VFD Control Cabinet / EMI Noise Filter Sizing

[mightymig]

Hello,

At the danger of exposing myself for playing with electronics I understand just enough of to be dangerous with, could anyone please help me with a couple questions regarding sizing an EMI noise filter on the input line to my VFD?

Some background:

I have the following model of VFD - Huangyang 2.2kw FC01-2R2G-2-B

In the manual Huangyang specify the following:

Maximum input current - 15 amps
Cable sizing - 2.5mm
Fuse - 32 amps
Breaker - 25 amps
Contactor working current - 16 amps

(I will use a 16 amp breaker and swap it if it’s an issue)

I have 2 questions which I would like to ask:

1. What is the inrush current when the VFD turns on? (e.g. milliseconds load to charge capacitors? - is it something like 5-10x the input current? I have emailed Huangyang on this but they’ve not come back)
2. Would a 20 amp EMI noise filter (heavy duty industrial grade) be suitable for use with this VFD, or should I use 25-30 amps EMI filter? This will be for the input side, before the VFD and connects the single phase into the VFD terminals. The model I’m looking at is Schaffner 2090-20-08 (off eBay)

Picture attached with wiring unfinished / to be correctly done, earths not connected yet etc. Contactor will be controlled with latching NC emergency stop / NO start button. Control to VFD signals is pending delivery of some 1mm CY cable.

Any electronics gurus that can help, I’d be greatly appreciative

 

[voipio]

The setup will probably require two noise filters. One on the mains input, and one on the VFD output, ideally placed close to the wire entry/exit points on the case, and tied to the case earth/metalwork. The inductors of a 20A industrial filter should easily handle the inrush current on the mains input.

 

[mightymig]

Thanks, good to know it should handle the inrush. How about the working capacity? It should be fine with the 20a rating I guess, considering the 15a maximum input draw of the VFD. The current use case in operation shouldn’t pull anywhere near that but this whole build got stupidly out of hand to power a very small 3 phase motor - but I got this deep and decided I would build it to be used with a lathe or surface grinder when I get one and then I will replace this setup for the small motor with a smaller VFD and subsequently at that stage if needed add a dedicated output EMI for the bigger machinery.

For now, output noise filtering wise I was planning on using ferrite rings on the ‘3 phase output’ instead of an EMI.

Cheers!

 

[Kram]

I cant say its the same for all VFD's or inverters but they usually have an inrush limiter so the capacitors charge at a sensibly slow speed. It shouldnt cause any issues.

 

[MetalMonkey]

James (Clough42) on YouTube has a good video on the topic, if you haven't seen it already.

 

[timgunn1962]

I have a feeling the HY drives that I have used have all had some sort of surge-limiting resistor that is in circuit initially and gets switched out shortly after power-up. I have certainly not had a problem with the ones I've used and they've been mounted in IP65 enclosures and powered through a cable with a 13A plug on the end. They've been fine on test with the 32A typeB MCBs on my ring-main circuits and I'm not aware of any problems once they've gone out.

I'm not usually a huge fan of the HY drives, mainly because I really prefer Sensorless Vector drives. However, the HY drives are the only ones I've been able to find that'll run on a small portable site generator and I've used a few as a result: maybe 8 of them over the last 15 years. All the other drives I've tried will only run from pure-sine-wave inverter generators.

 

[Agroshield]

From your description, you appear to be providing E-stop functionality by means of a contactor on the supply input to the VFD.

That is unusual and might not be best practise. It is far more common to have the E-stop as part of the VFD's control circuitry.

Effectively, every time you trigger the E-stop, it is mimicing a power cut. In that situation, the VFD's behaviour (likely an undervoltage alarm) will not be the same as a stop command received via its control inputs. In particular, you would lose any braking ability of the VFD so the arrangement you have will lead to a slower overall stop.

 

[mightymig]

James (Clough42) on YouTube has a good video on the topic, if you haven't seen it already.

My entire build and knowledge on this cabinet comes from this specific video series, however in this one he goes for a 20a EMI, yet in his more recent CNC spindle build video where he builds another VFD setup (again with a 2.2kw VFD) he used a 30a…. Hence my questions. But if I hadn’t seen this already, it would’ve been and still is a great resource. Thanks

 

[mightymig]

From your description, you appear to be providing E-stop functionality by means of a contactor on the supply input to the VFD.

That is unusual and might not be best practise. It is far more common to have the E-stop as part of the VFD's control circuitry.

Effectively, every time you trigger the E-stop, it is mimicing a power cut. In that situation, the VFD's behaviour (likely an undervoltage alarm) will not be the same as a stop command received via its control inputs. In particular, you would lose any braking ability of the VFD so the arrangement you have will lead to a slower overall stop.

Thanks for the comment and yes the way I’ve written it does come across like that. The contactor plus e-stop and start is only for turning the VFD on or off, or cutting the power entirely if there was an emergency. I should’ve also mentioned I will control the actual start / stop of the motor via a forward / stop / reverse switch, which is what controls the VFD via the programmable inputs. Cheers though.

 

[mightymig]

I have a feeling the HY drives that I have used have all had some sort of surge-limiting resistor that is in circuit initially and gets switched out shortly after power-up. I have certainly not had a problem with the ones I've used and they've been mounted in IP65 enclosures and powered through a cable with a 13A plug on the end. They've been fine on test with the 32A typeB MCBs on my ring-main circuits and I'm not aware of any problems once they've gone out.

I'm not usually a huge fan of the HY drives, mainly because I really prefer Sensorless Vector drives. However, the HY drives are the only ones I've been able to find that'll run on a small portable site generator and I've used a few as a result: maybe 8 of them over the last 15 years. All the other drives I've tried will only run from pure-sine-wave inverter generators.

HY was what I could afford before understanding the actual cost of putting a proper cabinet together. I would’ve liked a better one and have spent the moneys worth of a better one on the cabinet and other components - but I didn’t really know that’s what I took before starting out. I would still need all the extra bits plus the cost of a more expensive VFD anyway, but now I know for next time. The other option was to not get cracking on it, and it would’ve sat it in a box under my bed for 5 years

 

[Kram]

From your description, you appear to be providing E-stop functionality by means of a contactor on the supply input to the VFD.

That is unusual and might not be best practise. It is far more common to have the E-stop as part of the VFD's control circuitry.

Effectively, every time you trigger the E-stop, it is mimicing a power cut. In that situation, the VFD's behaviour (likely an undervoltage alarm) will not be the same as a stop command received via its control inputs. In particular, you would lose any braking ability of the VFD so the arrangement you have will lead to a slower overall stop.

That is also what Invertec recommended to me, with the VFD set to fast stop on power loss.
On a fast stop the VFD has to absorb energy from the motor, it does not need AC input to stop, atleast on mine.

You cant cut power on the output, or risk blowing up the output stage of the VFD.

 

[mightymig]

That is also what Invertec recommended to me, with the VFD set to fast stop on power loss.
On a fast stop the VFD has to absorb energy from the motor, it does not need AC input to stop, atleast on mine.

You cant cut power on the output, or risk blowing up the output stage of the VFD.

Yes stopping the VFD (whilst it’s under power with motor on) shouldn’t be done via e-stop unless the “e” is an actual emergency. I have a drum switch to be rewired with the CY cable to control the actual motor

 

[daleyd]

Ideally you wouldn’t use an estop input on a standard input to a drive - if you want the drive to REALLY stop, and it’s lost its marbles - would you trust it to?

On branded inverters they will have an input dedicated as STO (safe torque off) which will be guaranteed to stop the drive, as a proper safety rated input.

I don’t think there’s anything inherently wrong with either way, but on mine I tend to use the input as a “quick” stop and the e estop cuts power in case of real faecal/fan interaction.

 

[mightymig]

Ideally you wouldn’t use an estop input on a standard input to a drive - if you want the drive to REALLY stop, and it’s lost its marbles - would you trust it to?

On branded inverters they will have an input dedicated as STO (safe torque off) which will be guaranteed to stop the drive, as a proper safety rated input.

I don’t think there’s anything inherently wrong with either way, but on mine I tend to use the input as a “quick” stop and the e estop cuts power in case of real faecal/fan interaction.

I think that’s what I have, the picture isn’t representative of how it will be setup. The contactor is there to cut the single phase input in an emergency and won’t be used for anything else. The contactor isn’t wired to the VFD at all (basically transparent pass through of the power only, no control apart from in emergency) it will have its own control circuit to energise the coil but that’s it. The VFD doesn’t know it’s there. The S1, S2 and S3 terminals will be programmed for start/stop and reverse via this switch using 1mm cable which is just signals for control. Pic attached. Are we on the same page or am I misunderstanding what you’re saying?

 

[mightymig]

Overall regarding the EMI I’m gna get the 20 amp one and think that will be ok.

 

[daleyd]

I think that’s what I have, the picture isn’t representative of how it will be setup. The contactor is there to cut the single phase input in an emergency and won’t be used for anything else. The contactor isn’t wired to the VFD at all (basically transparent pass through of the power only, no control apart from in emergency) it will have its own control circuit to energise the coil but that’s it. The VFD doesn’t know it’s there. The S1, S2 and S3 terminals will be programmed for start/stop and reverse via this switch using 1mm cable which is just signals for control. Pic attached. Are we on the same page or am I misunderstanding what you’re saying? View attachment 480034

No that’s pretty much it - what I’m saying is that if you want the drive to stop 100% then you want to cut the power. On industrial drives they get around this by having safety rated inputs which are guaranteed to work in the event the drive goes faulty, tied in with monitored safety circuits etc. Usually called STO but overkill for a home workshop set up.

As far as i know your drive doesn’t have a safety rated input, so you are relying on the drive stopping, which if it’s faulty it might simply ignore the input, which wouldn’t be ideal.

 

[6ply]

On my Harrison lathe I have a contactor controlling power to the VFD. An e-stop button (24V logic) controls the contactor AND simultaneously sends a digital signal to the VFD to shut down. Without the shutdown signal, the VFD would raise a low voltage error. I can use the e-stop to power the machine on/off at any time, but during normal use I just press the separate off switch or foot brake for rapid braking.

 

[Stupoty]

From your description, you appear to be providing E-stop functionality by means of a contactor on the supply input to the VFD.

That is unusual and might not be best practise. It is far more common to have the E-stop as part of the VFD's control circuitry.

Effectively, every time you trigger the E-stop, it is mimicing a power cut. In that situation, the VFD's behaviour (likely an undervoltage alarm) will not be the same as a stop command received via its control inputs. In particular, you would lose any braking ability of the VFD so the arrangement you have will lead to a slower overall stop.

Yeah the phase controlled stop/ramp down speed can slow down the motor very quickly even with no braking resistor.

Stu

 

[Agroshield]

...you are relying on the drive stopping, which if it’s faulty it might simply ignore the input...

With my devilled apricot hat on, can you find one single credible report of a VFD going Skynet?

 

[daleyd]

With my devilled apricot hat on, can you find one single credible report of a VFD going Skynet?

No but do I want to put my trust in Chinese electronics when my fingers/arms are involved? I'd rather know that it's 100% going to stop, even if a bit slower than a ramp down stop.

If it wasn't an issue why would manufacturers bother to fit proper safety rated inputs specifically for this reason?