Wiring a 3 phase motor

[graduate_owner]

Hi all,
My Viceroy Sharpedge has a Hoover brand 3 phase motor, and the information plate gives a range of voltages from 220 to 415. There are 4 terminals, labelled 1 - 4. The three supply phases connect to terminals 1, 2 and 3, while terminal 4 has 2 wires going into the motor. I am familiar with the usual 6 terminals for star / delta but not with this.

Does anyone know anything about this sort of connection? Can I just connect my inverter drive (output 220V 3 phase) directly to this motor?
Any ideas guys?

K

 

[ChaiLatte]

Are you 100% positive of terminal 4 only having _two_ wires? If terminal 4 were the star point, it would have three wires.

If the motor data plate gives options for low and high voltage, the configuration will be done in the terminal box and will not require the motor to be dismantled.

Take some good, clear, close up photos of the terminal box.

If there is a nut holding down the wires on terminal 4, remove it, remove the first wire, remove the second wire and see if a third one is hiding at the bottom.

 

[Spectric]

There should be a label in the terminal housing showing the connections for star / delta connections.

 

[Sideways]

There should be a label in the terminal housing showing the connections for star / delta connections.

Yes, sometimes a label, sometimes the diagram is cast into the inside surface of the terminal box lid.
Either way, could you post up a bunch of pictures for us please. Include the motor nameplate, the terminals and any diagram. Take from a couple of different angles so that we can picture it in 3d in case one wire passes behind another anywhere.

It's unlikely but there are some less common configurations out there like the Dahlander wound motor which allows switching of the motor speed.
https://en.wikipedia.org/wiki/Dahlander_pole_changing_motor
Your photos may just trigger someone's memory.

4 terminals could be a fixed star wound motor with just 3 coil ends and the star point brought out
BUT
If your name plate shows both 415 and 220v options, then that implies that the motor can be hooked up in either star or delta, not hard wired in star.

Are there any jumpers / brass links such as you would expect to find to configure star / delta ?

If you have a multimeter.
Make a simple matrix 5 on each side.
Label the rows and columns 1, 2, 3, 4a, 4b to match the three terminals and the two wires going to the 4th terminal.
Use the meter on ohms to measure all the resistances 1 to 2, 1 to 3, 2 to 3, 1 to 4a, 4a to 4b etc etc and fill in the matrix for us. We're less bothered about absolute accuracy, it's more to look for any pattern that may help explain the windings.

Don't connect a motor you don't understand up to a vfd. That's not smart. You can't even be sure how to program the VFD until you know how the motor is wired.

 

[ChaiLatte]

It's unlikely but there are some less common configurations out there like the Dahlander wound motor which allows switching of the motor speed.

The machine is a standard Viceroy Sharpedge, removed as a working machine from someone else's workshop. It does not have a 2-speed motor.

A four terminal connection box was standard before the more modern six terminal one with links was introduced. It did not have links/bars.

A four terminal one can be used for both star and delta, it just involves moving wires around on the posts, rather than the modern approach of leaving the wires on the posts and moving the links around. The modern one may have been introduced for ergonomics/time saving/de-skilling reasons.

 

[graduate_owner]

Thanks guys. I will take some photographs and make some resistance measurements.

K

 

[Spectric]

Maybe this will help

The one on the left is single phase using Blue wires and that on the right is three phase using the brown wires. Do you have those colors ?

 

[ChaiLatte]

Maybe this will help

The left side is irrelevant as he has a three phase motor. He is trying to work out how to connect the motor for 230v three phase as opposed to 415v three phase (in the diagram the bit we are interested in would be below the LLL). The right hand diagram has nothing to say on that issue as it relates to the contactor at the top of the figures, not the motor at the bottom.

Note that the 'remove link' part refers to terminals 5 & 7 of the contactor, towards the top of the figure. The position of the writing near to the motor is unfortunate.

 

[graduate_owner]

I agree with Chailatte, it's not quite what I am after but thank you Spectric for taking the time to post that anyway - and it might come in handy in the future so I will copy it.

K

 

[graduate_owner]

Hi again all,
I have now checked the details on the motor plate. It reads -
Volts 220/240/380/440
Amps 1.4/.8
HP 1/4

There are indeed 3 cables connected to terminal 4, black, white and yellow (the black one was hiding under the others).

So, any ideas on whether I can connect it as it is to a VFD inverter? I would bypass the original switchgear.

K

 

[ChaiLatte]

So, any ideas on whether I can connect it as it is to a VFD inverter? I would bypass the original switchgear.

As it is, you could connect it directly to a VFD that has 415v output. 230v single phase input and 415v three phase output VFDs are available from China, via Amazon.

The secret code to find one is "XSY AT4".

https://www.amazon.co.uk/AT4-2200X-Universal-Variable-Frequency-Converter/dp/B07VB4P719

If you wish to connect it to a more widely available 230v single phase input and 230v three phase output VFD, you need to reconfigure the motor into delta (mesh).

Connecting it as is to a "low voltage" three phase VFD will not hurt the motor or VFD; it just won't work very well.

 

[Sideways]

To second the advice above,

Provided you move the wires coming from inside the motor onto the terminals in a different (mesh or delta) arrangement, you will be able to operate it at full power from a 240V single to three phase VFD.

 

[ChaiLatte]

There are 3 cables connected to terminal 4, black, white and yellow

We are nearly there in showing you how to reconfgure to delta for the low voltage 3-phase.

Please list what colour is connected to each of terminals 1, 2 & 3.

If you need to remove the wires to identify the colours, do so one at a time and replace the wire on the terminal it came off before touching the next one.

Maybe a hypothetical example will assist. Let us say we have orange on 1, purple on 2 and green on 3 and again orange, purple and green on terminal 4 (the star point)*. To wire as delta, put terminal 4's orange onto terminal 2 (on top of the purple already there). Put terminal 4's purple onto terminal 3 (on top of the green that is already there). Put terminal 4's green onto terminal 2 (on top of the orange already there). Terminal 4 will be empty (pilot's strike or COVID or something like that). Connect incoming phase wires from VFD to terminals 1, 2 & 3 (so each of terminals 1, 2 & 3 will have three wires total on it).

This is a 'teach a man to fish' exercise - once you know how to do it, you will be sorted for life.

Any sensible future person should verify how the motor is connected, just like you are doing here, but it would not hurt to put a piece of paper inside the connection box before you put back the lid saying 'connected in delta' (or write in marker pen inside the lid).

* this is my get out of jail disclaimer asterisk. We are assuming that orange at one end is also orange at the other end. If there is any doubt on this point, verify with a continuity meter.

 

[niall Y]

Here is a naive question about three phase, but I'm going to ask it anyway, What is the difference between 415v three phase and 230v three phase.? I've always understood that 230/240v AC supplied as three separate phases ,gives you 415v AC.

 

[graduate_owner]

Sideways - t
he trouble is I don't know which wires to change. I have just the 4 terminals, 3 incoming from the supply, labelled 1, 2 and 3, and terminal 4 has 3 wires, black, white and yellow. There is no indication on the motor regarding how these 6 wires are connected.

K

 

[ChaiLatte]

What is the difference between 415v three phase and 230v three phase? I've always understood that 230/240v AC supplied as three separate phases, gives you 415v AC.

In the place you have written "230/240v AC" that is a phase-to-neutral value/level/reading/voltage. And as you say, if you put three of these 120 degrees apart, you obtain a phase-to-phase value of 415v (240 x sqrt(3) = 415).

To obtain 240v 3-phase from the mains, you would need a phase-to-neutral voltage of 240/sqrt(3) = 138v. The closest to that is in the US, where they have 120v phase-to-neutral, hence 208v phase-to-phase three phase.

Most voltages have a roughly 10% tolerance on them. This is why Europe has standardised on 230v nominal because the UK 240v and continental 220v are both within 10% of that figure, meaning everyone is harmonised but no-one actually needs to do anything different.

If you are using a magic box of electronic loveliness (a VFD) to produce your three phase, i.e. not directly from the mains, things are slightly different. A standard VFD takes 240v single phase input and rectifies it to DC (roughly 340v, which is 240 x sqrt(2)). The electronics then chop up that DC voltage to produce whatever output you want. In 90% of cases, it will be 240v phase-to-phase.

Your brushless-motored cordless drill is effectively a three phase motor. The control box in that takes the DC voltage from the battery and chops it up in exactly the same way as a VFD.

The AT4 VFDs have additional circuitry which effectively doubles the input voltage, so they can use 240v single phase in and give 415v three phase out.

 

[graduate_owner]

Thank you Chailatte, I will take some resistance measurements.

K

 

[ChaiLatte]

I will take some resistance measurements.

In order not to confuse things, you need to disconnect the incoming supply wires before measuring anything. You do not need resistance as such, only continuity. Every wire on terminal 4 should have continuity with one and only one of terminals 1, 2, 3.

---

...I have just the 4 terminals, 3 incoming from the supply, labelled 1, 2 and 3

Remove the incoming wires from the motor. Underneath them you should find the other ends of the three wires that are on terminal 4.

A three phase motor has three coils in it, so has six wires that "belong" to the motor. These six wires will disappear into the motory abyss. They are the ones you need to locate. The three wires feeding the power into the motor are not relevant to us just now.

It might help to look at some Google images of three phase motor connections. It will give you a flavour of what you are seeking in your own one.

It was said above that photos would help resolve this much more speedily. That advice still stands.

 

[Sideways]

Sideways - t
he trouble is I don't know which wires to change. I have just the 4 terminals, 3 incoming from the supply, labelled 1, 2 and 3, and terminal 4 has 3 wires, black, white and yellow. There is no indication on the motor regarding how these 6 wires are connected.

K

This is the image of what you are trying to achieve.
The 3 zig zag "resistors" represent the three coils inside the motor.
Your objective is to reconnect them into a triangle.

If you were to remove the mains cable from the motor terminal box, you would be left with a total of 6 wires. Two black, two white and two yellow. Ot doesn't matter if the actual colours of these wires are different, there will be 2 each of 3 different colours.
Each pair of wires that share a colour are the two ends of an individual coil.
You can use a multimeter on ohms or continuity to prove that.
You could even prove it using a simple battery and bulb circuit.

You want to reorganise the wires in the terminal box (electrically) into a triangle just like above.
It doesn't matter which of the three coils you call black, which is white and which is yellow.
The three points of the triangle are your terminals 1, 2 and 3.
Again, it doesn't matter which point is your t1, t2 or t3.
When you have rewired the motor, terminal 4 will have no wires connected to it.That is correct.

Once you have done this, you can connect the supply cable from your VFD into the motor terminal box. You should be using a 4 core cable for this with the colours
Brown - connect this to Terminal 1 along with the two motor wires that are already there
Black - connect this to Terminal 2 along with the two wires that are already there
Grey - connect this to Terminal 3 along with ....
Yellow / Green - connect this to an earth screw that goes directly into the motor body. There is usually one of these in the terminal box, but if not, crimp a ring terminal on the end to fit around a bolt somewhere on the motor body.
These are the standard colours of a "3 phases plus earth" cable that you can buy from many electricians counters.
You don't need a neutral in this cable, so no blue wire.

It is genuinely that easy.
But my next, slightly worried, question is : have you ever wired or programmed a VFD before or is this your first rodeo ?

 

[ChaiLatte]

...have you ever wired or programmed a VFD before or is this your first rodeo?

The Eaton DE11 VFDs are about the closest you would get to a no-programming-required device. For a Sharpedge, which only needs two settings, on and off, one might do well.

https://inverterdrive.com/group/AC-Inverter-Drives-230V/Eaton-DE11-124D3FN-N20N/