Can someone please explain this

[rantoftheday]

Can someone please explain clearly, concisely and briefly what power factor is

I've tried looking at various sites and they go way too far in depth and I get lost.

I just want to know in Laymans terms what it is

And I would also like to know the difference between VA and Watts, again clearly and briefly, explained like i'm an idiot, which some may argue that I am!

The guys in work don't really know how to explain well either

 

[Deleted member 9648]

On AC systems with inductive loads if you put an ammeter on the system the total current would consist of two components..one is the current producing a useful effect,ie; converted into useful energy....the second is a magnetising current,this is an inevitable result of inductive loads but does no useful work.Never the less it is being drawn from the mains and hence being paid for. Power factor is in effect a percentage the useful current is of the total current drawn.
ie;...a power factor of 80% or 0.8 would mean 20% of the total energy being drawn is wasted.
Power factor correction simply involves reducing the useless magnetising currents to a minimum.
VA is the power taking into account power factor...watts does not take into account power factor and hence really only applies to resistive loads.

 

[Knobhead]

Have a look at http://en.wikipedia.org/wiki/Power_factor It’s the best I can find to explain a very complicated subject.

I’ll try to sort something out for you. (I started to write out a description and confused myself)! It’s going to take me a while to do a drawing of it but it’s the easiest way around it.

 

[GLENNSPARK]

On AC systems with inductive loads if you put an ammeter on the system the total current would consist of two components..one is the current producing a useful effect,ie; converted into useful energy....the second is a magnetising current,this is an inevitable result of inductive loads but does no useful work.Never the less it is being drawn from the mains and hence being paid for. Power factor is in effect a percentage the useful current is of the total current drawn.
ie;...a power factor of 80% or 0.8 would mean 20% of the total energy being drawn is wasted.
Power factor correction simply involves reducing the useless magnetising currents to a minimum.
VA is the power taking into account power factor...watts does not take into account power factor and hence really only applies to resistive loads.

Yes excelent mate. ...With a resistive load both current and voltage can be said to be "in phase" with each other....an inductive load such as moters etc will cause a current lag which is an inefficient use of energy and will also instigate "inert currents" which have a serious effect on the current carrying capabilities of cables.....this of course doesn`t just stop at the origin of supply as we know it (cutout/s) but will of course affect the DNOs supply cables n all together with the DNO saying "your nicking ALL the available energy were trying to provide for yourself and others.............

 

[GLENNSPARK]

I might also like to add .....that a DNO can (and probably will) fine you for introducing a "dirty"...or high inductive load (below 0.8) onto their network.............

 

[i=p/u]

well heard of that glenspark you can get fined.... so if that circuit was on rcd , would it trip cause it lags, or wasted or am i talking poo

 

[GLENNSPARK]

well heard of that glenspark you can get fined.... so if that circuit was on rcd , would it trip cause it lags, or wasted or am i talking poo

Smell it from here mate!.....Think about it ipu
Current FLOWS AND RETURNS yes..?....so how the hell is an RCD going to detect that?....

 

[i=p/u]

im not happy paying for it and they taking it back,

 

[GLENNSPARK]

im not happy paying for it and they taking it back,

listen here you yue cheeky liitle get!...Im off to work now and i will not be back till late! so you got it all to yourself now ant yere!....pm you later ok ipu......gobby .........

 

[Knobhead]

Will you two please play nicely otherwise I can see you both being on the naughty step.

 

[Guest123]

It is difficult to explain to a layman but I too will have a stab at simplifying.

To understand power factor (PF) you first need to understand how different items of current using equipment use the electricity supplied to them.

Electricity supplied to any item of current using equipment is supplied in volt-amps (VA), which is simply a product voltage x amps and is called Apparent Power. The amount of electricity the item of current using equipment actually uses i.e the work done by it, is measured in Watts (W) or Kilo-Watts (KW) and this is called the True Power.


Now, power factor by definition is the ratio of True Power to Apparent Power so using a simple example, if we supplied an item of equipment with 1000 VA of Apparent Power but the item only used 800 W of this Apparent Power which would be the True Power The power factor would be 800W / 1000 VA = 0.8.

Put simply power factor (PF) = True Power / Apparent Power.


Now as I've said this is a very very basic description of what power factor is and I've left a lot out to try and make it easier for you to understand.

Hope this helps.

 

[Engineer54]

The difference between Apparent Power and True Power often being called ''Watt-less Current''

 

[fazhols]

Hi guys. Let me try.

From basic physics watts is a measurement of energy. For electrics the formula is watts = volts x amps. Or w= va. So, watts and va are the same thing.

Now some things are not efficient so although a circuit and current have the ability to deliver power (watts) of volt x amps the device such as a motor may not be able to translate 100% of the potential to actual power.

As an example, a 250v x 4 amp circuit can at 100% efficiency can deliver 250 x 4 = 1000 watts. But a 1000 watt appliance may not be efficient so in reality may need 250v x 5 amps = 1250 watts to push out 1000 watts of power.

This difference is The power factor. Power factor of 1 means 100% efficiency while factor of 0 means 0 efficiency.

So. Va= watts = power. How powerful is your drill? 1000 watts or 1000 va.

Power factor is how efficient the drill is at converting supplied power into actual power.

 

[Nolnoc]

I love this forum for the above answers. Everyone sharing there expertise and experience.
My question is can wattless energy be harvested. I was doing a job in a factory recently and the electrical engineer said he was going to use the wattless energy to heat water in the factory. Didn't think it would be possible but was not in a position to disagree. Haven't being back since so don't know outcome.

 

[fazhols]

Just wanted to add. If the drill can deliver 1000 watts of power but needs 1200 watts ( or va)
of electricity to do so Then it's power rating is 1000 divided by 1200 = Power rating of 0.83

Hi guys. Let me try.

From basic physics watts is a measurement of energy. For electrics the formula is watts = volts x amps. Or w= va. So, watts and va are the same thing.

Now some things are not efficient so although a circuit and current have the ability to deliver power (watts) of volt x amps the device such as a motor may not be able to translate 100% of the potential to actual power.

As an example, a 250v x 4 amp circuit can at 100% efficiency can deliver 250 x 4 = 1000 watts. But a 1000 watt appliance may not be efficient so in reality may need 250v x 5 amps = 1250 watts to push out 1000 watts of power.

This difference is The power factor. Power factor of 1 means 100% efficiency while factor of 0 means 0 efficiency.

So. Va= watts = power. How powerful is your drill? 1000 watts or 1000 va.

Power factor is how efficient the drill is at converting supplied power into actual power.

 

[telectrix]

and for the benefit of any female sparks reading this thread, power factor has absolutely no connections with max factor. (runs to find tin hat)

 

[i=p/u]

and you dont wire it up i=p/u

 

[Cyberprog]

I love this forum for the above answers. Everyone sharing there expertise and experience.
My question is can wattless energy be harvested. I was doing a job in a factory recently and the electrical engineer said he was going to use the wattless energy to heat water in the factory. Didn't think it would be possible but was not in a position to disagree. Haven't being back since so don't know outcome.

Remember that in a lot of cases the energy in question is converted into heat and movement, so if he's running some large machines which generate a lot of heat as part of the process, he may be able to capture that heat (energy) using a heat exchanger.
Whether this would be a net gain however depends how much energy has to be inserted to capture the energy in terms of, for example, pumping water through the heat exchanger, and indeed in the initial outlay of piping it all up.

 

[Engineer54]

I love this forum for the above answers. Everyone sharing there expertise and experience.
My question is can wattless energy be harvested. I was doing a job in a factory recently and the electrical engineer said he was going to use the wattless energy to heat water in the factory. Didn't think it would be possible but was not in a position to disagree. Haven't being back since so don't know outcome.

Not in the sense you have taken it!! The only way this Engineer can harvest this wattless current, is by correcting the PF with capacitors at the main switchboard. Which is generally the normal method of not having to pay the leccy companies for all this wattless current, that bigger industrial/commercial installations will suffer from.

Having corrected, then he can provide water heating, (pure resistive load) by using the money saved, to pay for the running costs of the water heater(s)

Now the PF correction by capacitor banks etc ,at the main switchboard will only correct upto the point of capacitor bank connection, everything after the connection point will be still affected by the Original high PF. Companies are not usually too conserned about this, unless they need to free up capacity on sub-main cables. If that's the case, additional capacitor correction will be required at the source, ...ie at large motor terminals, or other large inductive load source's.

 

[Engineer54]

Remember that in a lot of cases the energy in question is converted into heat and movement, so if he's running some large machines which generate a lot of heat as part of the process, he may be able to capture that heat (energy) using a heat exchanger.
Whether this would be a net gain however depends how much energy has to be inserted to capture the energy in terms of, for example, pumping water through the heat exchanger, and indeed in the initial outlay of piping it all up.

You'll still need motors to pump the water thru a heat exchanger. Not very cost effective at all. Unless the whole plant has been set-up for such a system, which would i believe, be an extremely rare occurance in the UK!!