Static phase converter plug wiring

[Stuart Davies 3Participant @stuartdavies3]

Dear all,

Just wondering if anyone has some experience to share with wiring a 3 phase plug to be used in the output of a static phase converter?
I have bought a static phase converter, and was supplied with a 5 pin plug. My raglan lathe has 3 wires coming out of it, red yellow and black plus earth. On the wiring diagram these are labelled A,B and C. I called the supplier of the converter to ask if ABC should be connected to L1 L2 and L3 in the plug, and they were rather unhelpful, saying that a qualified electrician needed to be called. Yawn. So I got a local electrician to have a look and they seemed to know less than I do…What’s wrong with this country?!

As I understand the output from a static phase converter has two ‘good’ phases and a third phantom phase-does it matter which phases from the motor are connected to the L1 L2 L3 ? As I understand L3 is the phantom phase.

Help please!

Thanks

[Stuart Davies 3Participant @stuartdavies3]

[Anonymous]

Offhand I can’t see it makes any difference to the motor as to which wire is connected to the ‘phantom’ phase from the converter.

 

Ah, but your local electrican was ‘certified’, possibly in at least two of the senses of the word. As I’m sure you’re aware the ‘Part P’ farrago was justified partly on the number of fires caused by ‘amateur’ electrical work. A much more interesting question would have been how many fires are caused by ‘professional’ electrical work.

 

Regards,

 

Andrew

[John HaineParticipant @johnhaine32865]

Do you mean a vfd?

Normally you would expect 3 phase wires plus neutral (for a star configuration). There would then be an earth which should connect to mains earth but not neutral. Order of connection shouldn’t matter but you may need to swap 2 wires if the motor goes the wrong way.

[Stuart Davies 3Participant @stuartdavies3]

Thanks guys, I dont think I mean a VFD- isnt that an inverter with a variable frequency? My converter frequency is fixed at 50 HZ so there is no variable speed (except of course from the wonderfully simple Raglan variable speed pulleys of which i’m proud )

The neutral on the wiring diagram supplied with the lathe is not connected to anything-just a bunch of wires coming out of the motor connected to the motor terminal box but with no wire out of the motor terminal box.

Im inclined to connect ABC from the machine to L1L2L3 in the 5 pin plug and give it a go but as the converter cost over £300 im a little reluctuant…

 

Although the different legs on the converter have different outputs, surely the motor legs are identical? The open circuit voltages on the converter are 400v between L1 and L3; 400v or 560v between L2 and L3 and no volts or 160v between L1 and L2, but these do not relate to earth as they would on mains 3 phase electricity.Incidentally my local electrician first thought it was a single phase motor. *Grins*

[Michael Taylor 3Participant @michaeltaylor3]

Hello, I’m a newcomer to this forum but I hope my own experience might be helpful.

 

John Haine raises a very good point. The use of a variable frequency device requires a very different approach to an older style static converter. My old style static converters have a 415V output so the contactor in the machine starter must be 415V and be wired between the two “good” phases to ensure reliable operation.

 

Some of my VFD converters have 240V 3 phase output so the motor wiring must be changed to delta. I have one VFD which has 240V input and 415V 3 phase output. I use this on a motor where the star point is not accessible and delta connection is not possible

 

None of my converters supply a neutral in the output.

 

Stuart, could you post details of your converter so that we all know what we are dealing with?

 

Regards

Mike

 

 Oops, I’ve been gazing at this for so long that Stuart beat me to it, sorry.

 

 

Edited By Michael Taylor 3 on 29/01/2012 12:40:34

[martin perman 1Participant @martinperman1]

I have a seimens single/three phase convertor with variable frequency for speed control which is 230VAC 1PH in to 230VAC 3PH out earth but no neutral.

 

Martin P

[mgnbukParticipant @mgnbuk]

As I understand the output from a static phase converter has two ‘good’
phases and a third phantom phase-does it matter which phases from the
motor are connected to the L1 L2 L3 ? As I understand L3 is the phantom
phase.

I have a Clarke PC20 static conveter. The manual for that device states that L1 and L3 are the “good” phases to be used for contactors etc. This device has no neutral connection (4 pin socket). If you have no requirement for a contactor (which would need to be 415V), then connect the 3 motor phases to L1-L2-L3 in any order. If the motor runs backwards, reverse any two wires.

 

Normal “old” colours were red-yellow-blue for the 3 phases, though – black was neutral. Are you sure you have a 415V 3 phase motor ? Maybe open the terminal box to check that the black wire is actually connected to a phase ?

 

The manual for the Clarke PC20 can be downloaded from here :

 

http://www.machinemart.co.uk/download/PC20-40-60-PHASE-CONVERTERS.pdf

 

Regards,

 

Nigel B.

[Stuart Davies 3Participant @stuartdavies3]

thanks all again, my motor is dual voltage, that is it can be wired for 220 or any voltage between 380 and 415. I have a picture of the terminal box and a copy of the wiring diagram-will try to attach them to this post. I dont believe I have a contactor switch on the machine-the controls for the motor and suds pump are drum type santon switches and dont seem to have any extra circuitry for an electricly assisted switch. It seems from the literature supplied with the converter that L2 is the ‘duff’ phase as it shouldnt be connected to any contactor switches etc (as I say I dont believe I have any). I will say that this unit was not from machinemart.

L1 is the domestic single phase and should be connected to any machine light or other item requiring single phase, and connected to neutral on the converter-there are no such items to worry about on this machine.

Thanks again folks-anyone who can look at the photo/wiring diagram and give any more info would be greatly appreciated.

 

[Stuart Davies 3Participant @stuartdavies3]

http://www.model-engineer.co.uk/albums/member_album.asp?a=19403

 

Photos posted here

[Sub MandrelParticipant @submandrel]

Stuart

 

You have already twigged that a dual voltage motor needs to be wired correctly for your converter.

 

If the converter gives a full 415V then make sure you have it wired in star mode – that way the 415V is always shared across two coils in series.

 

Neil

[Author]

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