3 Ph motor wiring help

[1NRO]

This machine came to me with the wiring off the motor and I'm at the stage where it's to do but I know not what I'm doing! Can anyone help?

The photo I'm trying to upload is too big apparently and I'm at a loss as to resizing on my phone.

I have three terminals on the motor, labelled A1, B1 and C1. The wire in question has red, blue, white and green cores.

 

[1NRO]

Hopefully s picture

 

[sunnybob]

Any chance of a picture of the identification plate on the side of the motor? You can never have too much information. 8)

 

[MikeK]

Yes, please send more pictures of the data plate on the motor. This will identify the voltage, phase configuration, and input power requirement.

However, just from the information provided, it appears that the motor is a 3-phase delta configuration and does not need a neutral connection. Assuming this is correct, A1, B1, and C1 should be the three 400V (phase to phase) terminals for the motor.

Do you have 3-phase distribution where you want to put the equipment?

 

[Argus]

Based on what you've just said, the only valid advice is to hand it over to a qualified practitioner, and ask him to:

1 - Test the electrical safety of the motor.
2 - Check the electrical safety of your incoming supply and the interconnecting wiring.
3 - If the above is safe, connect it, adjust it for the correct rotational direction (if it's important), record the voltage, running current and sign it off.

3 phase power wrongly handled can cause serious injury or fire. If you are unqualified and If you do it yourself, any insurance firm will walk away. It's a bit like an amateur doing their own repairs on a live gas main.

 

[1NRO]

It's only this connection, the rest is as ran previously. I understand you safety stance but I'm skint enough without employing an electrician at this stage.

Hopefully a motor plate pic.

 

[guineafowl21]

With only three single connections, that will be configured in star and will require 400V 3 phase unless converted.

Chuck away that old colour wiring - get yourself a length of 4-core 2.5mm2 SY cable which will be tough and looks the part.

L1 - brown -> A1
L2 - black - >B1
L3 - grey -> C1
Earth - green/yellow. Bond it securely to motor frame. Make sure other junctions, eg start switch, and also bonded to earth. Also connect the armour weave to earth.

If it runs backwards, swap any two connections around (except the earth!)

Before you go any further, can we have a pic/description of your circuit from distribution board to motor? If there’s a socket, it should really be protected by an RCD. For overcurrent in the cables, a 16A 3P breaker should suffice. Make sure there’s a dedicated NVR switch before the motor, set to the FL amps value.

Others on here are correct, you should really have the motor meggered before hooking up.

 

[1NRO]

The machine is at a different workshop to where I have three phase, I called by a snapped a pic you of the board/breaker. There's just a socket at the other end, I just swap over for different machines. The machine still has its original switch, I'll be looking to keep that as its suitably aged for the machine (1958), it's nice condition and did run fine.

 

[RogerS]

Sent you a PM. If you email me your photos I'll post them up here for you.

 

[guineafowl21]

Red, white and blue are the old phase colours 1, 2 and 3. They would connected to A, B and C respectively, and the green to earth.

I would give serious consideration to renewing the wiring - a satisfying job, and one that really needs doing as that old cable insulation can be so brittle. With a 40A breaker, that could result in some fireworks.

You should also install some beefy cable, say 6mm2 depending on type, between the plug and the switch. It needs to cope with overloads up to 40A as dictated by the breaker you have.

 

[1NRO]

Thanks fella's, the help is much appreciated. The solid advice hasn't fallen on deaf ears, as and when I take the machine to the 3 phase equipped workshop I'll have a sparky check all is well before startup. I'll change the wires as advised.

There's a part of me that resists paying for something I can do myself, I don't want that to rub folks the wrong way but it's important to me. It's how I learn. I can recognise when I need help and am grateful for all assistance.

 

[guineafowl21]

Yes, I’m the same. I bought a Megger BM10 for peanuts several years ago and have found it very useful for testing appliances and cars for insulation faults. Helped out a number of friends, too - ‘you couldn’t bring your machine over, could you?...’