 sized component.

Seeing the maximum voltage should be 10V … do I simply choose a 12V varistor … 20% higher than maximum working voltage?

A second question relates to the protection diodes … they are in a dual package … and appear to be set-up as drawn … but I haven't been able to locate any info on them. The marking is "64t"

I'm not as concerned about them as I believe they are ok … but if I have to wait for parts … I may as well put a couple of them on the order.

Thanks for any help.

20180716_170934_resized.jpg

20180716_191445_resized.jpg
 

dr pepper

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Most Helpful Member
Your assumption for the varistor is reasonable.
However if the diode package is blown that doesnt sound so good for the micro's input.
Have you tried the drive without the diode, should work so long as you dont exceed 10v, or go below 0v.
 

Western

Member
Thanks dr pepper. I was a bit nervous about the diode package initially and particularly about the micro ... but I'm pretty confident the diodes are ok ... they measure exactly the same as the one on the known good board.

I don't have three phase in my workshop, so I don't know any way of testing it without sending it back to the electrician who brought it in.

Maybe I could run the control portion of the board up with 10V ... and watch the output as I feed the control line as you suggest ... though more chance of me blowing something else up! :(
 

dr pepper

Well-Known Member
Most Helpful Member
Some drives 2.2kw or less will actually run of 1 phase 240v.
If you have the radar display module you might be able to monitor the control signal, ABB's do this.
 

Western

Member
Some drives 2.2kw or less will actually run of 1 phase 240v.

Mmm ... I have often powered up VSD's using single phase ... but that has just been to see if the control side works or not (if they have a display or some sort of feedback system)

This particular job came in without the motor ... just the VSD on its own.


For my future use (for testing purposes) ... are you saying that I could run a 3phase motor as well off single phase (if <2.2kw) ... and not just power up the control side?



If you have the radar display module you might be able to monitor the control signal, ABB's do this.

This one is very simple and has no display ... in fact I'm not even sure how it is programmed. I need to ask the electrician. I did look online for a manual but haven't been successful.

It's a SKOV fan controller ... DA 1700-6 LPC Controller 3 x 400V. I believe they are called Blue Fan.


Edit: Thinking about it ... it does have 4 inputs ... D0, D1, D2 plus the 0-10V control line ... so it probably isn't user programable past that point anyway. I need to find the manual.
 

dr pepper

Well-Known Member
Most Helpful Member
Kinda, if the drive is rated for 240v and 415v and you use it on 240 you have to configure the motor in delta connection, this way the motor is rated for 3 phase at 240v, or 3 lots of 240v, whereas in star mode the motor will run on 415v.
This only works if the drive is designed for it, newer ones tend to be.
 
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