3500W 220V Power Supply???

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Granttruter

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I have a very simple circuit where I have a 14ohm load with a constant direct 220V supply and a current draw of 16A. The problem is that I have to limit my current draw to a max 3A at 220V. My first question is:

1. Is this possible?
2. If it is possible, how can it be done?
 
Apply ohms law, add a HUGE wattage resistor in series with the 14 ohm.

But what is the point?.
 
ya there is no way out rather than using a VERY HIGH wattage resistor!!!!!!
I would also like to know for what purpose are you going to use the circuit?
 
Need more info. Is the supply AC or DC. What kind of supply? What kind of Load? To what end?
 
Does the duty cycle have to be 100%? If not, a power transistor driven by a 555 timer could turn it on for 18.75% of the time would average 3A load on the mains but 16A to the load when it is powered. For instance, if the base frequency was 1 KHz, then if on for 187.5μs and off for 842.5μs should give you what you want.
 
Thanks to all for replies thus far.

The voltage is 220V AC, 50Hz and the load is a hot water element (14ohm). Can I limit the current draw to a maximum of about 3Amps?
 
How do I reduce the current draw from a hot water element?

How can I reduce the current draw from a hot water element to maximum of 3A from the main supply. The voltage is 220V AC, and the element resistance is 14Ω.
 
My hot water cylinder accounts for 80% of my electricity bill. By reducing the consumption of it to about 20% of the current consumption, will account for a drastic decrease in the electricity bill
 
Granttruter said:
My hot water cylinder accounts for 80% of my electricity bill. By reducing the consumption of it to about 20% of the current consumption, will account for a drastic decrease in the electricity bill
Click to expand...

It will also result in a drastic decrease in the amount of hot water you have - assuming it even gets hot anough to use?.

A well insulated hot water tank, with a correctly working thermostat, will heat the water to the required temperature, then switch off - the insulation keeps it warm for hours.

Your idea won't work - say it currently takes 1 hour to heat the water up, reducing the power to 20% will then take 5 hours to heat the water up - exactly the same cost, just five hours instead of one.
 
You could probably do it with a big triac. Do you want 3 amps all the time or just sometimes?
 
First, it is doubtful you will heat much water with P = IE = 3A*220V = 660W

P = E²/R, or E = √(P*R) =√(660*14)=96V

I would be looking for a 220V to 100v step-down transformer, rated at >700VA.

Some incandescent lighting solid-state dimmers are rated at 250V 700+W, and will work into a resistive heater.

And, don't double post on the same thread!
 
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Granttruter said:
My hot water cylinder accounts for 80% of my electricity bill. By reducing the consumption of it to about 20% of the current consumption, will account for a drastic decrease in the electricity bill
Click to expand...

Go read up on the Laws of Thermodynamics.

What you pay the electric utility for is Watt-hours Wh. At a lower power input, it will just take longer to heat the water; the Wh required will not change, neither will your bill.

To reduce Wh, you must:

1. reduce volume of water being heated.

2. reduce the temperature of the water above ambient temperature

3. Insulate the water heater tank and pipes to minimize the heat loss to ambient.
 
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Use a 750 Va 120/240:12/24 transformer set up to work as auto transformer to deliver 96 volts to the 3200 watt element. You will get roughly 20% of the normal power output then.

You use the 120:240 primary windings to split your mains voltage and then use the 12:24 secondary windings to buck that center tap voltage the rest of the way down to 96 volts. Its a simple and very efficient way to reduce your power consumption per hour.

But you will still find you use the same average power per month any way it will just take your water heater 5 times longer on every cycle to catch up.
 
You would be better off turning down the temp and insulating the tank and pipes. I just remembered a trick I learned in school. If you rectify the supply and use half wave pulsing DC your power will drop to 1/4 of the origanal. It would have to be a realy big rectifier! Andy
 
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