Led Halogen Drivers
- Thread starter anobium
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Do you have the information hat is printed on the component?
Just clarify we are talking about drivers or transformers.
Just clarify we are talking about drivers or transformers.
Excuse my ignorance, the supplier used the term driver, when I said transformer, I thought they were both one and the same.
I should have mentioned that the lights are on the underside of kitchen units and that each one has its own transformer/ driver to avoid unsightly wires being visible.
I have enclosed pics of the transformers/ drivers
Attachments
The LED lights will require the LED power supply, they are different from the halogen transformers.
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Not what I wanted to hear but many thanks for your kind advice.
The one on the left is a halogen lamp driver or power supply. It is NOT a transformer despite what it says on the cover. The one on the right is an LED driver or power supply as it says.
A transformer changes voltage or current by electromagnetic induction (one exception is a 1:1 isolating transformer which does not change voltage or current). A transformer supplies AC, LEDs require DC generally, though some have rectifiers built in so can work on AC.
Your supplier was ignorant and should have asked if you wanted a transformer or driver and explained the difference.
The OP asked the difference between a transformer and a driver. If you don't know yourself please don't criticise those that do.
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A transformer transforms something, this can be the earthing system, the voltage or the current, it can also transform current into voltage. But they in the electrical trade are wire wound devices with no electronics.
An electronic transformer is NOT a transformer, but replaces a transformer and does the same job, it often has a transformer inside and has the advantage of including some form of regulation so where used with quartz lamps it ensures the lamp is at the correct temperature. However they also have three major draw backs, one is they have with some odd exceptions a minimum output, and also work on high frequency which limits cable length, and the regulation may not be smooth enough to stop spikes damaging LED's.
A driver is DC and regulates the current rather than voltage, most LED's have drivers of some type built into the lamp package, this allows them to work on a set voltage, but some do required external drivers 320 mA seems to be a typical output, the voltage output will often vary typical 6 ~ 50 volt the LED's supplied from a driver are wired in series.
A power supply covers all of the above and there is also a voltage regulated DC power supply, where the supply is smoothed to a point OK for LED's but not really good enough for other uses, it is often called a driver, as with the electronic transformer this is a misleading name, as it is really not a driver, as said drivers are current regulated not voltage, however the lighting industry has historically swapped names around. They also call the electronic unit to power fluorescent lights a ballast where it is not really a ballast but a replacement for one.
So one has to ignore the name, and read the specifications instead, you need a fixed voltage of 12 volt, and no or very low minimum current a maximum current greater than the sum of all the lamps being powered from it. Watts is volts times amps times power factor correction, there is no power factor with DC, some power supplies give the rating as VA which is nearly the same as watts, but does not include the power factor correction. In the main one can consider VA and Watts being the same.
In theory if you have 4 x 7W LED's in parallel you should be able to use the 20 ~ 60 VA power supply, in practice it often produces spikes which could damage some LED's and also many when you read the full specifications state the extra low voltage output lead must be no longer than 1 meter which means in real terms you can't use it.
Pulse width modulated (PWM) and switch mode power supplies regulate the output by switching on and off, and varying the on time (called "Mark") and off time (called "Space") and correct output by altering the Mark/Space ratio, this can be before or after the transformer if it uses one. If before the transformer the transformer makes the output into nearly a sine wave so it can power LED's with no problem as long as they are designed for AC, however if after the transformer or if no transformer is used, then the output can damage LED packages. The LED package can have a PWM driver built in, or it can be a simple resistor, or with AC only a capacitor.
Please note 12 volt is Extra Low Voltage, 230 volt is Low Voltage, 50 volt AC and 75 volt DC is the dividing line between them.
The idea of 12 volt for quartz lamps was it allowed regulation, and thicker filaments so they could run hotter and lasted longer, with LED lamps all the advantages except for using in special locations like in the bath have gone. So better to change to low voltage (230 vac) and get rid of all the external transformers, drivers, and power supplies and use lamps with them all built in. Makes life a lot simpler. And I for one want a simple life.
I had a boss who had a plaque on the desk, it stated "These people who think they know it all, are especially annoying to those of us that do." I really loved that.
An electronic transformer is NOT a transformer, but replaces a transformer and does the same job, it often has a transformer inside and has the advantage of including some form of regulation so where used with quartz lamps it ensures the lamp is at the correct temperature. However they also have three major draw backs, one is they have with some odd exceptions a minimum output, and also work on high frequency which limits cable length, and the regulation may not be smooth enough to stop spikes damaging LED's.
A driver is DC and regulates the current rather than voltage, most LED's have drivers of some type built into the lamp package, this allows them to work on a set voltage, but some do required external drivers 320 mA seems to be a typical output, the voltage output will often vary typical 6 ~ 50 volt the LED's supplied from a driver are wired in series.
A power supply covers all of the above and there is also a voltage regulated DC power supply, where the supply is smoothed to a point OK for LED's but not really good enough for other uses, it is often called a driver, as with the electronic transformer this is a misleading name, as it is really not a driver, as said drivers are current regulated not voltage, however the lighting industry has historically swapped names around. They also call the electronic unit to power fluorescent lights a ballast where it is not really a ballast but a replacement for one.
So one has to ignore the name, and read the specifications instead, you need a fixed voltage of 12 volt, and no or very low minimum current a maximum current greater than the sum of all the lamps being powered from it. Watts is volts times amps times power factor correction, there is no power factor with DC, some power supplies give the rating as VA which is nearly the same as watts, but does not include the power factor correction. In the main one can consider VA and Watts being the same.
In theory if you have 4 x 7W LED's in parallel you should be able to use the 20 ~ 60 VA power supply, in practice it often produces spikes which could damage some LED's and also many when you read the full specifications state the extra low voltage output lead must be no longer than 1 meter which means in real terms you can't use it.
Pulse width modulated (PWM) and switch mode power supplies regulate the output by switching on and off, and varying the on time (called "Mark") and off time (called "Space") and correct output by altering the Mark/Space ratio, this can be before or after the transformer if it uses one. If before the transformer the transformer makes the output into nearly a sine wave so it can power LED's with no problem as long as they are designed for AC, however if after the transformer or if no transformer is used, then the output can damage LED packages. The LED package can have a PWM driver built in, or it can be a simple resistor, or with AC only a capacitor.
Please note 12 volt is Extra Low Voltage, 230 volt is Low Voltage, 50 volt AC and 75 volt DC is the dividing line between them.
The idea of 12 volt for quartz lamps was it allowed regulation, and thicker filaments so they could run hotter and lasted longer, with LED lamps all the advantages except for using in special locations like in the bath have gone. So better to change to low voltage (230 vac) and get rid of all the external transformers, drivers, and power supplies and use lamps with them all built in. Makes life a lot simpler. And I for one want a simple life.
I had a boss who had a plaque on the desk, it stated "These people who think they know it all, are especially annoying to those of us that do." I really loved that.
Very good post, except that I wouldn't agree that the so called electronic transformer does the same job as a transformer. It does this in one exception only, when supplying 12 volt halogen lamps.
It would not replace a transformer for instance when a elv AC supply was required for a small induction motor.
It would not replace a transformer for instance when a elv AC supply was required for a small induction motor.
Was wondering that myself...
It would, if it was designed for that purpose.
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The transformers used for aircraft ground lights have a set current all wired in series and these then have a volts output to work the light so every lamp has the same output. Also with a current transformer often the meter it drives is a volt meter rather than an ammeter. Yes rare, but it seemed everyone was out to select any point missed.
As it is "An electronic transformer is NOT a transformer, but replaces a transformer and does the same job." should have read "An electronic transformer is NOT a transformer, but replaces a transformer and does the same job, when used to power a quartz lamp." to me we should not still be arguing about when to call a spade a shovel.
But the English language is adapting, even in my life time, lorry and wagon seem to have been replaces with flat bed and tilt. Writing has been replaced with texting, and as to words like decimate, clearly deci refers to 10, and as a boy that mean to get rid of 1 in 10, today it seems to have reversed it's meaning to mean get rid of 9 in 10. CD was corps diplomatique not a compact disc, and PC was Police Constable but it seems that is no longer politically correct?
I was taught in the days of feet and inches, pounds and ounces, and we had pounds per square inch in our tyres. Never did I see a tyre pressure in slugs per square inch so why did it change to newtons?
As to kWh when I was at school energy was measured in Joules or Calories or calories I remember writing in my English lesson "calorie is the unit of energy, but where it would be a large number we use Calorie which is 1000 calories." just so I could start a sentence with a small c and get away with it. It seems wrong to use a unit with h for hour when it has no time in the unit. Since the watt is a joule per second and there are 3600 seconds in an hour there are 3600 joules in a watt/hour so 3600 kJ in a kWh so it is a smaller unit than kJ but just does not seem to be the right unit.
Next instead of signs saying 60 for 60 MPH we will have signs saying 88 for 88 feet per second.
As it is "An electronic transformer is NOT a transformer, but replaces a transformer and does the same job." should have read "An electronic transformer is NOT a transformer, but replaces a transformer and does the same job, when used to power a quartz lamp." to me we should not still be arguing about when to call a spade a shovel.
But the English language is adapting, even in my life time, lorry and wagon seem to have been replaces with flat bed and tilt. Writing has been replaced with texting, and as to words like decimate, clearly deci refers to 10, and as a boy that mean to get rid of 1 in 10, today it seems to have reversed it's meaning to mean get rid of 9 in 10. CD was corps diplomatique not a compact disc, and PC was Police Constable but it seems that is no longer politically correct?
I was taught in the days of feet and inches, pounds and ounces, and we had pounds per square inch in our tyres. Never did I see a tyre pressure in slugs per square inch so why did it change to newtons?
As to kWh when I was at school energy was measured in Joules or Calories or calories I remember writing in my English lesson "calorie is the unit of energy, but where it would be a large number we use Calorie which is 1000 calories." just so I could start a sentence with a small c and get away with it. It seems wrong to use a unit with h for hour when it has no time in the unit. Since the watt is a joule per second and there are 3600 seconds in an hour there are 3600 joules in a watt/hour so 3600 kJ in a kWh so it is a smaller unit than kJ but just does not seem to be the right unit.
Next instead of signs saying 60 for 60 MPH we will have signs saying 88 for 88 feet per second.
True, but it's not the transformer which is 'transforming current into voltage' but, rather, the load impedance (I believe known as 'the burden' in CT-speak!).
For a given primary current, the secondary of a CT behaves essentially as a constant current source - so that if one connects it to a load, the voltage across that load will be proportional to the secondary current (and hence also the primary current). As you know, that's why leaving the secondary of CT open-circuit can be dangerous/damaging, since the voltage tries to rise to 'infinitely high' (the CT equivalent of putting a short-circuit across the secondary of a 'voltage transformer', when the current attempts to rise to 'infinitely high')).
However, the CT itself 'transforms' one current into a different current.
Kind Regards, John
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