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Topic: Help Please Urgent Advice on low energy bulb smash amongst food etc.
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David Pannell
Phenomenal Film Handler
Posts: 1072
From: Horsham, West Sussex, UK
Registered: Nov 2004
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posted March 12, 2008 12:26 PM
You know, this is very much like the global warming syndrome. Unfortunately, nobody listens to the minority who are usually right, - just like the Appollo 11 warning!
Recent research has shown that the earth is geting warmer, but not because of what man is doing, but because we are still coming out of the last ice age. Methane and CO2 produced by cattle and natural forestation and vegitation far outweighs anything that man could ever produce even if he had all pollutants known at his disposal.
I am not politically biased, and this is not a political statement, but a scientific fact. Unfortunately, politics have distorted the facts and everyone wants to jump on the bandwagon.
Being an engineer and physics scientist, it just makes my blood boil when people can only get funding for a project if they say it's global warming related! What an absolute waste!
Anyway, back to the question at hand. The so-called energy efficient lamps are another mis-noma. Because they create such a poor power factor and distort the waveform of the electrical supply, your domestic meter can't read it accurately. So although you may be paying less, the electricity companies have to supply the extra current to compensate!
Hopefully, one day someone will wake up to all these cons by which we are surrounded.
I rest my case; and I sincerely hope I haven't offended anyone.
If our moderators feel I have been too demonstrative, please feel free to delete this post.
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Dave.
Valves and celluloid - a great combination!
Early technology rules OK!
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David Pannell
Phenomenal Film Handler
Posts: 1072
From: Horsham, West Sussex, UK
Registered: Nov 2004
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posted March 13, 2008 04:22 PM
Hi Tony,
Yes, I am happy to explain as best and as simply as I can, but one has to recognise that a technical explanation of this nature will inevitably involve some AC electrical theory; albeit fairly basic.
I think that under the circumstances, it is best if I e-mail you, as the Forum is probably not the correct vehicle for correspondence of this nature. Please let me have your e-mail address.
If, by reading this, the Moderators think a subject of this nature might be of sufficient interest to a wider audience, then I will be happy to post a thread on the Forum, but it will be quite a lengthy article!
Best regards,
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Dave.
Valves and celluloid - a great combination!
Early technology rules OK!
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David Pannell
Phenomenal Film Handler
Posts: 1072
From: Horsham, West Sussex, UK
Registered: Nov 2004
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posted March 14, 2008 04:02 AM
OK!
Due to popular demand, here is an explanation which I hope everyone will be able to understand. I apologise in advance to any other qualified electrical engineers or physicists who may feel patronised.
In a DC circuit, watts = amps x volts. A very simple calculation.
However, in an AC circuit, things are vastly different. Because the voltage is fluctuating, or alternating between +ve and –ve, so is the current (amps).
Different types of utilisation equipment handle this alternating current in two fundamentally different ways. If the load is purely resistive, eg. an incandescent lamp, heater or cooker etc., the calculation is simple, as in the case of DC.
This is usually far from the case, though, as loads tend to be either inductive or capacitive.
Inductive loads comprise such things as motors and transformers, or equipment comprising coils of wire, if you will; whereas capacitive loads comprise equipment which is used for charging banks of capacitors for many different applications. Amongst these are fluorescent lamps which have capacitors in them for striking the gas and ionising the plasma.
When an AC supply is connected to an inductive load, the voltage appears across the load immediately and the current through the device builds gradually. The current is said to lag the voltage by a number of degrees, depending on the value of inductance of the load.
Conversely, when an AC supply is connected to a capacitive load, the current flows immediately, and the voltage across it builds gradually (as the capacitor charges up). The current is said to lead the voltage by a number of degrees, depending on the value of the capacitance of the load.
The power factor is the cosine of the number of degrees by which the current leads or lags the voltage. Therefore in an AC circuit, watts = amps x volts x power factor (pf)
Thus it can be seen that if the power factor is 1 (unity), then watts = amps x volts, as both current and voltage are in phase, but this can only occur in a purely resistive load.
If the current and voltage are out of phase by as much as 90°, for example, then we have what is termed a “wattless current” as the cosine (cos) of 90° is zero. (Remember your maths tables at school - sines, cosines, radians and tangents, etc.)?
Here is the very nub of the matter. For all values other than a unity pf, current is being wasted. The electricity supply companies have to provide a larger amount of current than is actually required to drive the equipment. This additional current also has to be generated, distributed, etc., but we are getting nothing for it. Also, larger cables are required to carry this extra current, which additionally subjects switchgear, and associated equipment to greater stresses than they were designed for, or than would otherwise be necessary. This all leads to additional energy which has to come from somewhere.
The answer is to bring the pf back to something approaching unity, where the phase angle between current and voltage becomes zero, (as cos 0 = 1). In the case of inductive loads, this is achieved by connecting capacitors to the load, which as we have seen, have the reverse effect of inductive loads such as motors.
Similarly, in the case of capacitive loads, this is achieved by connecting inductances to the load, which again, as we have seen, have the reverse effect of capacitive loads, such as fluorescent lights.
However, it is extremely difficult to achieve a pf of unity in practical terms, as loads are continually changing. Therefore the Electricity Supply Industry Authority in the UK has settled on a figure of 0.928 as achievable.
Special equipment and instruments are required to measure these values of so called wattless currents, or reactive power, to give it its correct name, which is either inductive reactance for any equipment with a 'coil of wire in it', or capacitive reactance for any equipment with a capacitor in it.
Domestic meters only read the watts (amps x volts) multiplied by time. They do not take into account the power factor. Thus we get watt-hours, or kilowatt-hours as a measure of electricity consumption. This is what we pay for. Thus it can easily be seen that by using low energy lamps of the fluorescent type, the meter will only read the so called 'apparent power' and not take into account the reactive power or 'wattless current'.
Therefore, although our electricity bill will definitely be lower by using these lamps - no question about that - it is really false economy as far as energy production is concerned.
Fluorescent lamps, along with all IT equipment are also responsible for another electrical problem for the supply industry.
Harmonics.
Harmonics are multiples of the supply frequency.
When electrical or electronic equipment has a complex array of components, such as switch-mode power supplies, inverters, converters, inductances and/or capacitors, and so forth, a resonance is generated in the electrical supply, and again, there are limits imposed by the supply authorities for each harmonic up to the 50th. Limits for harmonics are set out in the G.5/4 Standard. A recent report in one of the scientific journals stated that hotels are the worst culprits by switching over to these low-energy lamps, and are causing the electricity supply companies major, major headaches.
Harmonic analysis is far and away beyond the scope of this discussion and is extremely complex, involving Fourier Analysis methodology and so forth.
The point of raising it here, though, is to state that harmonics also encourage false electricity meter readings.
So there you have it. It is really up to the individuals to decide for themselves.
If you've managed to get this far, thank you for your patience. I hope I have explained it understandably. I really don't see how I could do it any more simply.
I am somewhat embarrassed in writing an article of this sort for the Forum, as it is not in my nature to express anything other than humility when discussing scientific matters. However, on this occasion I do feel justified in letting the Membership know that I do speak with some authority on these matters, holding membership of the following professional institutions:
The Institute of Engineering and Technology (formerly the IEE) (UK)
The Institute of Physics and Physical Society (UK)
The Institution of Electrical and Electronic Engineers (USA)
The American Institute of Physics and Physical Society (USA)
and an invited member of The New York Academy of Sciences (USA)
With best regards to all,
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Dave.
Valves and celluloid - a great combination!
Early technology rules OK!
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David Pannell
Phenomenal Film Handler
Posts: 1072
From: Horsham, West Sussex, UK
Registered: Nov 2004
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posted March 14, 2008 09:49 AM
Hi Steve,
Yes, I did try to keep it ultra simple, bearing in mind that with respect, not everyone on the Forum is as conversant with power engineering as we happen to be.
As with all things of a technical nature, there is, of course, a trade off, but just where the crossover point is, remains to be determined by detailed measurement and calculation of the particular circuit and associated network in question.
You could well be right with certain aspects of your observation, but again, it all comes down to the accuracy of interpretation as to what exactly is going on in the system.
Even here in the UK, I know of several cases where judicious account of particular situations has not been caken into account or calculated correctly, with some so called consultants arbitrarily deciding to add a few capacitors here, or a few detuned reactors there in the hopes of curing the problem. Disaster usually ensues.
I'm sure we could go on all day, discussing various methods and scenarios, but as interesting as it may be to you and me, I think we ought to call it a day as far as detailed analysis is concerned.
After all, it was only really my intention to throw a little light for the uninitiated in really basic layman's terms. I hope you understand.
--------------------
Dave.
Valves and celluloid - a great combination!
Early technology rules OK!
| IP: Logged
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Jean-Marc is right! The amount of pollutants in city air is far greater than a vapor from a small broken bulb in a room. I think the broken glass is the real aggrivation here. ![[Smile]](smile.gif)
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and not a cloud in site, tonight we are looking west towards the "Southern Alps" and there is a brilliant sunset later on all the stars will come out. 
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