Power factor and domestic electricity billing in the UK?

[Uncle Peter]

I could have a three phase generator with the neutral grounded, and only supply one phase to a load. It would be bad for the generator bearings though I would think.

[harryagain]

All our three phase transformers in the UK reducing from medium/high to low voltage are star delta configuration. The primary winding is delta (or mesh) and the secondary winding is star.

The only exceptions are for special purposes,

[Uncle Peter]

Like this?

How are the windings PHYSICALLY arranged?

[Andrew Gabriel]

Yes.

For single phase, you have just a third of it - a single transformer with primary between two HV phases, and secondary with the neutral side grounded. Again, the load on that single-phase secondary is spread between two of the HV phases.

Varies with size and manufacture. Search for pictures of power transformers.

[John Rumm]

Its not easy once the harmonic content has been created. The PFC built into modern SMPSUs will suppress the creation of it by spreading the duration of the current draw by the PSU - rather than just concentrating it at the peak of the voltage waveform.

[Uncle Peter]

These are modern SMPSUs, just very cheap ones (about half the price).

[John Rumm]

Anything over 75W is required to have PFC these days...

[Andrew Gabriel]

and for electronic ballasts for lighting, anything over 25W, including CFLs with integral ballasts.

[Uncle Peter]

They have passive PFC. But that's shit. It's still got a PF of 0.67 measured by a few meters. Verified by 2kW of it heats up the wires as much as 3kW of heater.

[Uncle Peter]

Required isn't the same as has.

[Andrew Gabriel]

I only have one CFL over 25W (a 30W one from Homebase many years ago - they don't do them anymore), and it does have a PF of almost 1. This is probably also partly why most consumer CFL retrofit ranges stop below 25W.

As for separate electronic ballasts, they've all been PF > 0.9 for probably a decade or more. Once the design and initial roll-out is done, there is next to no additional cost anymore. These products are extremely high margin anyway - the component costs are tiny compared with the selling price.

[Uncle Peter]

Or most people don't have bulbs brighter than 100W equivalent. Mind you I've got 8 of those CFLs (under 25W) in my living room. So that's a lot more than 25W, and no PFC.

Presumably the same is not true for PC PSUs? Only the expensive ones have proper active PFC.

[The Natural Philosopher]

In fact you can do better than that as well by not smoothing the input (too much) so you are operating on very 'ripply' DC to generate the output.

[harryagain]

Normally they are on three parallel limbs. Physically parallel that is. A primary winding and a secondary winding on each limb. Pix here.

[John Rumm]

I just checked a few budget ones I have in the cupboard - all of them claim to have PFC

[John Rumm]

I would not trust the plug in meters when measuring harmonic PFs

How are you measuring the temperature and heat loss from the wires?

[Uncle Peter]

I also measured current with a few different meters, and the output current of the 12V DC supplies.

With my fingers. At 2kW, the wires are pretty warm. Adding another kW of PSUs to it would damage the wire.

[Uncle Peter]

There is passive and active. Passive probably only counteracts LC PF, not the harmonic one.

[Uncle Peter]

Cool, it's on wheels!

I take it the thing at the top is a cooling oil reserve?

[Uncle Peter]

Did he do that on purpose?

If a circuit breaker trips when it shouldn't, I replace it with a less sensitive one, or a fuse.