Member postings for Simon_F3

Robert, you were absolutely right! I decided to delve deeper into the manual and it turns out there would originally have been a couple of jumpers to connect the control circuit to the input power. These had been removed to enable the alarm system to stay live in the event of a trip, and though I disconnected all extraneous wiring I hadn't twigged that I needed to bridge a couple of connections.

So using 420V single phase it powers up and gives the 'right' information on the screen. I'll try it with a motor under no load in the next few days.

Thanks again for the tip, potentially saved the unit from the skip!

Well, to close this out it seems that this model of VFD does not work with a single phase input. I painstakingly went through increasing voltages to try to condition the capacitors, but at 415V single phase there was still no sign of life!

Many thanks again for the help - much appreciated.

Yes

Hi All, thanks for the various bits of information. I should have thought a bit more carefully about the operation of a VFD really, as it's fairly obvious that a single phase input could be rectified to DC, albeit with the potential to retain a few ripples.

I think I'll set it up to start gently and give the capacitors a chance to recover, though it's probably possible to replace these if absolutely necessary. I have a very large autotransformer that can be persuaded to give quite a range of voltages so I'll start small and work my way up. At the end of the day this was a freebie so it's not a calamity if it doesn't work, but it would be a real bonus if it does as it would mean i don't need to run an idler motor.

For a power supply my electrician is about to hook up a 40A radial circuit from the RCD-enabled distribution board, which will do for checking this out. This supply is ultimately intended for my rotary phase converter, but that is another project entirely (I may post on that elsewhere, as it's been an interesting journey of discovery!).

The VFD is inside a steel cabinet with specific fuses for the 3~ inputs on RST, so there is an additional layer of protection for the wiring and device there. I think I'll just give it a go with single phase to terminals R and S at incremental voltages from 12V to 415V and see how I get on.

Many thanks again for the various bits of information, Simon.

Hi all,

I obtained a Mitsubishi 5.5kW VFD during a work clear-out, and I am trying to work out whether it would accept a single phase input or not. It was previously used with 415V 3 phase supply in a factory environment, but the [generic] manual I have found also gives wiring instructions for single phase input (i.e. use terminals R and S for 1~, rather than R, S, T for 3~).

Link to manual - this should go to the right page...

As this is a 400V model I would assume a single phase input would not typically be used, but I have an autotransformer in my rotary phase converter to get 415V single phase, and if I could run the VFD directly from the transformer it would simplify the set-up a bit!

The VFD is a Mitsubishi FR-A140-5.5K-ER from about 1994, I believe.

Any advice gratefully received - I guess at worst I could connect it to the single phase 415V supply and see whether it powers up! It clearly would expect to see 415V between phases, so a single phase input would not exceed this...

Many thanks in advance