Is there a wiring diagram showing the wiring for delta/star on the inside of the terminal cover?

It is possible to misinterpret your description above, so you might have to be more clear in the way you describe the connections.

In particular, you need to list clearly the relationship between the six wires.

I _think_ you are saying: red (A) and brown are connected; yellow (B) and black are connected; blue (C) and white are connected. However, my (or anyone else's) thinking is a particularly bad way to proceed. Certainty and clarity is required.

If this is the case, and you connect brown to terminal A (red), as you appear to be saying above, you are just connecting the two ends of the same coil together. No harm will come by doing so, but the motor will not work.

You have the delta triangle on the data plate. Each side of the triangle is one of the three coils. Each vertex of the triangle can be labelled sequentially A, B, C. So the 'start' of the first coil goes to 'A'. The 'end' of the first coil goes to 'B'. The start of the second coil goes to 'B'. The end of the second coil goes to 'C'. The start of the third coil goes to 'C'. The end of the third coil goes to 'A'. One each of the incoming phases goes to A, B, C.

Your Plan will work, but there are some issues.

1/ The motor must be connected directly to the output of the VFD (inverter) wihout any switches, fuses etc.
2/ You need to provide an enclosure for the VFD.
3/ You need to provide Stop, Start and FWD/REV switches / controls. It may be possible to repurpose the existing controls depending on what they are. For anything other than your own hobby use it should also have a emergency stop and isolator to comply with safety regulations. You can maim yourself but not employees or members of the public.
4/ You could leave the VFD set at 50HZ but that is wasting a significant capability. Adding a simple potentiometer will give you variable speed control. You could set the maximum frequency to 60Hz and get 20% higher speed in each range.
5/ You don't need a NVR, the VFD can be set up so it will not automatically start when power is applied.

I agree with DC31K, with a branded VFD there is no need to derate it or buy a larger VFD than the motor rating. It actually has some disadvantages.

Robert

I fitted my Fobco drill with a three phase motor and VFD years ago.

My advice:

Leave the belt on it’s slowest speed and incorporate a speed pot in a new control unit.

Forget the existing fwd/reverse switch and, if you need reverse, include a suitable switch on the control panel.

Wire the input to the VFD via a fused spur/fcu so it can’t be unplugged.

I’ve never seen a commercial machine that didn’t have a NVR on the single phase input to a vfd

if you connect the input wires direct to the drive the pins are going to be possibly live for 30 seconds or so when unplugged

we can all do what we want with electricity in our own workshops but you do have to think about others..

If the VFD / machine is connected to a fixed outlet, i.e no plug & socket, the outlet MUST have a isolation switch. Ideally this should be able to be locked in the off position with a padlock.

Robert.

Edited By Robert Atkinson 2 on 20/05/2023 09:03:38

My understanding of ‘NVR’ is “no volts release” simply meaning that the drive will not restart, after a power interruption, without intended input from the operator. Electrocution risk is taken care of by other means and an NVR switch only safeguards against physical injury.

My point about a NVR switch in this application is to stop the real risk of electrocution if someone unplugged the 3 pin plug wired directly to a drive.and touched the pins within the discharge time.

all drives make note of this in the manuals..( i have been shocked too by this)

in my day job i repair many machines with drives and have NEVER seen a machine without a NVR device (meaning if the power supply is removed the main machine is isolated from the plug). fitted to prevent back flow to the plug

NVR in this application isn’t to do with the machine restarting if power is restored

bigger machines with 3 phase supplies wired into idolaters with conduit still have a contactor to disconnect the supply from the machine control circuits if the supply goes down

David

Fundamentally the motor coils all have to be the same way round. If one is reversed relative to the other pair the motor doesn't run as smoothly or efficiently.

If you still have the coloured sleeves on them then follow the diagram posted earlier.

If you don't have the colours but haven't yet mixed up the wires follow the same sequence. Star point wires are all at one end of a motor coil and the free ends are the power input. So in delta connection carries one of the old power input connections and one ex star point connection from another coil.

If you have mixed the connectors up there is a way of measuring current through the coils to figure out if one is the wrong way round. Fortunately only one can be wrong relative to the other too so it's not silly difficult. I have it written down somewhere so can post if need be.

Clive

Edited By Clive Foster on 21/05/2023 14:18:43

I can also recommend “Inverter Drive Supermarket”

No need to buy an inverter one size larger than than the motor rating.

Inverter should be installed in an enclosure (would not pass any electrical inspection if this is not done as swarf fingers etc can touch the live 3phase terminals).

To avoid the cost and hassle of an enclosure I bought a IP66 rated inverter when I converted my Bridgeport mill and Colchester bantam These inverters are slightly more expensive but as they and waterproof you don’t need the enclosure. Also no need to worry about swarf or coolant getting on the inverter.

Use screened cable and correct glands between the inverter and motor (SY cable)

If your not competent with electrics get someone who is to wire it up for you