Dynamic Braking Resistor Fuse

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JovialBulge

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For UL applications when using a dynamic braking resistor on a PF525 it requires you to use fuse on the PF525’s BR- terminal. The recommendation in the PF525 manual is a 1000GH-025 fuse, however I can’t seem to find these anywhere in stock online. Has anyone ever come across this application or did they use another fuse? Also, how does one go about mounting a fuse like this with mounting “ears”?
 
petersonra said:
I had little trouble finding them.


I think you are reading the instructions wrong though.

Note 3 applies only to IEC applications and note 4 to UL applications. So IMO you need a fuse connected only to BR-. That would be the PV-xxxx fuse.

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If you skim further down that list the larger HP PF525 drives, 15HP and above, the BR- fuse recommendation changes from the Bussman number to the Hinode number.

The Bussman number seems simple enough to implement, that fuse has a DIN mountable fuse holder that looks exactly like a standard Class CC style fuse holder. The Hinode fuse however seems to mount to a something via the mounting ears that are attached to it, I’ve never had to install something like that before and am confused as to how that would be accomplished. Unless this fuse is small enough to where I could mount one ear to the terminal on the drive and then attach my wire to the other ear, that doesn’t seem very robust of a solution though. Any advice there?
 
JovialBulge said:
If you skim further down that list the larger HP PF525 drives, 15HP and above, the BR- fuse recommendation changes from the Bussman number to the Hinode number.

The Bussman number seems simple enough to implement, that fuse has a DIN mountable fuse holder that looks exactly like a standard Class CC style fuse holder. The Hinode fuse however seems to mount to a something via the mounting ears that are attached to it, I’ve never had to install something like that before and am confused as to how that would be accomplished. Unless this fuse is small enough to where I could mount one ear to the terminal on the drive and then attach my wire to the other ear, that doesn’t seem very robust of a solution though. Any advice there?
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Best bet is to call the guy that sold it to you and see if he can get an answer from AB tech support. I went thru the knowledge base last night and found nothing on this topic, which seems kind of odd to me.
 
petersonra said:
Best bet is to call the guy that sold it to you and see if he can get an answer from AB tech support. I went thru the knowledge base last night and found nothing on this topic, which seems kind of odd to me.
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I will give that a go Monday. I dug through the KB last night and couldn’t find much. I went back and looked at my old pdf library on my pc as well to make sure that this isn’t a footnote I have missed forever or if it was a newer requirement, it was the latter which was nice to verify.

I’m hoping AB VFD wizard Jraef chimes in here at some point because I assumed if anyone knew about this, it would be him.
 
Jraef said:
Because these newer DC high speed fuses are coming in so many different lengths, most people just use the Littelfuse LSCR series single stud holders and space them for the fuse length.
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I will take a look into those this evening thank you.
The fuses required for the 7.5 and 10.0hp 525’s seem to be an issue for me to track down as well. DigiKey or Mouser, I forget which, have the fuse holder listed for them in stock but the fuses themselves have a current stock of 0.

Do you have any other recommendations on suppliers to look into? Additionally, could I use a different manufacturers fuse if it met the specs of the recommended ones? Under the letter on the law for UL508A I would assume that I cannot considering they have a SPECIFIC fuse number listed by the manufacturer that is supposed to be used.
 
Typically UL is not brand specific, but it would need to have equivalent characteristics.

It should be noted that prior to 2020, there was no requirement for fuses on the braking transistor DC circuits at all. It’s a change that only came about when UL “harmonized” (capitulated) to the IEC standards. So it takes a while for supply issues to catch up.
 
Jraef said:
Typically UL is not brand specific, but it would need to have equivalent characteristics.

It should be noted that prior to 2020, there was no requirement for fuses on the braking transistor DC circuits at all. It’s a change that only came about when UL “harmonized” (capitulated) to the IEC standards. So it takes a while for supply issues to catch up.
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Understood. I wasn’t sure based on the fact that they call out the fuse by part number, where as say on the line side protection chart they just say amperage and fuse style, not any specific brand.

I only recently noticed this change because I was referencing a 2018 version of the PF525 manual that I had on my pc, never thought to download a new version figuring “what’s really gonna change in here anyways”
 
JovialBulge said:
Understood. I wasn’t sure based on the fact that they call out the fuse by part number, where as say on the line side protection chart they just say amperage and fuse style, not any specific brand.

I only recently noticed this change because I was referencing a 2018 version of the PF525 manual that I had on my pc, never thought to download a new version figuring “what’s really gonna change in here anyways”
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UL is what changed. It’s causing all sorts of changes to fusing requirements for VFDs.
 
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