# Electronic Circuits and Projects Forum

1. ## power saver circuit

Could anyone tell me what sort of circuit is used in power savers commonly available on the net by mail order. these can be plugged into home sockets so that you have less usage of electricity especially when you use a/c in summer or fridge and deep freezer. one method i saw on net was to fit a mains capacitor to correct power factor across the motor terminals. Are there any other electronic circuits for reducing voltage to reduce electricity consumption of a/c motors?

2. There is a reason why they take the amount of power they do; SO THEY WORK PROPERLY! If you try to do something to use less power to them, then you will make them less efficient at the job they should be doing. If you want to cut on A/C costs, get a few fans. They are about \$20, and they work awesome.

3. That's right they are mearly power factor correction devices. Motors and other inductive loads draw a lagging current, all these units do is introduce some capacitance to ballance it an lower the current consumption. They do not actually lower the power consumption of the device itself, they just reduce the current consumption. Power is saved but only because the current is lower hance the R squared I losses are lower.

These units won't reduce your bill by much as you're most likely billed by the power you use rather than VA. However these power savers are still a good idea since the save losses in the cables and therefore they're good for the enviroment.

4. I need a power saver circuit diagram with specification.

5. There is actualy a energy saving device called a Watt Wizard or a Green Plug. It slightly varies the voltage going into a inductive load type devices like air condioiners, refrigerators and freezers. It varries the voltage proportinaly to the to the load to keep the internal inductance losses down.
In some devices the induction motor is running a very light load at times. If the incoming line voltage is dropped to a lower level the total energy loss in the motor goes down. Being able to reduce the line voltage when the load is light will save energy.

It does actualy reduce the total wattage a device uses but not much. I have had one for about 15 years. I have in fact ran it through an actual spinner type watt meter and found that it does in fact Work! BUT the actual savings is small.
Its the only energy saving device on the market that I have found that actualy does some small but measurable good!

For what one costs it would still take years to pay for itself by avoided cost comparison.

6. Industry is billed extra if their power factor is poor. A home is not because a home's meter ignores a poor power factor.

The "energy saving" device is just an over-priced capacitor. Its value might be too high or be too low. It saves money for the electrical utility if its value is correct for your inductive appliances but since the appliances turn off and on then the capacitance is frequently too high so it costs the electrical utility more, not less.

7. I would hope that it's an array of capacitors which are connected or disconnected according to the power factor.

8. I just installed one in my water pump last week, got the power saver from china with brand name 'Power Star'. Upon checking, using a clamp meter, i got 0.4amps reduction which if i multiply with line voltage of 230VAC, i can reduce around 90watts. I hope this can give some savings on the actual bill as well..

9. And how are you measuring the efficiency of the pump? Reducing current isn't going to increase efficiency if the pump just has to run longer. You can't get something for nothing.

10. I suspect its similar in operation to the watt wizard I have. It will save but the realistic savings will not likely ever off set the purchase cost!
I still watch auctions and garage sales for them though. If you pay under \$3 they are cost effective!
For refrigerators, freezers, water pumps, heat pumps, and air conditioners they do work but not as great as they advertise!

If you get the chance to buy one used for cheap get it! You can spend more money on worse stuff!

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Electronic Circuits  |  Learning Electronics

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