Proportional Controller Technologies

[solar warrrior]

Gavin

Plenty of others narked with them too for selling so many of their dubious units when there are better products available. There are some phase controlled units that are well filtered so are compliant despite what some may claim here. Greenologic http://www.greenologic.co.uk/SharedFiles/Download.aspx?pageid=176&mid=258&fileid=90 state that with filtering it is possible. Mind you there are other phase controlled products that have little/no filtering and so should not be sold. One I have seen has no more than one small snubber capacitor on its output to provide filtering. Useless.

I would have thought the majority of houses have too much impedance to use an Immersun on although suspect that many are close enough that no one notices the flicker unless it is pointed out to them, even though technically there is more flicker than allowed. What proportion of houses do you think it is not legal in? Lots of posts here about Immersun and flicker and they have never tried to defend themselves as far as I can see because it is indefensible.

I wonder if that buzzing MCB was one of the ones that should have been recalled a couple of years ago but was still installed. I forget the details but a major supplier recalled a large batch of them.

One thing Greenologic do not mention is PWM also gives out considerable EMI. But it is of such a high frequency that it can be suppressed by screening the cable between the controller and the immersion. That is added expense and imagine having to recable a long route to the immersion with screened cables. At least that is what the EMMA people have found I believe on their PWM system. It is all adding up to quite an expensive solution???

 

[Gavin A]

I'd suspect it'd be more to the point to ask what proportion are actually fully compliant based on the grid impedance - the one we first hit problems with showed almost a 1V drop per kW of load, vs a 0.7V total limit under the flicker regulations (IIRC) - ie it was around 3,5 x outside the limit.

To comply for a 3kW immersion there'd need to be less than a 0.25V drop per kW of load, which I doubt applies in more than maybe 10-20% of cases close to big transformers, with chunky cabling used. I'd expect that maybe 50% or so are close enough to not really be an issue, 20-30% starting to become slightly noticeable, 10% definitely noticeable if you look for it, and 10% increasingly problematic... I think it's been masked because most solar PV adopters will also have led or CFL lights, which don't suffer flicker issues, so won't notice - but their neighbors might have halogens / filaments, and be experiencing flicker issues but not knowing why or who to complain to.

Figures are just guesstimates, but I'd think they'd be roughly in the right ball park

 

[solar warrrior]

Earlier this year an Immersun was measured against the flicker spec and failed by a margin of 4.5 on a long term (2 hrs) test and 6.7 in short term (10mins). Does your 0.25V allow for this?

My house has a 0.7V drop per kW and a different burst fire device I tried induced a lot of flicker. The few people I personally know who have tried burst fire devices of home built origin have all had flicker with 2 resulting in complaints from neighbours.

 

[pwboston]

Re: Propotional Controller Technologies

Installed Immersun the other week customer complaining that all the lights flicker when immersun is being used. Apparently one of the side effects of this device.

are we saying that it has this issue during the daytime only, ie when actually being sent to the immersion heater.

We have installed a few (I have 1) but havent noticed any issues (yet)

 

[Gavin A]

Earlier this year an Immersun was measured against the flicker spec and failed by a margin of 4.5 on a long term (2 hrs) test and 6.7 in short term (10mins). Does your 0.25V allow for this?

My house has a 0.7V drop per kW and a different burst fire device I tried induced a lot of flicker. The few people I personally know who have tried burst fire devices of home built origin have all had flicker with 2 resulting in complaints from neighbours.

yes - well roughly speaking, IIRC the limit is 0.7V fluctuation, so 3 x 0.25V = 0.75V, which is why I said less than 0.25V per kW.

The problem with testing this is that the voltage fluctuation depends entirely on the impedance of the local grid supply, so anyone testing this in a factory environment on an industrial estate will get an entirely misleading impression of the situation when the unit is installed in domestic situations. Conversely I'd assume you must have been doing the testing in a situation with a fairly high grid impedance to get those results.

But a brief analysis of the theory would really be all it takes to conclude that there's no way units using basic burst fire technology should be controlling the power to 3kW loads in domestic situations - at least not without an analysis of the grid impedance beforehand to confirm suitability.

btw, I'm aware the flicker regulations are a little more complex than this, with the volt swing allowed varying with the frequency, but I think it's roughly true that 0.7V is the maximum allowable for a unit that has the capacity to have the burst fire operating at every other cycle, so worst case scenario needs to be used.

 

[echase]

A statement from Greenologic has just been officially released so I am now allowed to distribute this document that might also be of interest

The published links favour one particular product whilst casting doubt on all the others. E.g. it is trying to claim that all apart from PWM ones have no Lab Conformity Certification whereas theirs does. That might be true of some/many but what evidence have they used? For instance our own product is tested and certified but is conveniently for them left off their comparison table. Were they worried that it would show up their case in favour of PWM? I am not doubting the potential of PWM for interference free operation but the products are probably expensive.

 

[danesol]

Gavin

Plenty of others narked with them too for selling so many of their dubious units when there are better products available. There are some phase controlled units that are well filtered so are compliant despite what some may claim here. Greenologic http://www.greenologic.co.uk/SharedFiles/Download.aspx?pageid=176&mid=258&fileid=90 state that with filtering it is possible. Mind you there are other phase controlled products that have little/no filtering and so should not be sold. One I have seen has no more than one small snubber capacitor on its output to provide filtering. Useless.

I would have thought the majority of houses have too much impedance to use an Immersun on although suspect that many are close enough that no one notices the flicker unless it is pointed out to them, even though technically there is more flicker than allowed. What proportion of houses do you think it is not legal in? Lots of posts here about Immersun and flicker and they have never tried to defend themselves as far as I can see because it is indefensible.

I wonder if that buzzing MCB was one of the ones that should have been recalled a couple of years ago but was still installed. I forget the details but a major supplier recalled a large batch of them.

One thing Greenologic do not mention is PWM also gives out considerable EMI. But it is of such a high frequency that it can be suppressed by screening the cable between the controller and the immersion. That is added expense and imagine having to recable a long route to the immersion with screened cables. At least that is what the EMMA people have found I believe on their PWM system. It is all adding up to quite an expensive solution???

When you say a MCB is/was buzzing - why does it do that as my SMA Inverter is often heard buzzing at high power generation - is this the same kind of thing ?