Thread: VFD advice please

All contributions to this thread are welcome Dom. Before joining this forum I had only heard of expensive phase converters and home brew type of wizardry to connect machinery running three phase motors to a single phase power supply. There is a lot of very useful info in this thread and others.

Stewie

I have two 3kW Huanyang VFDs and they've been reliable for the last 4 years (one more like 6 years). I added a potentiometer to both myself, but have another two with the potentiometer fitted in the factory (2.2kW). I also added the internals for breaking resistors to both 3kW ones and they work well too (with and external braking resistor). These are for emergency stops only in my case.
Just posting this for rference for others.

I wonder what rev ended up buying and what his experience was? I'd like to know.

Hi Joe,
I bought the Huanyang 3kw unit, and apart from initial setup (which I found a very helpful Youtube video to assist with https://www.youtube.com/watch?v=Ln0UW8RJVSI) it has been great. I did notice that the power supply cable to the VFD was more than mildly warm, but not hot, when the cyclone had been running for about 10 minutes. I don't know if this should alert me to some problem but the unit itself has never thrown up any error codes.

The motor makes an odd 'moaning' sound intermittently in getting up to speed and occasionally thereafter while it is running. This makes me a bit nervous that everything is OK but it seems to run well. I have wondered whether that sound might be a sign that a bearing is not good somewhere (the motor was bought secondhand). I don't have enough experience with electric motors to be really confident that all is well with it.

Originally Posted by rev

Hi Joe,
I bought the Huanyang 3kw unit, and apart from initial setup (which I found a very helpful Youtube video to assist with https://www.youtube.com/watch?v=Ln0UW8RJVSI) it has been great. I did notice that the power supply cable to the VFD was more than mildly warm, but not hot, when the cyclone had been running for about 10 minutes. I don't know if this should alert me to some problem but the unit itself has never thrown up any error codes.

Mildly warn is OK - more than that is not. What size cable is it? Suggest upgrade of cable to a heavier duty (2.5mm) core cable.

The motor makes an odd 'moaning' sound intermittently in getting up to speed and occasionally thereafter while it is running. This makes me a bit nervous that everything is OK but it seems to run well. I have wondered whether that sound might be a sign that a bearing is not good somewhere (the motor was bought secondhand). I don't have enough experience with electric motors to be really confident that all is well with it.

Sounds like it might need bearings - how hot does the motor get?

Yep, I concur with Bob. The cable is definitely too small in crossection. If the cable gets noticably warm, there is a risk that the junctions - where there is effectively only friction contacts - could get hot! Replce the cable with 2.5mm2 as Bob suggested.
VFDs have resonance frequencies which make some motors 'sing' as the spin up, but low frequency 'moans' are more loikely to originate in the bearings.

Thanks Bob and Joe for the guidance.
The motor itself isn't getting too hot so I suspect that what I am hearing is 'singing' mentioned by Joe. The cable to the VFD from the power point is heavy duty 15 A cable but I don't know what the diameter of the conductor is. I'll get heavier cable just for peace of mind.

Originally Posted by jhovel

........... but low frequency 'moans' are more likely to originate in the bearings.

I once worked for a 'power company' and a very common complaint from customers with some brands of ceiling fans AND VFD's was that the devices 'moaned' at the same time as the 950 or 1050Hz signal was being sent out to turn on off peak systems and non PE street lighting. In the old days when the times to send these signals was very regular and predictable, the 'moans' were heard at the same time every day BUT, these days, these times are now in response to load and load shedding and so the 'moaning' is unpredictable and therefore difficult to confirm.
One interesting humorous aside was that a certain brand of oven had an oven clock that 'spun' at 17 or 21 times the correct speed for the duration of the signal

fletty