You can only go so far, if the screw is worn it will be in the middle of its travel. But compensating for nut wear is doable.
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Agroshield
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Generally, the only reason you set the number of poles in the VFD is so it displays the motor RPM correctly.
Setting the number of poles changes absolutely nothing that comes down the wires from the VFD.
RPM display is very much an optional feature, not fundamental to how the VFD operates when driving a motor of either type.
The lockout is recommended just so you do not try to change speeds when the VFD's output is high. Two VFDs are not required.
Brad93
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If you say so.
Agroshield
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It is easy enough to convince yourself if you are sceptical. Set the VFD for 2 pole and put a sillyscope on the output. Take a picture of it. Change the VFD to 4 pole and repeat the process. Compare pictures.
Brad93
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Well i'm guessing the OP isn't going to be using an absolutely bog standard basic VFD let's call it a 'Dumb' VFD, but will be using a chinese unit which have programmable features.
How do you deal with Motor Amperage?
You cannot input two amperage settings for the two different sets of windings, how do you tell the VFD that, without it thinking you're over-current, or it not applying over current protection to the motor when using the lower amperage set of windings.
And what about VFD's that require tuning?
I'm not saying it cannot be done. But no manufacturer will warranty a motor or a vfd used outside of the usage outlined in the manual. And i don't think i've seen a manual from Parker, ABB or mitsubishi which says you can use a vfd on a two speed motor and have a switch between two sets of windings
Maker
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As far as I know, the current setting is really just an "alarm", the drive will shut off if it detects the current going over the threshold to protect the motor, not setting it is no more dangerous than plugging a motor directly into the mains.
I have a socket on my Mitsubishi inverter so I can swap between the lathe (2kW) and drill (0.25kW I believe), I don't change any settings and I've never had a problem. If something goes wrong with the drill motor, the drive will happily cook it (Provided the current on all three phases stays the same, it detects it and shuts off if there's a big phase imbalance), but I'm not worried, if the motor tries to draw too much current it's probably shagged already.
I've only ever ran 4 pole motors off of it (And I assume the parameter is set to 4 pole) so I can't say for certain, but I'm sure it would run a 2, 6 or 8 pole motor without an issue.
Lewis_RX8
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Ah yes I also had the two-speed motor one, It is wired in 16A 240v supply to a Single phase 240 to Three Phase 440v Chinese VFD. The two-way switching is done using the original Colchester switching gear which is wired in-between the VFD and the lathe motor to set either low or high speed.
However I also now have a potentiometer wired into the VFD next to an RPM readout so I can vary frequency to change speed which is a lot handier most of the time so mainly use that but two speed setting is handy every now and again.
I haven't had any issues yet with the VFD running a two-speed motor? ,
Heres the VFD , It is also installed with a EMC filter to try to protect the older motor that wasn't designed for use with a VFD.
Lewis_RX8
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Are you ready for a go with the ainjest ?
It's a real game changer , I run out of bottle at 1000 rpm .
Just make sure the stop is set securely , safety squint set to max and let her rip !
I will have to try it sometime, All my threading has been calm and coordinated taking my time lol. Will need to put the trust in the machine seeing that bounding along towards the chuck at high RPM
@Lewis_RX8 looking to buy the same vfd as you can’t seem to find a manual anywhere I want to see if the vfd can be wired to a external braking resistor cheers
Agroshield
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Page 6 for the brake resistor (though it does not list a 220v in 7.5kW device in the table).
Lewis_RX8
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I see looks like @argosheild may have on there I did not fit a braking resistor to mine so don't think I am much use but will have a hunt for what paperwork came with it and see if there's anything useful.
