Power to your Mouse

 This morning, Friday Jan 15th 2016, on Radio 4 I heard that British consumers were getting ripped off. Nothing new of course since Maggie Thatcher began the process of selling off our assets. In most things we're getting ripped off but on the radio today a representative from the power industry was explaining that naturally, the industry was setting prices as high as possible. What's more he was from EoN...our supplier!!

The announcer explained that, although it was easy to switch one's gas and electricity supplier, mostly... people didn't bother.

How easy is it? Well, ages ago I tried to switch but was so confused over alternative deals I didn't bother. Of course, if you don't possess a computer, AND are reasonably adept at using it there's no chance you'll ever switch supplier AND be ripped off (despite the claims such as "Because keeping a promise matters" ... quote from EoN on the front of their booklet full of pictures of laughing people.. incidentally, on Page 2 of said booklet... Is the old guy smiling broadly, whilst on the phone, getting a much reduced quote from another supplier?)

As I mentioned, our supplier is EoN. It wasn't once upon a time, but our old supplier was bought out and EoN just took over. We used to have "Staywarm"... in fact, we were one of the first to sign up for the special deal offered to pensioners. The "Special Deal" lasted for only a short time because, naturally if you signed up to stay warm, then you stayed warm. Unmetered gas and electricity was a dream come true, especially when you liked to be warm. Gradually though the deal turned sour. The low quarterly price started to rapidly rise until it reflected the amount of gas and electricity you were actually using. Because it was still "unmetered", unless you actually used the amount predicted, you lost out. Hence you just used more and more and obviously the new annual prices got hiked up and up and up.

At last Staywarm was stopped.Our provider switched us to something supposed to be "equal in value". It wasn't easy to switch to another provider because one's consumption by that time was sky high and resulted in snotty remarks such as "we don't handle commercial users". So we stayed with EoN.

Today, I decided to switch... definitely. Because we'd opted not to receive paper bills, I had to log onto EoN's website to find our consumption. Not easy, but eventually after an email or two to find my user name and password, I was able to see my account details.

Incredibly confusing. Does "CR" mean I'm in the black or in the red (for example BT used "Credit" to mean you were in debt)? My monthly charges varied from £245 down to £36. My "credit", whatever that means, went from minus £220 to plus £1,255 over a couple of years. Consumption was based mainly on "Estimated" meter readings. My latest bill dated 4th Jan 2016 said I'd just paid £216 and the "credit" was £1,026. I went to read the meters. My "Estimated" electricity reading was nearly 1,200 units higher than the actual meter reading. No wonder I have loads of credit. EoN were misrepresenting my consumption by a huge amount. I'm acting as a banker to EoN and that's just not acceptable. But how much electricity and gas are we actually using? Before I can switch with confidence I need to discover the true amounts.

I downloaded the last eight bills. I couldn't get any more because the EoN website gave me error messages.

No help reading the bills though. Too many Estimated readings and stupid credit sums.

Let's try the meter readings. This was the answer because I was able to pinpoint two readings on the same day in consecutive years that were actual rather than estimated.

24th September 2015 and 24th September 2014 gave me 90,151 minus 81,655 or 8,496 KWh of electricity for 12 months, similarly the gas readings were 3362 minus 1551.

Now to convert the gas readings: Using the factors in the last bill I worked out that we'd used 20,264KWh of gas. Unless I've made a mistake this meant we'd used 8 megawatt hours of electricity and 20 megawatt hours of gas. So, armed with these numbers I ploughed on and tried two or three comparison websites. Interestingly the cheapest deals were from companies not signed up to the switch sites. Clearly, unless I'm misinterpreting something, it costs more if you switch to a provider that's signed up to a switching website....

Because we use the same provider for gas and electricity I tried this option first. I could save a predicted £606 per year. Bad idea though, because by splitting gas and electricity between two suppliers I was able to save over £700 per year.

I switched my gas to "Better Energy Supply Ltd" and electricity to "GB Energy Supply" for £700 savings.

Both will have organised switching in about 3 weeks. Let's see what happens...... Our broadband switchover was seamless...

Incidentally, in the above paragraphs I've used the word "supplier" but of course most of these companies are mainly billing agents for the main energy producers. A few of the choices actually produce electricity and (nowadays) pump natural gas down pipelines. The billing agents buy the products at wholesale prices and add a mark up, then try to confuse us with figures and exotic sounding energy plans. Hopefully, cross fingers, the confusion is managed by the switching websites. Now I'll need to remember two user names and two passwords...

December 2016.. of course it's obvious isn't it.. sooner or later one of the emerging billing agents cutting costs to the bone to gain more customers would come a cropper. I received an email telling me that my chosen , really cheap, electricity supplier had gone into liquidation and the powers that be were taking over and transferring my custom to someone new.

Now an event that took place 9th March 2019



 This is a view of my recently repaired Uninterruptible Power Supply.

The reason for using a UPS is to stop my computer from turning off by itself and possibly corrupting hard drive data if the mains fails. A UPS uses a set of lead acid batteries to produce a standby for the mains supply if the latter disappears.

I've had it now for several years and it always seems to work by switching to battery power on mains failure. It drives my computer and its display plus a desk lamp.

Mains is not very reliable in this part of the country. It's a lot better than it used to be when we had bare wires running down the lane and these were constantly being bashed by tree branches.

The mains still goes off fairly regularly though. Often the excuse is "a swan flew into the overhead cables" but I suspect that's not the only reason.

So why has it recently been repaired?

 Last Saturday I was watching the TV whilst waiting for my dinner. The time is a bit vague because I'd stopped and started the programme a few times, but let's say it was 7pm. Although it had been windy during the day it was now calm and not raining. Suddenly there was a sort of thud and it went dark and totally silent. I went to tell my wife the power had gone off, but she already knew as it had gone off in the kitchen as well. I poked my head into the office and saw the computer screen was lit and the computer was running properly. After a few minutes... before I found the torch and then our large supply of candles and matches, the power came back on accompanied by lots of bleeping noises from various things around the house and my laser printer struggling into life with its rollers running thinking something needed to be printed (it always does this after a power outage). I then trotted around setting things to right. The three Amazon thingies all going by the name "Alexa" needed to be unplugged and re--plugged because whoever wrote their software has never experienced a power cut. The Sky box was now pretending it was brand new and telling me how to navigate its menu. The hi-fi audio system needed to be brought out of standby and that was all. Of course we have a few clocks that needed resetting etc.

It must have been after another ten minutes or so when there was a power blip but everything bar the hi-fi amplifier stayed on. I switched it on and we continued eating our dinner. Then there was another blip and again I turned the sound back on. I'd been aware of a strange smell so trotted to the back door opened it and sniffed the air. Just the usual smoky smell from log fires (well we do live in the New Forest and many people take advantage of the proliferation of trees). I came back in and went into the kitchen. A slight smell of steam trains (not many will remember the days of British Rail and before that LMS, LNER etc, but the smell included a percentage of hydrogen sulphide from sulphur in the coal). I sniffed in the office and it was definitely stronger and then I noticed the computer screen was dark and waggling the mouse had no effect. The UPS screen was out and heat was emanating from its case. I unplugged the various cables and lifted it out.

The case was very hot. I removed the cover and felt the batteries.. both were too hot to touch so I unplugged their cables and removed them and noticed one had a hole in the top. This was the source of H2S.

As I've repaired several UPS equipments for customers I stripped the thing down and found nothing really serious. Thankfully the thing was (factory) fitted with a 5-amp fuse (although the UPS is rated at 1500VA the fuse rating will not permit a multiple of amps to flow 5x240=1200VA which is slightly puzzling but in retrospect a jolly good thing).

Often a bad UPS will have vaporised circuit tracks, burnt circuit board material and loads of soot everywhere, but mine looked pristine.

Inside the case there's not much to see. Two 12 volt 7Ah batteries, a huge mains transformer, and a small circuit board. There are two heatsinks and two sets of "TO220" power transistors. The key transistors are arranged in two sets of three to handle power to and from the batteries. They're all marked FP50N06 so are N type MOSFETs rated at 60 volts and 50 Amps, so are designed around a supply voltage of say 40 odd volts up to a maximum current of say 60 Amps. Transistor specs need scrutinising because their ratings are often quoted when their vital parts are say 25 degrees C and not close to melting point as sometimes imagined though ignorance. The heatsinks are pretty small so whatever amps flow, it shouldn't be for too long.

I checked my spares box and discovered several 50N06 transistors so unsoldered the three that showed as dead short and checked them on my Peak tester. Only two were bad so I fitted two new transistors and replaced the good one. Nothing else looked bad so I replaced the fuse and plugged it in. No problem.. it worked fine.. so I ordered two new batteries and the next day fitted these and the UPS was sorted out. It's now sitting in place driving this computer as I type (and pictured above).

Below... the old batteries.


 So what had happened you should ask? A rough and ready calculation can be done. The transistors that failed had a maximum voltage rating of 60 volts. The mains transformer input is marked 220 volts and the heavy secondary winding 18v -0-18v. The peak output from the transformer will be a nominal 50.9 volts (although this will be at around its rated load which is highly debateable... see later).

Assume an input mains voltage of 253 volts (that's 230 volts plus the legally allowed maximum of +10%). That peak output will rise to 58.54 volts. This figure is below the 60 volt transistor rating so ostensibly.. to blow up the transistors the mains voltage would need to be in excess of the legal maximum of 253 volts. Let's say 260 volts.. that gives 60.1 volts so maybe that's the reason for the UPS failure? A high mains voltage short-circuited the 50N06 transistors which allowed 36 volts of AC to be applied acoss the two 12 volt batteries (= nominally 26.4 volts). This resulted in excessive current, lots of heating, shorted plates, and destruction.

What did Scottish & Southern Electric have to say? Loss of an overhead wire from a swan collision. But I don't buy that explanation for my power cut because it took surely more than the few minutes it took for my power outage to repair the fault? The explanation is to do with switching. If switchgear is used to reassign cables and transformers to lessen the original impact of the fault it should have operated within the legal framework which specifies 230 volts -6%, +10%.

In the end my UPS is running again and I'm promised a cheque for £40 to cover my repair. I wonder how many minutes the boss of Scottish & Southern has to work for £40? Probably something like 2 minutes?

 Just a thought on VA rating. Most technical people would interpret a VA rating to be RMS but alas, in order to sell stuff it's not uncommon to mislead with ratings. For example a peak rating rather than an RMS rating will roughly gain an extra 50% in terms of numbers. If the factory fits a 5 Amp fuse when the rating is 1500VA this means 1500 divided by the mains voltage. If the transformer primary is marked 220 volts it will draw 7.5 Amps RMS and the 5 Amp fuse should blow. If the 1500 VA rating is peak rather than RMS the current will be 4.8 Amps RMS. This is pretty close to the fuse rating of 5 Amps so it may be the case that my UPS is really a 1000VA equipment not a 1500VA.

The explanation is supported by scrutiny of the Powercool datasheet. The "Model" is "1500VA" but the rating is "900Watts". 900Watts from 240 volt mains requires a fuse of 3.75Amps. Forget about 1500VA... my UPS is rated at 900Watts which explains why it was a lot cheaper than others having the same quoted ratings.

What about my mains voltage? The display on the UPS gives a voltage reading every second and as I watch it at 11:30am it mainly read around 235 volts but then dropping to 231 volts then after a few seconds 252 volts before dropping back to around 235 volts.


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