110V bulbs on Festoon Lighting

[Forestlands]

Found ordinary energy saving bulbs dimmed after a short time so purchased LED energy saving bulbs. Arrived today, checked them and found they could be used with a range of input voltage
85 - 265V! This is a large range in my book, only just got use to the possibility of any light bulb having a range of input voltage! Was not like that in my younger days! lol!

Would be very grateful if a kind person would enlighten me please! Oh dear!

 

[AndyPRK]

I'm surprised too.

A few months ago there was a power interupt of maybe 500ms at both my house and my parents. (transformer blown up at a neighbouring town IIRC).

TV's and video recorders worked fine throughout the interrupt.
However the LED's and CFL's went off. So I assumed it was a low voltage for a period of time and TV's were designed to work with lower voltages ok, but lights not.

 

[rsgaz]

Rather than have to manufacture different lamps for each country/region that uses different voltages and frequency, it's much simpler to make them work anywhere.

LEDs only want a few volts DC usually, so it's just that the power supply built into the lamp can take such a wide supply range. What the LED is given remains the same regardless.

 

[plugwash]

Contary to what rsgaz says the voltage can be quite high, each individual LED element is relatively low voltage (somewhere around 3-4 volts for a white LED) but there can be a lot of such elements in series.

Still the LEDs need a controlled current, ideally constant. Delivering that efficiently means a switchmode converter and once you are building a switchmode converter (especially one with power factor correction which the Eurocrats are pushing) it's only marginally more expensive to make it wide input.

 

[ericmark]

LED's need current regulation, there are three main ways to do this, a resistor, a capacitor, or a switch mode power supply, the latter changes the mark/space ratio to give an average current. The latter device will also work over a massive range mains 85 - 250 volt common, and with extra low voltage 10 - 30 volt DC is also common.

However there is a problem, with an AC supply you often get capacitive and inductive linking, and this energy builds up, so often the lights with the better switch mode drivers can flash from time to time when switched off, and also clearly correct any voltage or wave form clipping reduction so the lights will not work with a dimming switch.

 

[333rocky333]

video recorders worked fine

For a moment i was thinking Vhs or Betamax

 

[AndyPRK]

No. Hardisk !

 

[SUNRAY]

I'm surprised too.

A few months ago there was a power interupt of maybe 500ms at both my house and my parents. (transformer blown up at a neighbouring town IIRC).

TV's and video recorders worked fine throughout the interrupt.
However the LED's and CFL's went off. So I assumed it was a low voltage for a period of time and TV's were designed to work with lower voltages ok, but lights not.

We had something similar and it confused the hell out of me for a while
Kitchen - flou lights stopped but cooker still seemed to be ok and TV was on, fridge stopped.
Hall - LED's still on but not the CFL.
Lounge - wall lights CFL ok but 25w incandescent off, TV off but PVR still whirring.

I started looking for tripped breakers in the full knowledge it was a fools errand.

THEN
Cooker stopped.
Lounge - CFL went off but 25w came on very dim and TV came on with a dim picture.

At that point I started checking voltage - 80V L-N, 300V L-E.
Checked DNO's website and a fault in the area was known about.

Then everything went off so the camping cooker came in from the garage, as did a couple of leisure batteries and invertors. A neighbour knocked to inform us she had made a call and power outage of another 3 hours was predicted.
We were sitting there in a fully lit room eating our dinner with a TV going.

Oops We felt guilty and promised to help when our meal was finished.

 

[bernardgreen]

1982 ( or there abouts ) there was a power cut ( vandals shot out insulators on an over head 11kV line ) during which a neighbour called, Did we have a tin opener she could borrow, she only had an electric one and she couldn't feed her dog.

We had the open fire going and felt quite cosy with several neighbours keeping warm and being fed smokey toasted food.

Another power cut ( rural area with lots of over head lines ) was the day I had the company demonstration van at home ( with the bosses permisson ) to use it to collect building materials. It had a 3kVA generator.

 

[FrodoOne]

Found ordinary energy saving bulbs dimmed after a short time so purchased LED energy saving bulbs. Arrived today, checked them and found they could be used with a range of input voltage
85 - 265V! This is a large range in my book, only just got use to the possibility of any light bulb having a range of input voltage! Was not like that in my younger days! lol!

Would be very grateful if a kind person would enlighten me please! Oh dear!

In spite of all the other comments posted previously, the fact is that many devices which actually operate on an "Extra Low Voltage" only need this ELV to be derived from the higher "Low Voltage" Mains supply - be that from less than 100 V or a bit above 250 V.

Manufacturers are able to produce power supplies to convert from a small range of LV supplies to a particular ELV supply but it is not much more difficult or expensive to produce a similar device to convert from a wide range of LV supplies, and thus make the device concerned "Universal" - at leased as far as the commonly available "Mains" supply voltages (and frequencies) on planet Earth are concerned.

Be happy that you have such a group of such "Universal" devices.

 

[JohnW2]

LED's need current regulation, there are three main ways to do this, a resistor, a capacitor, or a switch mode power supply, the latter changes the mark/space ratio to give an average current. The latter device will also work over a massive range mains 85 - 250 volt common ....

I don't think one could use "mark/space ratio", per se, as the primary means of current limitation/control for an LED element. Yes, SMPSs often use that method for achieving an average ('effective') voltage output (and for dimming), but if there were not something additional to limit current, the LED element would probably blow up when the first pulse ('mark') hit it.

Kind Regards, John

 

[ericmark]

I don't think one could use "mark/space ratio", per se, as the primary means of current limitation/control for an LED element. Yes, SMPSs often use that method for achieving an average ('effective') voltage output (and for dimming), but if there were not something additional to limit current, the LED element would probably blow up when the first pulse ('mark') hit it.

Kind Regards, John

Agreed but keeping it simple

 

[JohnW2]

Agreed but keeping it simple

I'm not sure that 'wrong' and 'simple' are necessarily quote the same The problem was your talking in terms of 'current' regulation'.

I would have thought that the most 'simple' explanation, which has already been given, is along the lines that if one uses an 'electronic' means of converting the electricity supply into what is needed to feed the LED elements, it takes very little more effort/cost to produce one which can accept a very wide range of input voltages.

Kind Regards, John

 

[bernardgreen]

but if there were not something additional to limit current, the LED element would probably blow up when the first pulse ('mark') hit it

The main reason for early failure of LED elements. Most elements appear to survive the over current pulses but they are being damaged by migration of molecules through the semiconductor construction of the LED element. Eventually the device will fail.

 

[JohnW2]

The main reason for early failure of LED elements. Most elements appear to survive the over current pulses but they are being damaged by migration of molecules through the semiconductor construction of the LED element. Eventually the device will fail.

I'm not sure that they would even 'appear to survive' if there were no explicit (nor an appreciable implicit) means of current limitation - if, as eric seemed to be implying, a low mark/space ratio (of very high voltage pulses) were the only means of 'regulating' the (average) current through an LED element!

We are more used to the situation in which, say, an 'LED lamp' was designed to run directly off a 12V supply (hence containing some sort of current control/ regulation/ limitation), but was being supplied with '12V eff' which might be supplying, say, 30V pulses - but that is different.

Kind Regards, John