lowering voltage in extension lead - potential hazards?

[flameport]

The horrid description for that product and the maximum power rating of only 250W hints at what it really is:

The working principle of the single-phase AC motor governor is to connect the bidirectional thyristor in the motor control loop to control the conduction angle of the thyristor to control the terminal voltage of the motor.

It's a triac dimmer - the sort you can buy here: https://www.toolstation.com/axiom-push-dimmer-switch/p18884 or in any other similar outlet.
Will mostly work in a buzzing, overheating, burning up way with some types of motor, and not at all with others.

 

[JohnD]

What sort of 3 pin plug is that? -not come across that before

https://www.ebay.co.uk/i/1629358737...MIvLf47Ma_4wIViK3tCh1npQlQEAQYByABEgLfyfD_BwE

AUSTRALIAN PLUG RE WIREABLE 10AMP WHITE

£3.99
+ £3.29 postage

• Get it by Mon, 22 Jul - Tue, 23 Jul from Twyford, Berkshire

•  • New condition
•  • 30 day returns - Buyer pays return postage | Returns policy

RE -WIREABLE 10AMP RATED AUSTRALIAN PLUG WHITE. MOULDED CORDS & CABLES LTD. Also available in black. Item number: 162591160766. A GOOD QUALITY PRODUCT THAT IS EASY TO WIRE.
Read full description
See details and exclusions

see also

https://www.ebay.com.au/itm/Mains-P...-Australian-AU-3-Pin-Plug-White-/370870994311

 

[echoes]

Anyway, my concern is the lowered voltage in the extension lead. Would this not affect the RCBO operation in a fault condition? its a TT system.

The lowered voltage is not a concern, and the RCBO operation will not be affected by it.

Your main concern should be finding fans suitable for speed control, and a suitable controller.
As others have stated, induction motor + triac-based power controllers is asking for trouble.

 

[bernardgreen]

is this the thing? looks the job!

https://uk.banggood.com/AC-220V-Sin...Kds--wmqiQnX_kRoCAg0QAvD_BwE&cur_warehouse=CN

Another cheap and nasty item, it is not going to be well designed. It could fail by catching fire.

It is so badly described the description includes this strange feature Input speed: 1400 (rpm)

The input is mains electricity. not a rotating shaft.

If the manufacturer does not have the ability to describe it accurately then I would doubt he has the ability to design it.

As has been said. yopu cannot control the speed of your fans by reducing the voltage supplied to them.

 

[bernardgreen]

Actually a 60Hz device running on 50Hz will perform at approximately 20% less than the rated figure

The impedance of a winding designed for 60Hz operation will be lower at 50 Hz than it is at 60Hz. Hence the current will be higher. If the current carrying capacity of a 60Hz winding is marginal then at 50Hz the increase current could result in over heating and failure of the winding.

That sais many reputable manufacturers of 60Hz equipment will allow for the possible use ( mis-use ) on 50 Hz and use winding wire that canb safely carry the increased current.

 

[winston1]

https://www.ebay.co.uk/i/1629358737...MIvLf47Ma_4wIViK3tCh1npQlQEAQYByABEgLfyfD_BwE

AUSTRALIAN PLUG RE WIREABLE 10AMP WHITE

£3.99
+ £3.29 postage

• Get it by Mon, 22 Jul - Tue, 23 Jul from Twyford, Berkshire

•  • New condition
•  • 30 day returns - Buyer pays return postage | Returns policy

RE -WIREABLE 10AMP RATED AUSTRALIAN PLUG WHITE. MOULDED CORDS & CABLES LTD. Also available in black. Item number: 162591160766. A GOOD QUALITY PRODUCT THAT IS EASY TO WIRE.
Read full description
See details and exclusions

see also

https://www.ebay.com.au/itm/Mains-P...-Australian-AU-3-Pin-Plug-White-/370870994311

It was a Chinese plug not an Australian one. They may look similar and will (usually) fit each others sockets but Australian ones have sleeved pins and are fitted with the earth pin at the bottom. Chinese ones don't have sleeved pins and are fitted with the earth at the top. There is also a difference in the length of the pins.

 

[aptsys]

is this the thing? looks the job!

https://uk.banggood.com/AC-220V-Sin...Kds--wmqiQnX_kRoCAg0QAvD_BwE&cur_warehouse=CN

Probably need something more like this one: https://uk.banggood.com/custlink/DGG39Y0hVu

 

[Nozzle]

I particularly like the tag line for this Chinese export box shippin' firm: "Shopping with fun Best Bang For Your Buck".

Yes, best bang indeed. If you're going to have an electrical fire start in your house or workshop, may at least make sure it's an inexpensive one!

Nozzle