Power factor correction circuits

** Are they now ? Really ?

Fridges, electric ovens, microwave ovens, electric water heaters, air conditioners and even room fans all draw sine wave current with low to zero power factors.

All the other common domestic loads are either very small or used so infrequently that do not matter at all.

Domestic PFC is a massive red herring.

.... Phil

** More precisely, they all have unity to near unity power factors.

Just needed to get in first ...

... Phil

The IEC 61000-3-2 Harmonic Line Spec, the last time I checked, did not have limits for equipment running on 120vac. (only limits for 220vac) That means 120vac equipment is exempt. It's odd the 'clause' is hidden in the Scope section.

Cheers

There's no point in talking back to this guy -- he puts mediocre, misleading stuff on his site, then puffs it off here, but he never looks at the threads he starts.

--
www.wescottdesign.com

OK I know it most likely won't do any good, but I just went here,

and asked him to stop spamming us.

George H.

Never heard of killfiles?

I missed the start of this thread because I've had the OP auto-plonked for some time... as well as Phyllis >:-}

So, if Tim and you hadn't fed the troll, I wouldn't have been annoyed at all.

However, PFC is NOT a red herring... it's significant enough that my HK clients are fretting over dimming LED lighting systems while maintaining a good power factor.

PFC regulations were instituted at the behest of the power companies. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

** But domestic PFC clearly is.

Context shifting is the same as lying.

it's significant enough that my

** Commercial electronic lighting needs PFC and effective soft start circuits.

Without PFC, current consumption would far exceed the ( magnetic ballast) fluorescent lighting it's intended to replace - meaning that it could not in fact replace it.

** But not because of domestic loads.

... Phil

Only fully loaded transformers and motors have near unity PF, partially loaded have quite significant reactive currents, thus a lower factor will exists. Microwave ovens have rectifiers, so a PFC is needed.

Why is the reason for such a distinction ?

Is it because 220/280 V systems are usually three phase (with 120 degree phase shift between phases), in which the third harmonic currents for all three phases are summed into the neutral conductor, which is causing a lot of problems ?

The 120/240 V distribution is mainly 180 degree antiphase, so much of the harmonic currents are canceled and only a small amount of harmonic current flows into the neutral conductor ?

North America does have three phase.

piglet

I respond to Phil when he's being a worthwhile human being. When he falls off the wagon (whatever wagon it is that he falls off of), then I try to ignore him, or make snarky comments.

Yup. You pay for your watts, but to a large extent the power company pays to generate and distribute amps -- so they care about power factor.

--
www.wescottdesign.com

Yep. The power companies play the public like there's something in it for them, but the reality is that good PFC lets the power companies sell more power with the same infrastructure (and cost). ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Which is cheaper, pfc in appliances or paying for the added costs of more VA instead.

NT

Not residential and not 120/240V.

Really.

Oh really?

Jamie

Jr.:

h of

I would guess it is 120/208 not 120/240 ;)

-Lasse

You must live in the woods then, I have two different circuits of 3 phase in front of my house and can get transformers installed any time I would like.

Jamie

I suppose your residence would be in front of your house. Most of us live *in* the house.

No.. I have 2 major 3 phase feeds in front of my house.. I can get transformers installed to get 3 phase of 480 or 220.. etc.

You must be thinking of power they use at complexes off of a delta type transformer, where 120 is power and 208 is used as lighting. I don't have that her nor is not what I was referring to. This would be a separate service and meter, I would still have the 120/240 split phase from the pole pig.

Jamie