Testing The VFD, Break Resistor and Wiring to AXBBE

[voyager1972]

marky68 my biggest fear was that i would make a bollocks of it ,once i got started my confidence came back and everything went ok , the only thing i need to sort now is the touchprobe as those spindle have ceramic bearings , im not sure how to get around it yet

[marky68]

marky68 my biggest fear was that i would make a bollocks of it ,once i got started my confidence came back and everything went ok , the only thing i need to sort now is the touchprobe as those spindle have ceramic bearings , im not sure how to get around it yet

I know the feeling, I'm treading slowly with it.. a lot of research done so far. It seems a bit of a black art probably as every machine is different.

[marky68]

I set the Decel time to 3.5s

Yeah I'll have a go... so, just to be clear,

Do I set Voltmeter to DC... I know it goes in as AC but then it gets converted at some point to DC, then back again to AC, is that right..?
and just put the Red on the DC+ or R+ Terminal that the Brake Resistor is attached to and the Black to the R- Terminal that the Brake Resistor is attached too?
and take the reading as I hit stop

Not sure if this helps as it's a different VFD and spindle to yours but i did find out that if you don't get the parameters just right then there is no braking through the brake resistor.

[Phil Mayor]

Hi Marky,

it might help, it certainly gives a better explanation of what the parameters do, I'll have a look when I'm home later, cheers for this

[Phil Mayor]

Had another message from the Supplier saying I should try a 1500w 75 ohms Brake Resistor to be sure mine isn't broken!

So I've quickly tested the Volts across the Breaking Terminals (R+ and R-) and had absolutely no Volts showing after pressing stop on the VFD. (see vid)

Is this enough to say to the Supplier that there isn't an external Brake Circuit on this VFD or are there more tests I can do to confirm 100%

https://youtube.com/shorts/Vk_4jPkJnHg

[Muzzer]

Well certainly there's no brake resistor action going on there. You can check the resistor is still intact with your DVM. Obvs no need to actually replace it to check that - but with no voltage, it's rather academic to begin with.

The other option is as marky68 says - some parameter somewhere that isn't right, preventing it from working. A VFD without a braking resistor is pretty useless TBH.

Have you definitely selected braking resistor rather than DC braking?

[Muzzer]

I have to admit I took the easy way out and coughed up for a Yaskawa GA5 (latest generation) last time round. These are £390 plus £80 for the dedicated EMC filter ie basically £470 all in. https://inverterdrive.com/group/AC-I...GA50CB018ABAA/. That might seem a bit extravagant but at least with these you know they will work and should be reliable. They are proper industrial parts with 150% overload (60 seconds) and will run at full power all day long (as if!!). The setup software is pretty slick too of course.

Most mfrs offer up to around 4kW maximum in 230V single phase, so above that the choice is rather limited. What power are you looking for here?

[Phil Mayor]

Hi Muzzer,

I thought I'd give the VFD another test as I was in quite a rush yesterday. Instead of having the prongs balancing on the (R+ and R-) terminals I placed them inside and screwed down on them to make sure of a good connection, and sure enough I did get a reading, it was around 7VDC at idle, 16vDC during acceleration and top speed, then went up to 22vDC during Braking - I tried this around 3 times with the same results...I then tried it between (DC+ and R-) with pretty much the same results.

I remember reading (Page 21) that (DC+ and DC-) terminals could be used also (not sure if this is my bad Understanding or the Chinglish) for an external brake (although I'm not convinced) so I decided to test those terminals and they're reading around 330vDC during acceleration and 370vDC on the brake - but I'm not sure I want to connect the Brake Resistor to these....?

I actually thought this VFD would be good as it had so many more parameters than my last small VFD and it was around £300, tbh it might be me, I kinda hope it is, and the penny drops and I realise there's something I've missed, but I feel like I've, checked, double checked and triple checked everythung...

[Muzzer]

Haha no, don't connect the resistor across DC+ and DC-. That is rectified mains voltage.

You misread / misremembered the words "Braking resistor is connected between R+ and R- or DC+ and R-"

The "R-" terminal is the braking resistor switch that goes low when the VFD wants to initiate braking. Otherwise it draws no current and should read 330V or so.

What is your decel time set to? If it is set nice and short, the decel should cause the voltage to rise until the braking threshold is met, at which point, voltage should appear across the resistor.

[Phil Mayor]

Hi Muzzer, my instinct was correct then, I haven't connected the Resistor to the DC+ and DC- so that's a good thing.

You say the R- should read 330v, so are those readings for the R+ and R- bad then the max it went to during Braking was 22vDC

I've had the Decel set on quite a few different settings during the test but I think it's 5 seconds at the moment, the quicker the better, so I could bring that down to 3 seconds maybe... I think I kept getting faults the last time I changed it too low, but 3 seconds might be ok...