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Chat => Tech Chat => Topic started by: sheddyian on February 25, 2015, 11:32:30 PM
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Hi all,
I've been busy of late, so not been tinkering in the shed as much as usual, but something came up the other day.
I had a solar panel salesman round, selling a system to generate electricity (I'd be quids in, apparently :-X ).
As part of his speil, he looked at my electricity bill, and sucked through his teeth, saying how high it was. Salesman patter to make you want to reduce it by buying something that he just happens to be selling. But actually, I did think it was high, and it did make me want to do something about it.
For a few years I've had one of those electricity monitors that sit on a table or shelf. It's got an LCD screen, and there's a wireless sensor that you clamp around the live cable going into your fuse box. The remote display then shows you how many watts you're using in realtime, and also draws a very basic graph and some stats. I got it for free from British Gas a few years ago.
But watching the numbers jump about isn't that useful, what I'd like to do is plot them.
Turns out this is rather easy to do, with a Raspberry Pi and a ready-produced setup to do just that.
The energy monitor (mine is a Current Cost model 128) has an RJ12 serial port on the back which spews out data! I bought a data cable for it off ebay that has a USB adaptor at the other end.
You can download a ready-to-use Raspberry Pi image from here http://lalelunet.github.io/measureit/ (http://lalelunet.github.io/measureit/) which has the MeasureIt software already installed, plug the Raspberry Pi into the energy monitor, switch it all on and off it goes.
The software records all the data in an SQL database, and you can view the graphs and configure it through it's web interface - just point your browser at the ip address of the Raspberry Pi.
It's all rather neat, and I'm very impressed.
I've attached a graph plot for this evening, you can easily see the moment I switched the electric heater off in the shed and came indoors, and you can also see there's quite a high background consumption going on that needs to be looked at.
I thought I'd share this with you all here as I'm fascinated by it all, and I know others here like plotting DSL line data, now you can plot other things too, and chase around trying to improve the graph :lol:
Ian
[EDIT : On the graph, the left hand vertical scale is Watts, and horizontal scale is time (GMT)]
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That's really interesting. Thanks for bringing it up. I might get one of those myself.
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and if you dont have a raspberry (like me :( ) you can use the meter (mines was a present from E o N) with a PC. Various software can be found here http://currentcost.com/software-downloads.html (http://currentcost.com/software-downloads.html) If memory serves the software supplied was branded and a bit rubbish.
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Likewise I inherited a BG one a few years but within a few months renamed it 'The Worry Meter' because initially every time I looked at it I would start worrying about the power I was using and trying to decide what could be turned off, but I will admit it did get me thinking and made me start turning things off at the wall, such as with the TV cable box' being turned on and not used for about 18 hours a day but still consuming 30 watts, but never got down to downloading any software.
So if the software is installed how does the software update if the computer is turned off?
Or is there some memory in the Current Cost meter which just updates when the computer is turned on?
The newer versions of these now have a battery built into them so for short periods 'maybe a couple of hours' they can be unplugged but still display it's usage details, but unfortunately EON are only giving them away to their customers with SMART meters installed.
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So if the software is installed how does the software update if the computer is turned off?
Or is there some memory in the Current Cost meter which just updates when the computer is turned on?
In my case, I have the Current Cost meter connected to the Raspberry Pi which is running 24/7. As it's a very low power computer (around one watt at 240 volt) it's not a significant extra load, though of course running a PC to do the same is going to use significantly more.
My meter is an earlier model that doesn't have any storage, it is just streaming the data from it's serial port in realtime.
I don't know if any of the newer, more advanced models can store data or not.
I was like you and initially used the Current Cost meter just to be surprised at how much background consumption there was, and to start identifying it - which is entirely the point of the things.
Ian
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Thanks Ian.
I was just over on the current cost site trying to find the information but still no real luck.
I think I did read 'a long time ago' that the newer models had a storage facility because with some of them you can go back in time for days or weeks but I don't know for how long.
However, just as a point of interest, trying to save energy is costing me a fortune with gadgets I have bought, such as, 3 sets (11) remote controlled 13amp socket outlet adaptors which have a brilliant range so I can turn things on and off even upstairs when I'm still downstairs probably about £25 in total, also 2off current monitoring devices which lets me know how much individual items are using and costing at £18.
1off 30watt LED flood lamp to replace my old 150watt and 2off PIRs to go with it so another £25.
Not forgetting 3off 5watt LED lamps which as it turned out I ordered the wrong colour so not being used but will end up in table lamps with timers for when I'm away on holiday.
But the point is, the only people who are saving are the government with their climate saving ideas, certainly not me, because I doubt if I would ever re-coup the cost of all the gadgets I have bought to monitor the energy I will be saving, and as for monthly/quarterly bills, the saving again has not really amounted to very much.
Which is something I can't say as with my new gas boiler, because the difference in gas consumption has dropped drastically compared with my old one which was only 14 years old and serviced every year.
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trying to save energy is costing me a fortune
Dont forget the cost saving isn't just in energy usage. Quality LED lights should last significantly longer before failure than candecent lights. So your saving money on replacements plus the karma you get from knowing you are doing your bit to reduce enviromental impacts. ;)
Interestingly, when I started using LED lighting in the home some years ago my thinking was "they produce little if any heat" and should last "at least 35,000 hours, 12 years based on use of 8 hours per day". This is not strictly correct.
They do produce a far amount of heat, hence the ally heatsink. This coupled with no guidance on fitting, such as the type of enclosure they are mounted in, ie the amount of free air surrounding them, can have a negative impact on there life, such as the drivers (voltage convertor) can fail quickly from de-soldering or thermal breakdown of components, or the LED's them selfs can fail.
Thankfully armed with a bag of replacement LED's and my soldering iron all the ones I have bought in the past are easily repaired.
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I found using a semi-decent powermeter (Brennenstuhl IIRC) of much more use than something providing an instantaneous reading of total power consumption.
I tried one of the current clamp wireless meters years back & I reckon it was accurate to within maybe 100W - certainly if total current draw for the house was < 1A then the accuracy left an awful lot to be desired.
So I bought a couple of the aforementioned powermeters (£15 each) and set them up - they'll calculate total power consumed/cost (variable rates) & also have some nice stuff like PF/W/VA for checking how inductive the load is if you "tinker" with stuff ;) Basically you plug them into a socket & plug in whatever you want to check.
From those I discovered that an old freezer was actually drawing a minimum of 100W, more usually 200W so replacing the freezer paid for itself inside 5 years. Similar story with AV/computing equipment - replacing the server was expensive but has paid for itself in the last 4 years. Likewise the battery in the UPS wasn't holding charge that well so the UPS was pulling a lot more power than it should - battery change cost £100 or so (1500VA UPS) but I should recoup that before it needs replacement.
A good deal more low-tech but it gets all the "low-hanging fruit" in terms of reducing power consumption - by that I mean the stuff which would make sense to change before it fails assuming you have the funds to do so.
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I found using a semi-decent powermeter........
Sounds the same as the 2 I bought, the reason I bought 2 was to be able to play around with one whilst the other was left in situe for a period of time of maybe a month at a time so as to give me a mean-average, or I suppose you could say more of a accurate figure of what was actually being used over the period, because don't forget some or most things go into a hibernation stage at some point or other if not being used, such as printers etc, but also another good thing with it, even though it's plugged in and turned on, it only registers the actual usage period and not for arguments show it being used for 30 days.
Whilst on the subject of LEDs, the rating on almost every LED is not the actual running rating because the manufacturers do not publish what the 'choke' uses to run the lamp, most small lamps are a extra 1 to 2 watts, so a 5 watt LED could actually run at 7 watts, yes very sneaky of the manufacturers to make them look more efficient than what they actually are, and that has also been confirmed from one of the UK's largest electrical wholesalers.
As for saving the environment, I'm not sorry to say, but I gave up on that a long time ago when I discovered what saving the environment was actually costing me.
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Its not a choke in mains voltage LED lamps, its a transformer & bridge rectifier to produce a rough 12V dc supply. The LED lamps I buy have total wattage listed (not just watts x number of LEDs) and so do the B&Q own brand however the branded stuff varies.
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Whilst on the subject of LEDs, the rating on almost every LED is not the actual running rating because the manufacturers do not publish what the 'choke' uses to run the lamp, most small lamps are a extra 1 to 2 watts, so a 5 watt LED could actually run at 7 watts, yes very sneaky of the manufacturers to make them look more efficient than what they actually are, and that has also been confirmed from one of the UK's largest electrical wholesalers.
You had me worried there, but doesn't seem to apply to some 7W bulbs I bought recently, probably from Costco.
The packaging actually specifies 'energy' with an EU flag at the top, expressed as '7kWh per 1000 hours'. That strongly suggests to me that total consumption is 7W, exactly as advertised, though it seems a pretty bizarre way of expressing it! :D
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Whilst on the subject of LEDs, the rating on almost every LED is not the actual running rating because the manufacturers do not publish what the 'choke' uses to run the lamp, most small lamps are a extra 1 to 2 watts, so a 5 watt LED could actually run at 7 watts, yes very sneaky of the manufacturers to make them look more efficient than what they actually are, and that has also been confirmed from one of the UK's largest electrical wholesalers.
You had me worried there, but doesn't seem to apply to some 7W bulbs I bought recently, probably from Costco.
The packaging actually specifies 'energy' with an EU flag at the top, expressed as '7kWh per 1000 hours'. That strongly suggests to me that total consumption is 7W, exactly as advertised, though it seems a pretty bizarre way of expressing it! :D
I know it's maybe only one watt, but you may find your 7w bulb actually consumes 8watt, as said earlier, this was also confirmed by a wholesaler who product do take into account the total running value and therefore seem to consume more than some of their rivals.
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What power factor do they run at?
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Whilst on the subject of LEDs, the rating on almost every LED is not the actual running rating because the manufacturers do not publish what the 'choke' uses to run the lamp, most small lamps are a extra 1 to 2 watts, so a 5 watt LED could actually run at 7 watts, yes very sneaky of the manufacturers to make them look more efficient than what they actually are, and that has also been confirmed from one of the UK's largest electrical wholesalers.
You had me worried there, but doesn't seem to apply to some 7W bulbs I bought recently, probably from Costco.
The packaging actually specifies 'energy' with an EU flag at the top, expressed as '7kWh per 1000 hours'. That strongly suggests to me that total consumption is 7W, exactly as advertised, though it seems a pretty bizarre way of expressing it! :D
I know it's maybe only one watt, but you may find your 7w bulb actually consumes 8watt, as said earlier, this was also confirmed by a wholesaler who product do take into account the total running value and therefore seem to consume more than some of their rivals.
I doubt if it is any watts at all, else the EU energy rating would be a direct lie. I can believe they might sometimes be vague, but a direct lie would surprise me.
Can you provide a reference to the source of your figures ?
What power factor do they run at?
Power factor is not stated, though the 7W bulb is marked '60mA'. That might suggest a very poor power factor or more likely is just the peak startup current.
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Can you provide a reference to the source of your figures ?
From the wholesalers conversation the answer is no, but from the 3off LED lamps I purchase that state 5 watts, when connected to two different brands of energy monitoring devices they both read 6 watts, and as for my 30 watt LED flood lamp 'with the PIR removed', when monitored registers 32 watts.
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Just wondering if someone could perform the experiment with one LED "bulb" and two DMMs -- one in series with the device and the other in parallel -- measuring current and voltage? :-\
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Just as a matter of interest if anyone is interested, I recently saw Digital Multi Metres over on Ebay for under £3 inc P&P
http://www.ebay.co.uk/itm/Mini-Electric-AC-DC-OHM-Voltmeter-Ammeter-Multimeter-Meter-Multi-Tester-MF-110A-/400797651822?pt=LH_DefaultDomain_3&hash=item5d5166d36e
In fact it looks the same type as the one that has been in my tool box for about 15 years.
Edit:
link changed
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Just wondering if someone could perform the experiment with one LED "bulb" and two DMMs -- one in series with the device and the other in parallel -- measuring current and voltage? :-\
That would only tell us the VA, not the power. Hence why c6em's question re PF. Would still be of interest, mind. :)
Worth stressing above all though, since the demise of 'proper' light bulbs, I pay more interest to the luminous flux, expressed in lm, regardless of wattage.
Another important parameter, largely unique to LED bulbs, is the beam angle, which is often quite narrow. Many LEDs contrive to 'throw' all the light forwards, away from the base. For a downwards hanging pendant that may be well as it shines onto the floor and walls but, for an upward facing bulb on an external wall lantern, it just lights up the sky. >:(
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That was the problem with the ones I bought, they were 6000lm +/- and just far to 'white' whereas the 2300lm (also listed as either cool-white or warm-white) give a much warmer looking light.
If no one else offers up the PF, then I will do it tomorrow with one of the 5watt LED lamps I have, but as said in my post above my multi metre is well past it's sell by-date and I wouldn't rely on it's accuracy for such fine readings so will not be offering to do that.
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My reason for asking the pf...
The current taken will depend on the VA rather than the Watts
It is the current squared which is the loss/heat maker in transmission and generation.
So VA is of more interest than watts to generators of power and it will always be larger than Watts.
A 50 MW generator would typically be specified as operating at 0.8 or 0.85 power factor.
Indeed there are some exotic stuff that runs at zero power factor - so the KW is zero but I can assure you the current certainly is not. So a KW meter would read zero while a VA meter would read the true 'VA power' being used.
If we are moving towards a point where the aggregate domestic consumption is at a power factor significantly less than 1 - then we could see domestic electric meter and charging policies changing such that it is metered by KVAhr used and not KWhr....as being a more accurate reflection of the current being drawn.
This is indeed how the big industrial user have been charged for umpteen years.
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That was the problem with the ones I bought, they were 6000lm +/- and just far to 'white' whereas the 2300lm (also listed as either cool-white or warm-white) give a much warmer looking light.
If no one else offers up the PF, then I will do it tomorrow with one of the 5watt LED lamps I have, but as said in my post above my multi metre is well past it's sell by-date and I wouldn't rely on it's accuracy for such fine readings so will not be offering to do that.
Colour is a separate measurement from lm.
If your energy monitoring devices are half decent they will probably be switchable between 'VA' and 'watts'. Mine are.
I would strongly recommend not attempting to measure mains current and voltage unless you really know what you are doing, and are qualified. I have a BSc in Electronics & Electrical Engineering. But that was a while ago, and even with my Uni' degree still I'd think long and hard before going anywhere near mains voltages with my own DMMs.... :o
Note for example I am not volunteering here, even though I have plentiful test equipment. ;)
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So VA is of more interest than watts to generators of power...
Agreed, wholeheartedly.
But watts are what we are billed for, or more accurately watts integrated with time, ie energy, or Watt Hours.
A low power factor is bad for the environment and bad for the supplier's bank balance. But the end-user consumer, assuming he has no real interest in the Power Company's well being, can smile smugly and disregard the VA, as he pays just for the Watt Hours.
In any case, OF is discussing Watts here, not VA.
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In any case, OF is discussing Watts here, not VA.
Very true.
However just to point out, I started work in 1964 as a apprentice electrician and worked most of my time as a electrician and mainly running my own very successful company, although as with most things in life, the grass always looked greener on the other side so I did deviate a few times from my chosen profession, but always ended up returning to the job I knew and did best.
Colour is a separate measurement from lm.
Yes I was just trying to point out to anyone who was interested that the colour 'lm' can be a very important factor when deciding which lamp to buy.
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But the end-user consumer, assuming he has no real interest in the Power Company's well being, can smile smugly and disregard the VA, as he pays just for the Watt Hours.
You may pay for watts but you can't disregard VA (PF) as you'll find most switches have a far lower current rating when dealing with inductive loads.
They have a tendency to weld themselves closed when you exceed 500VA at a PF of 0.7-0.8 - you'll usually find a seperate inductive load rating in the (very) small print.
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I plugged one of these 7W leds into a table lamp, fed from my power monitor.
The monitor has a crude resolution of 1W, no fractions. It alternates occasionally, between 6W and 7W, thus suggesting that the bulb's 7W rating is probably spot on.
Switched to VA it reads 12VA, thus suggesting that the marked 60mA may be steady-state after all, with a pf of circa 0.5-0.6.
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You may pay for watts but you can't disregard VA (PF) as you'll find most switches have a far lower current rating when dealing with inductive loads.
They have a tendency to weld themselves closed when you exceed 500VA at a PF of 0.7-0.8 - you'll usually find a seperate inductive load rating in the (very) small print.
Or at least, a disclaimer 'do not use with inductive loads'.
My favourite was a plugin timer switch, that I came across in Tesco a while ago, I planned to use it to make Dad's flat look 'occupied' when it wasn't. It called itself something like a 'Super Green Timer Switch', and was displayed in bright green packaging. It was so green in fact, I nearly decided to buy one for all my friends... until I read the small print, 'not for use with energy saving bulbs'. :D
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I looked in all of the "high street" DIY/electrical places around here and not one timer switch was rated at over 2A inductive (most were 1A). In terms of CFLs the timers don't like the start-up surge which fluorescent lighting has.
Edit - the workaround I use for inductive loads is to use a timer/switch to switch a relay on. Much easier to find relays which cope with inductive/capacitive loads than it is to find switches, strange old world at times :)
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One device I'd like to find is a combined timer and dusk/dawn switch. There are plenty for sale, but the 'timer' part just refers to the on-time.
In my case, it's for the garage wall lantern and I want it on after dark but no matter what time it comes on I want it off again around than 11pm, to avoid annoying the neighbours (and myself). And of course, it wants suitable IP rating.
You would think that would be a common enough want, but I have been unsuccessful. Currently have a timer inside the garage, and separate daylight sensor outside.