Help wiring an electric motor

[threedee]

Any cheap options of this ? All i find is way more expensive than the motor itself...

 

[Aragorn84]

Might find a used one on ebay?

Theres also a chinese no-brand VFD on there for £50 that claims upto 3kw that might do the job if it didnt implode and actually does what the specs claim...

 

[matt1e]

I think the lights go dim because its meant to be a 3 phase motor, converted to run on single phase with a capacitor to provide the 3rd phase. Someone may correct me though, I'm no expert.

Ok I will steve, it's single phase only mate

The dimming of the lights is due to inrush as RF has described
Direction control is how RF describes
speed control is also how RF describes
The 'clack' is the sound of the internal spring loaded centrifugal switch closing as the motor spins down

Matt

 

[SimonH2]

You need to change the position of two links between four terminals.

Actually, it is quite easy to do with a switch - and you call yourself a sparky ?
2P C/O with centre off would do it, though really it wants to be 3P so the live can be disconnected as well rather than just switching the neutral (or swap L & N so the 2P switch is in the live). Ideally the 3rd pole would me make last/break first so the power goes off before the windings are switched round.

The lights dim as this is an inductive load, and when you first power it up, it is effectively a short circuit until the magnectic field gets established.

It's not so much the magnetic field as that'll be established within one mains cycle. It's the high current taken by a motor until it's up to speed and the back-EMF acts to counteract it (simplifying things a bit).
EDIT: The initial inrush (sub mains cycle) may (depends on when the switch is closed) indeed cause a massive volt drop - but typically not for long enough to be really noticeable. It's the longer (could be a second or few) time taken for the motor and load to run up that people tend to notice.

This is known as inrush current, and is normal.

Agreed.

The only way to speed control it would be to use an invertor. This gives you infinately variable speed, soft start, so no more dimming of your lights, and forward and reverse control too.

This motor isn't really suitable - unless it run above a certain speed then the start winding will be in circuit and it'll take an excessive current and probably burn out (or blow the CFD, or blow a fuse). If speed control is wanted, then it's best to get a 240V 3P motor and one of the small (sub £100) inverters which are normally designed to drive 3P motors. A capacitor run (not start cap & switch) would work, but last time I looked, there weren't that many CFDs designed for single phase motors - I recall looking for some a while ago to run (with remote/computer control) some 1P fans at work.

Sorry, not meaning to pick on you RF, though it does look a bit that way

 

[threedee]

Note: Kettle, 3.5kW, does NOT dim the lights.

 

[bernardgreen]

Note: Kettle, 3.5kW, does NOT dim the lights.

The motor will be taking a lot more than its rated power until it is running at full speed. Depending on type of motor the power taken at standstill can be more than ten times the rated power.

 

[SimonH2]

2P C/O with centre off would do it, though really it wants to be 3P so the live can be disconnected as well rather than just switching the neutral (or swap L & N so the 2P switch is in the live). Ideally the 3rd pole would be make last/break first so the power goes off before the windings are switched round.

Correcting myself now I'm awake
Yes it needs to be a 3P switch, a 2 pole switch would switch off the start winding but leave the main winding connected.

For example, this one from RS - you'll need additional items such as mounting plate, handle, etc. More details in PDF. However, check the AC11 rating (6A for this switch) against the rating of the motor and choose a higher rated switch if necessary.

Wire supply live to 2 & 6, supply neutral to 10 and N (U2) connection on motor. Wire 1 & 3 to L (V2) on motor, 7 & 9 to V1 on motor, 5 & 11 to Z2 on motor. Leaving off both links - store them safely (fastened securely inside the terminal box) in case they are needed again in future - there's nothing worse than finding some **** has lost the links or removed the wiring diagram when trying to reuse an old motor.
If the motor rotation is "wrong way round" relative to switch position, then swap the connections from the swith to V1 and Z2 - ie 7 & 9 to Z2, 5 & 11 to V1.

 

[SimonH2]

Oops, I wasn't as awake as I thought, so correcting myself again

Terminal 6 on the switch should connect to U1 in the motor, not supply live. That way, it picks up the supply after the overload cutout K. As it was, the overload would interrupt the power to the main winding, but still leave the start/run winding powered.

I should really draw these things out first

 

[Mindaugas]

Hello,
I also have the same motor and I have a question about wiring pinout. There are 8 wires: U1 V1 Z1 U2 V2 Z2 and two white wires. What are these white wires and what they do? It is used as a contact between V1 and V2, when running CW?

 

[SimonH2]

Are the white wires labelled S1 and S2 ?
According to the diagram given by the OP, they are connected to a centrifugal switch for starting.

When the motor is not running, the switch labelled K on the left of the diagram is closed. When power is applied, additional power is applied via the starting capacitor (Cst) to give better starting torque. As the motor runs up, the switch opens and only the running capacitor (Cr) is used to help provide a "third phase".

I need to take a better look at the diagrams when I'm actually awake - they don't quite make sense as the difference between CW and CCW wiring isn't just reversal of a winding.

 

[Mindaugas]

Are the white wires labelled S1 and S2 ?
According to the diagram given by the OP, they are connected to a centrifugal switch for starting.

When the motor is not running, the switch labelled K on the left of the diagram is closed. When power is applied, additional power is applied via the starting capacitor (Cst) to give better starting torque. As the motor runs up, the switch opens and only the running capacitor (Cr) is used to help provide a "third phase".

I need to take a better look at the diagrams when I'm actually awake - they don't quite make sense as the difference between CW and CCW wiring isn't just reversal of a winding.

Thank you for your reply. The white wires are without labels. I have tested these wires and they are short circuited. It is possible that they are centrifugal switch as marked K in schematic?

 

[SimonH2]

Most likely. If you can spin the motor up, eg with a piece of dowel in a drill applied to the end of the shaft, then you'll probably find that the short circuit opens.

 

[securespark]

Am I reading the diagram wrong?

As I see it, you are not changing the positions of the links, merely removing them for a change of direction.

In theory (not that this would be acceptable in practice), you could wire a DP switch to changeover, but you would have to switch off first.

 

[ban-all-sheds]

Am I reading the diagram wrong?

Yes.

As I see it, you are not changing the positions of the links, merely removing them for a change of direction.

No.

 

[securespark]

My bad eyesight strikes again...