How to wire up 3 phase motor and 3 phase converter?

[ell81Participant @ell81]

So, I have a 3 phase motor, dual voltage. It has come with no cable for it. So I obviously need to wire one in.

It will be powered by single phase power, converted by a single to 3 phase converter.

I am wondering which wires to use for the cable? Is there an amperage rating I need for the wires?

Ideally I want to make the lead on the 3 phase motor have a male socket on it, (will this be 4 or 5 pin?)

and have the 3 phase lead from the converter have a female socket on it.

Will I need just the 4 wires for the 3 phase lead coming from the converter and the lead on the motor?

This way I can unplug the motor and use the converter on a different motor.

Here is a pic of what I mean:

 

Here are the pics of the motor badge, the wiring diagram for it, and the converter connections:

[Robert Atkinson 2Participant @robertatkinson2]

The wire size is set by the VFD output current rating / input fuse rating. While 1mm2 woube adequate I suggest using 1.5mm.
For specific cable types consider “SY”  protected flexible cable. One supplier I’ve used is TLC
https://www.tlc-direct.co.uk/Main_Index/Cable_Index/Multi-Flex/index.html?
But any local electrical supplier should have it. You want 1.5mm2 four core (3 phases and protective earth).
It is generally considered bad practice to put connectors in the output of VFCs. If you must then ideally yo should use a metal bodied connector like a Harting HAN series to reduce interference. A more available choice is a 3P+PE 16A red IEC 60309 “commando” plug and socket e.g.
https://www.tlc-direct.co.uk/Products/MKK9007RED.html

Don’t un-plug with power on, even with motor stopped.

Robert.

[SillyOldDufferModerator @sillyoldduffer]

What Robert said!  I’d go further than “It is generally considered bad practice to put connectors in the output of VFCs.” and positively recommend NOT using connectors and NOT swapping one VFD between several motors.

The VFD isn’t a magic black-box producing a sine wave like wot comes out of a mains socket.  Rather the electronics simulate a sine wave by pulse width modulating a DC signal, and pulses do not behave like sine waves!   No problem with pulses when a VFD is correctly connected to the motor, because the motor windings smooth them out.   But, red-alert, if a VFD phase is disconnected whilst power is applied, the motor winding can behave like a car-ignition coil, and several thousand volts appear on the end.   The operator might get a nasty shock, but more likely the high voltage will punch holes through the motor’s insulation, and/or the VFD’s electronics, turning them into toast.

These days VFDs often come with factory defaults allowing the unit to drive almost any motor out-of-the-box, hurrah!   However, an advanced user might well chose to alter the defaults to suit his a particular motor:  soft-start, frequencies, and a few hundred other tweaks!   And some VFDs automatically tune themselves to suit the motor, and get confused if a different one is plugged in!   Auto tuning used to be reserved for top-end VFDs, but it’s filtering down into cheaper units.   Either way,  not clever to share a tuned VFD between different motors without resetting it first.

Sharing a VFD is a bodge that works perfectly until something goes wrong!  Many ways it can go bad, including the operator absent-mindedly pulling the plug with power on, or the contact pins wearing or corroding, or a wire coming loose.   So best practice is to dedicate a separate VFD to the motor and hardwire it in.   This suits another best practice rule, the 3-phase wiring should be as short as possible, less than a metre, and certainly not running round the workshop.

Another misunderstanding can cause trouble!  Most VFDs are components, meant to be protected inside another box, ideally earthed metal.   Partly to secure the wiring and protect the operator from exposed terminals but also very important to keep swarf, dirt and condensation out of the electronics.

Similarly, though VFDs can be controlled with the supplied keypad, these are only intended for setting up – they aren’t robust!   Normal operation calls for a remote speed control pot, forward/stop/reverse switch and emergency stop.  These controls can be mounted in the box protecting the VFD, but it’s usually more convenient to have the VFD near the motor (short wires are best), with the controls handy for the operator.   Control wiring can be any length.

These problems all relate to cost cutting measures.  Up to the owner to balance the risk, but, as always, “too cheap” is liable to become “unfit for purpose”.

A minor detail next.  The photo shows the motor terminals are currently strapped for STAR aka Y connection, ie 400V  rather than 230.   The straps need to be moved to the delta Δ configuration.  In the pic below, the existing Y connection is high-lighted in red,  you want to move the straps into the green position (delta), as per the diagram inside the lid.

Dave

[noel shelleyParticipant @noelshelley55608]

In this day and age the most common way to run a 3phase motor from single phase is with an INVERTER or VFD, it is NOT the only way, there are CONVERTERS that will raise the voltage to 415V and artificially make the 3rd phase. The OP uses the term CONVERTER, though the picture appears to show an INVERTER, 2 very different types of equipment that require very different methods Etc. The VFD needs in most cases a dual voltage motor set to Delta 220V where as the Converter will use a star connected 415V motor. As for plugs sockets Robert and Dave have covered various points.

If the OP has little knowledge of such things and is dealing with lethal voltages then the best advice is to seek the help of a competent electrician with experience in this field to do the work. Noel.

[OldironParticipant @oldiron]

In the hand drawn layout picture it shows a socket attached to the motor. This should be a plug. Never use a male/male lead for connections.  Although I agree with Robert that its not really good practice to have a connector between units.  Also Noels point that this is really a job for a competent electrician is correct.

[ZanParticipant @zan]

No no no no.  One vdf one motor

for me that’s Myford s7b, Bridgeport, Colchester student and  fobco pillar drill.

4 motors 4 inverters  they all need setting up to match the individual motor  ie current, max and min speed and a plethora of other settings obtainable in the manual ( can’t remember them all, years since I set up the last one )

Far far too dangerous to consider swapping things about, far too much risk of a smoking body laying on the workshop floor………

[Robert Atkinson 2Participant @robertatkinson2]

Well spotted Old Iron. I didn’t look at the sketch. You can easily get male or female 60309 connectors in cable or fixed mounting.
I agree entirely with SOD and Noel but thought I’d just answer the question and not have to get my flame proof overalls on 🙂

[EmgeeParticipant @emgee]

One thing not mentioned so far is connecting the cable screen to the cpc at the VFD, difficult to do if using any type of insulated plug/socket arrangement.

 

Emgee

 

[Author]

Posts