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what are we actually reducing and increasing on changing the regulator value? Current,voltage.? Is it based on resistance or capacitance? Power losses? Can a regulator can be used for current controlling or voltage controlling?

akhil
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  • What sort of regulator is this? – pjc50 Jan 10 '13 at 09:47
  • its a simple ac 240V regulator. – akhil Jan 10 '13 at 09:54
  • [This answer](http://electronics.stackexchange.com/a/48404/14004) should provide some insight on how the typical fan regulators (dimmers) sold in India (Anchor etc) work. Basically, a triac controls the active part of the voltage cycle. – Anindo Ghosh Jan 10 '13 at 09:56

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I don't know your particular case because you provided too little information, but just as an example: The simplest regulators are based on potentiometers. It's very simple - potentiometer acts as a resistor in series with load, so it reduces both voltage and current in the actual load. These simple fan regulators can be found in cheap computer accessories. Their problem is low efficiency, because the energy is lost in the resistor as a heat.

Update: As I received minus votes for this answer, I must provide more information. In real world, especially in your 240 VAC case, regulators are usually based on triacs. It was discussed before here. If you look at the provided video, you can clearly see that the triac actually doesn't regulate the peak voltage, it regualtes RMS voltage. The load/device then "feels" or "thinks" that is being run on a lower voltage. Some devices don't like this, but many others work.

Another question was if current is regulated. The current is based on volt-ampere characteristics of the load. If the regulation will work and you will see changes like slower rotating fan or less bright bulb, then the current is lowered with voltage. U = I.R or U = I.Z, so loads with a constant resistance/impedance will have their voltage and current lowered together.

Note that triac based dimmers work with alternating current only.

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Al Kepp
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  • A fan regulator running on 240 Volt AC mains, as has been specified by OP in comments, is not going to be a potentiometer. – Anindo Ghosh Jan 10 '13 at 10:40
  • Yes, a PWM regulator is much more probable. – Al Kepp Jan 10 '13 at 11:07
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    For regulation of a mains-powered fan? A visit to an electrical supplies store will indicate that triac based regulators are pretty much the only ones sold. Old, stable technology, and very cheap to make. – Anindo Ghosh Jan 10 '13 at 11:10
  • No don't do AC motor regulation at 240V with a potentiometer. Apart from the fact that a potentiometer for this application must be huge, it is probably generating more heat that the fan can dispose of in the first place. – jippie Jan 10 '13 at 11:31
  • can i use it for Voltage Regulation – akhil Jan 10 '13 at 11:50
  • let me remind that,this regulator is having 20 years old technology. – akhil Jan 10 '13 at 11:53
  • Can you use it - it depends on the load. Look at the link provided by Anindo Ghosh. The triac based regulator, or dimmer, will not literally regulate the voltage, but the load may "feel" that it runs on a lower voltage. Because it "feels" them RMS voltage, not the peak voltage. Some loads don't like this kind of regulation, many other work. What you want to regulate? – Al Kepp Jan 10 '13 at 11:54