220V 4000W Variable Voltage Regulator Speed Motor Fan Control Controller

[blackrose]

Does anyone know if these things are available from a more reputable manufacturer or supplier?

 

https://www.ebay.co.uk/itm/125907936986?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=lszatw8hs2k&sssrc=4429486&ssuid=SV_sF0T7SiS&var=&widget_ver=artemis&media=COPY

 

There are lots on Amazon with variable reviews, some pointing to bare wires near metal casing or non standard unfused plugs. They all seem to come from China which is fine as long as they're safe and don't burn the boat down. 

 

Also is this the sort of thing that might damage an inverter?

 

 

Edited June 23, 2023 by blackrose

[BEngo]

Lots of variable frequency (aka inverter)  drives (VFD)  about. What do you want to vary the speed of?

 

Newton Tesla are one reputable VFD  supplier who will by many accounts sort out a one-off.  A look in Model Engineer,  Engineering in Miniature and Model Engineers Workshop at  WH Smiff should find you a few more.

 

The item linked has a number of engineering inconsistencies:

 

4000W is overloading a 13 A plug top.  Overheating is very likely.

 

9A is nothing like 4000W, more like 2250W if the local grid has a tailwind.

 

18A at max power is overloading a 13A socket. Dependent on type  the socket will not like this.  The plug won't  

 

I would not recommend this.

 

N

[blackrose]

42 minutes ago, BEngo said:

Lots of variable frequency (aka inverter)  drives (VFD)  about. What do you want to vary the speed of?

 

 

I want to reduce the power draw of my 1kW immersion heater so it works better with solar.

 

Doing that in conjunction with an immersion timer is a cheaper option than a proper 12v dump load and saves changing the immersion.

Edited June 23, 2023 by blackrose

[Jen-in-Wellies]

46 minutes ago, blackrose said:

 

I want to reduce the power draw of my 1kW immersion heater so it works better with solar.

 

Doing that in conjunction with an immersion timer is a cheaper option than a proper 12v dump load and saves changing the immersion.

A resistive load at 5A maximum then.

[MtB]

I'd have thought "reducing the power draw" of an immersion heater would make it 'work worse'. 

 

 

 

 

[blackrose]

5 minutes ago, MtB said:

I'd have thought "reducing the power draw" of an immersion heater would make it 'work worse'. 

 

 

Yes that's the idea. Instead of the full 1kW being drawn, say half of which comes from the batteries, if you draw only 0.4kW that will come from the solar controller - assuming the sun is out. If not then at least you're not drawing the full 1kW from the batteries. It's just an alternative to the 300w 12v dump load immersion.

 

So does anyone know of a decent unit?

Edited June 23, 2023 by blackrose

[BEngo]

I am not sure even a decent unit will do what you want with an immersion. It is meant for fan motors. It depends how it works.

 

If it varies the output voltage, it will work after a fashion.

If it varies the output frequency it won't.

If it works like a cheap solar controller by varying the mark:space  ratio  then it should be OK but will struggle to get below half power I think.

 

What the immersion will make of it I dunno.

 

N

[rusty69]

3 minutes ago, BEngo said:

I am not sure even a decent unit will do what you want with an immersion. It is meant for fan motors. It depends how it works.

 

If it varies the output voltage, it will work after a fashion.

If it varies the output frequency it won't.

If it works like a cheap solar controller by varying the mark:space  ratio  then it should be OK but will struggle to get below half power I think.

 

What the immersion will make of it I dunno.

 

N

 

The method certainly works using a variac, as I have tried it, albeit as a trial only.

 

I believe @TheBiscuits may have also used something similar to the link in the first post to connect to a 1KW immersion. 

[nicknorman]

43 minutes ago, BEngo said:

I am not sure even a decent unit will do what you want with an immersion. It is meant for fan motors. It depends how it works.

 

If it varies the output voltage, it will work after a fashion.

If it varies the output frequency it won't.

If it works like a cheap solar controller by varying the mark:space  ratio  then it should be OK but will struggle to get below half power I think.

 

What the immersion will make of it I dunno.

 

N

The device in question says it uses thyristors (or more likely a triac). It is basically just a jumped up incandescent light dimmer. So it will vary the input power to the immersion heater satisfactorily. The only question is, how does an inverter feel about the power being chopped every 1/2 cycle. It will probably be OK but personally I would be a bit uncomfortable about it, unless I had a cheap inverter.

[GUMPY]

Silly idea of the week!

Get a 120volt inverter and use it to feed the immersion🤔

[MtB]

20 minutes ago, GUMPY said:

Silly idea of the week!

Get a 120volt inverter and use it to feed the immersion🤔

 

Great idea!

 

It will cut the immersion power from 1kW to 250W.

 

Cue a string of posts arguing about why...

 

 

 

 

[nicknorman]

1 hour ago, GUMPY said:

Silly idea of the week!

Get a 120volt inverter and use it to feed the immersion🤔

I think that’s a good idea!

[Jen-in-Wellies]

54 minutes ago, MtB said:

 

Great idea!

 

It will cut the immersion power from 1kW to 250W.

 

Cue a string of posts arguing about why...

 

 

 

 

 

Power = V²/R in a resistive load. Half the voltage, quarter of the power.

[MtB]

1 minute ago, Jen-in-Wellies said:

 

Power = V²/R in a resistive load. Half the voltage, quarter of the power.

 

I think of it as Power = IV

 

Halve the voltage and the current will halve too.

 

So instead of IV you now get I/2 x V/2 = IV/4

[smiler]

500w immersion element?

[Tractor]

These are ‘triac’, Voltage control devices, switching the single-phase supply in order to regulate the Voltage, an action which will generate some disturbance seen by the inverter. If the aim is to use spare capacity form the solar installation and ‘dump’ this into the water tank, then the idea is good. Some control will be required to ensure the energy is surplus for use and will not removing energy from the batteries.

As there are many of these circuits on the market, you are right to be wary as the switching may not be tolerated by the inverter, and other devices operating on this supply. Testing in situ is the only way to be sure.

 

[blackrose]

14 hours ago, BEngo said:

I am not sure even a decent unit will do what you want with an immersion. It is meant for fan motors. It depends how it works.

 

If it varies the output voltage, it will work after a fashion.

If it varies the output frequency it won't.

If it works like a cheap solar controller by varying the mark:space  ratio  then it should be OK but will struggle to get below half power I think.

 

What the immersion will make of it I dunno.

 

N

 

Ok, they say they work for heaters so I assumed immersion heaters would not be that different.

8 hours ago, smiler said:

500w immersion element?

 

That means changing the immersion and if I'm going to all the trouble of doing that I'll do it properly and get a 12v dump load immersion kit.

8 hours ago, Tractor said:

These are ‘triac’, Voltage control devices, switching the single-phase supply in order to regulate the Voltage, an action which will generate some disturbance seen by the inverter. If the aim is to use spare capacity form the solar installation and ‘dump’ this into the water tank, then the idea is good. Some control will be required to ensure the energy is surplus for use and will not removing energy from the batteries.

As there are many of these circuits on the market, you are right to be wary as the switching may not be tolerated by the inverter, and other devices operating on this supply. Testing in situ is the only way to be sure.

 

 

Ok thanks for the advice