Posted by Absolute Beginner on 18/10/2018 21:51:19:.
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Having established, and understood by some, that the convertor changes 240V single phase to 415V three phase in plug and play mode and that the convertor (5HP) is underpowered for my lathe Colchester Student 2500 2.2KW + 3HP on start up.
It was suggested to me that I insert a soft starter between the Converter and motor supply.
So I cant see why the convertor would not be able to power the motor as the soft starter would limit the inrush current on start up, and take the strain away from the convertor
Anybody have any constructive thoughts???
I Cant see why it wouldn't be an OK solution!!!
Gary
To be constructive more information about the Converter is needed. It feels as if we're on that part of the map that says 'Here be Dragons'.
It's easier to identify what the dragons might be than to prove they don't exist!
- Unless the nature of an inverters output circuitry is understood, it's not a good idea to mess with the output side. Three problems:
- the VFD's output devices might be sensitive to anything other than a motor load, especially hot-plugging, or unexpected capacitance & inductance; or
- the VFD waveform might not suit a downstream device expecting pure AC; and
- the controller may adapt to a motor by measuring how the motor loads the output, and be upset by something unexpected in circuit.
- There are several different types of soft starter. They work in very different ways, and who knows how compatible they might be with the output of a VFD without reading the manuals and/or asking the maker? Certainly the inductive type of soft starter is very likely to cause trouble on the output of a VFD, though it would probably be fine on the input AC side. Conversely an electronic soft starter might be OK on the output, and not acceptable on the input.
If it's not covered by the Manual, proceed at your own risk.
Before trying a soft starter, I'd want to eliminate other possibilities first. For example what Error Code does the converter throw when it fails? It might show:
- A sag in the mains input voltage caused by the switch on surge. This is a suspect if the workshop happens to be on the end of a long spur. The cure is a fatter cable.
- Overload on the output side. This might be cured by slowing the rate at which the VFD ramps up the frequency. How this is done may not be obvious – searching my cheapo VFD manual for 'soft start' reveals nothing, but in fact the VFD can be configured to achieve it. ( It's under 'Frequency Control' ).
- Most Manuals have a Troubleshooting Section that might suggest answers to particular fault code.
General comment on VFD Manuals. I find they usually have a straightforward 'get you started' section that's probably plenty good enough for most people in most cases. Unfortunately, if you have a deeper requirement like this one, the easy bit is followed by a dense mass of terse engineering jargon written for experts. Very likely that's where the answer is, unless the VFD seller can help.
I'm often in favour of experimenting with this sort of problem to see if a solution works. Given the cost of getting it wrong, I'm nervous of recommending that while there's hope of getting an authoritative answer. That said, putting a Reactor type soft starter on the input AC is unlikely to damage anything – worth a try?
Dave
Edit pesky smileys…
Edited By SillyOldDuffer on 19/10/2018 11:23:21