Looking for 4-way 250v rotary switch

[JohnW2]

Are the different windings all completely separate, or are they commoned at one end?

FWIW, the last one of those I dissected appeared to have taps on a single winding - hence one common 'end'.

Kind Regards, John

 

[oldcelt]

Are the different windings all completely separate, or are they commoned at one end?

Sorry, I don't know. I'd have take it all apart again to try to identify what the connection layout is. I haven't been able to find a wiring diagram anywhere.

I simply don't have time to take it to pieces again just at the moment.

 

[ban-all-sheds]

Also, decide if you do actually need all 3 speeds, or only 2, and if you do need all 3 if there's one which you use most often, i.e. the one you mostly use when turning the fan on.

 

[oldcelt]

Also, decide if you do actually need all 3 speeds, or only 2, and if you do need all 3 if there's one which you use most often, i.e. the one you mostly use when turning the fan on.

For the moment I've left the switch on medium setting and we control on/off by switching the connector box (where flex meets up with cabling).

 

[stillp]

It might be possible to create a new mechanism using a casting resin. Using the bits of the broken one to make a mould. A lot of work but can be worthwhile.

Th company I used about 20 years ago no longer trades but this

http://www.ecfibreglasssupplies.co.uk/c-116-polyester-casting-resins.aspx

company appears to supply the resin and the moulding materials.

I've made a new part for a switch (for a compressor) using some 2-part epoxy repair putty. Can be moulded like Plasticine, sets in about an hour.

 

[ban-all-sheds]

It's almost certainly just a simple 4-position switch for a tapped winding on a simple motor.

It almost certainly does not need to be DP. It almost certainly doesn't matter if it's BBM or MBM.

It almost certainly could be replaced with any rotary switch with the right electrical rating, either in the hood or in an enclosure nearby.

Or if 2 out of the 3 speeds will suffice it could be replaced by a 2-way centre-off rocker switch.

If all 3 speeds are needed it could be replaced with two 2-way centre-off rocker switches, albeit at the expense of a little bit of strange operation which would soon become second nature.

There are many options to explore before trying to rebuild the old switch using epoxy putty.

 

[bernardgreen]

It's almost certainly just a simple 4-position switch for a tapped winding on a simple motor.

It almost certainly does not need to be DP. It almost certainly doesn't matter if it's BBM or MBM.

If a Make Before Break ( MBB ) is used then as it moves from one position to the next it will put a short across part of the motor coil. If the motor is running this short will be high current, enough to damage switch contacts and possibly damage the windings.

Some switches used for tap changing on motors even though they are Break Before Make ( BBM ) are designed to have increased separation between the fixed contacts to ensure contacts are not damaged by maintained arcing when tap changing happens.

It almost certainly could be replaced with any rotary switch with the right electrical rating, either in the hood or in an enclosure nearby.

"" the right electrical rating "" of course, just decide exactly what is the right electrical rating.

And if I read correctly the switch also controls the lamp so a second pole is needed.

 

[oldcelt]

And if I read correctly the switch also controls the lamp so a second pole is needed.

The lamp is controlled by a separate on/off switch.

The entire hood is protected with a 5A fuse in the connection unit so current is not going to exceed that. Voltage is normal household 220AC. The switch I've been considering is specified as:-
AC440V 10A 4 Position 2Pole Universal Rotary Cam Changeover Switch.

The only information not included in the spec is whether it's MBB or BBM. I'm waiting for an answer from the supplier to my question.

If BBM then would you think it's a suitable switch?

 

[ban-all-sheds]

If a Make Before Break ( MBB ) is used then as it moves from one position to the next it will put a short across part of the motor coil.

No it won't.

If the motor is running this short will be high current, enough to damage switch contacts and possibly damage the windings.

L connected to two taps - what current will flow where?

Some switches used for tap changing on motors even though they are Break Before Make ( BBM ) are designed to have increased separation between the fixed contacts to ensure contacts are not damaged by maintained arcing when tap changing happens.

What sort of size are these motors, and what currents and voltages are involved?

"" the right electrical rating "" of course, just decide exactly what is the right electrical rating.

Yes - the OP will need to know what load the motor is to be able to select an appropriate switch, e.g. at least 230V, at least 1A inductive. Or whatever.

And if I read correctly the switch also controls the lamp so a second pole is needed.

I didn't read that.

 

[JohnW2]

If a Make Before Break ( MBB ) is used then as it moves from one position to the next it will put a short across part of the motor coil.

No it won't.

?? What is your understanding of the functionality of a MBB switch?

If the motor is running this short will be high current, enough to damage switch contacts and possibly damage the windings.

L connected to two taps - what current will flow where?

What about the voltage/current induced into the 'shorted' part of the coil? AFAICS, the connection to L (or anything else) is not relevant.

Kind Regards, John

 

[ban-all-sheds]

 

[oldcelt]

All fascinating stuff I'm sure but to get back to the subject if I may, would the switch I mentioned be suitable in the opinion of you experts?

 

[bernardgreen]

Looks like an auto transformer with a shorted winding.