LED Light Bulbs

LED bulb includes a controller that steps down the input AC voltage and rectifies it to apply Low voltage DC to the lamp.

There are two things here which can affect the LED bulb when connected in 50Hz system:

1) The input transformer is likely to get overfluxed / overheated and thus fail prematurely.

2) With lower frequency, the voltage on secondary of input transformer is also lower, thus lowering the available at the lamp terminals. The lamp may still glow but the lumen output could be lower.

Not all LED lights are low voltage DC....I have several 120v LED lights....

https://www.ledmyplace.com/

https://www.ledsmagazine.com/ugc/iif/2014/10/10/new-compact-long-life-120v-plug-in-led-strip-light-from-solid-apollo-led.html

I have disassembled quite a few 120V LED lamps made for sale in the US, so presumably for 60Hz. I don't recall having seen even one which included a transformer in its circuitry.

Some time since that previous post, I did disasemble one 120VAC LED lamp that included a transformer in its driver circuitry. It was a tiny one, so almost certainly part of a (high frequency) switching power supply,. The power line frequency would be irrelevant to such a transformer, but larger capacitors might be required for 50Hz operation.

Should be no problem....

120V 60Hz bulb typically has screw type end cap to socket - some 50 Hz have bayonet caps. There are also different sizes of cap.

The LEDs only light with current in one direction, so have to be used "back to back" on AC or with a rectifier. Simplest current limiter for "AC" LED is capacitor but capacitor current is 20% higher at 60 Hz.

LEDs on 60Hz could be on for 8.3 ms then resting for 8.3 ms. It is 10 ms for 50Hz.

It is possible the current limiter is affected by frequency or different "on" time matters or amount of "flicker" is non-compliant [ only LED lamp I tested has 100% flicker].

i have fluorescent lamps marked 50/60 Hz and 50 Hz only - LEDs just 50Hz.

http://www.instructables.com/id/LED-TUBE-LGHT-AC/

I refitted a lot of 4 ft fluorescent bulbs in my house, I just removed the ballast and wired the 120v to the pins, they say any 2 pins will work, no worry about polarity...

They make the 4 ft tubes to work with or without ballast and/or starters, I just removed them all and wired direct with proper bulb types...

That will certainly work. But 20% more current at 60Hz - which may ruin the life of the poster's bulb.

If that capacitor or resistor fail it could be dangerous - LEDs are not rated as fuses and 1 watt resistors are not made for 10W surge

I doubt that the OP is building his own LED lights, and as you can see most are rated to accept 100-240 volts and 50/60 hz, in any case it should be mentioned on the spec sheet for the lights...

All but the lowest wattage LED bulbs use switching power supplies so there's a rectifier to create DC then it gets pushed through a very small high frequency transformer or inductor, no need for isolation so no need for a transformer. There may be an issue with ripple on the 180 volt DC supply on the front end but it's doubtful that would prevent it from working

Thanks for all the good responses.

I'm kind of convinced that it's going to work in 50 Hz power. The bulbs do contain a rectifier but I do not recall designing a rectifier for a specific frequency, it is designed for a specific input voltage only. But the power consumed (hence lumens) may be lower due to lower frequency. Does this make sense?

The reason that I'm asking this question is that I'm going on an assignment to Asia from US and we want to take all our table lamps with us. We really like our table lamps! I'm planning to carry spare LED bulbs as well to last for the time we are there!

Probably your best bet will be to take dimmable LED lamps (not all are). Those are operable on the variable duty cycle output of AC dimmers and more likely to respond gracefully to 50Hz, were there to be a problem.

...then replacement flexible cords (suitable for the higher voltages) and plugs (for the different sockets provided there) would be required also. Is a Qualified Electrician going to do the conversion?

I need to invest a bunch of money buying the voltage converters (240 VAC to 120 VAC), I'm not sure if 'dimmable' bulbs respond better to different frequency as it responds to varying resistance (current flow) and hence the power through the LEDs. Is that right?

Dimmable bulbs are more expensive; I still plan to take some but not all.

I don't completely follow your question, however, they have power supplies that accept and operate from non-sinusoidal AC at varying energy levels and are less likely to have a problem with only a different frequency. I suspect that on the dimmable lamps they supply a larger input filter capacitor to address the ripple issue that results from the output of a dimmer. That's the same solution to being operable on a lower frequency, use a larger filter capacitor.

NO! You should NOT need to buy voltage converters. Just buy bulbs that operate on 240V.

Some LED bulbs are rated for 100-240V, but not all. Read the labels before purchasing.

I have several candelabra brought from South America (presumably E27 Edison bases) that have US (E26) LED bulbs installed and working for many years on our 120V 60Hz.

I can't guarantee that the reverse is possible. Your best bet is to contact someone from the US, who has been in the specific country you are going to...

Buying 230V bulbs for lamps locally is good idea, but you need to change plug on table lamp or use adaptor to local type. Checking the lamp cable & switch are OK for 230V is essential and you could have worry of earthing if lamps have metal parts but are not double insulated

I would advise use of 2 pole 30 mA RCD (earth leakage cut-out breaking line & neutral) between local outlet [and on your 115VAC outlets] and you anyhow - there may not be such protection on house circuits where you go to work or assurance line & neutral are not swapped at socket (many plug types are reversible too). Local practice may not even have earth at socket.

You could also consider buying the bulbs when you get there. You might find that they're cheaper because you'll be closer to the country of origin.

A simple telephone call to the equipment manufacturer is all it takes...

The other thing you might get is a slight flickering of the bulb similar to a fluoro tube that's going out. Not strobe light, but enough to bother some people.

FWIW (and I'm going to offer this even if most of you already know it, since I can't tell), it might be worthwhile to understand how LED bulbs produce light, and thus how they differ from ANY other light producers we might find in our homes, pre-LED. This, by definition, includes any florescent, any incandescent, and in fact any bulb which produces notable amounts of heat DUE TO LIGHT PRODUCTION.

As I explain to my electronics, physics, and general science students when the subject comes up, almost every type of illuminator (It might be all, but I can't prove it, not knowing every kind of illuminator ever sold), some material is vaporized or otherwise broken down to make it give off some form of glowing particles. These are the light producers.

LEDs do no such thing. Rather, in an LED, energy is added to electrons flying in the valence shell of a "doped" material (usually silicon, though early LEDs used other base materials. Gallium Arsenide (GaAs) comes to mind.) causing the electrons so "pumped" to fly up one shell level. This leaves the "raised" electron with an artificially high energy state as well as leaving an "electron hole" in the vacated shell. The energy states thus reached are not maintainable without continuous pumping, and are not designed to be maintained. The electron, per design, decays, falls back into it's original "hole", and in so doing, gives off the residue of it's artificially pumped energy as light.

Two things worthy of note here:

1. NOTHING is destroyed in this process (contrast this with the description of the others forms of illuminators described earlier).

2. The description of a "hole" and falling back into it's original "hole", are literary tools to allow visualization of a series of events which have no discernible mass, thus no discernible velocity of action, and no ACTUAL, discernible, certain, position ANYWHERE. Heisenberg was NOT out of his gourd when he posited the "Uncertainty Principle" and it's corollaries.

I apologize for the pedantic approach, but several statements made above seem to be in error, given how LED's actually work. I'll leave it to others to re-read, and re-think, if necessary.

This sounds like low intensity discharge (like neon lights). LEDs also suffer from the same problem of creating (nearly) monochromatic light (one color, not white). To solve this the LEDs which we call white are actually ultraviolet with a fluorescent coating. This is not much different than fluorescent lights we have had for years using mercury vapor (ultraviolet) with a fluorescent coating. LEDs are more efficient not requiring a high voltage supply, low pressure tube, etc. I think a neon light would be about as efficient as a LED if we didn't mind the "red" light or some other gasses producing other single color light.

"I think a neon light would be about as efficient as a LED if we didn't mind the "red" light or some other gasses producing other single color light."

A standard NE2 running on 120VAC uses a 100kΩ resistor for current limiting/voltage dropping. The lamp itself uses 65V@0.6MmA =0.039W, and the lamp/resistor combination uses 120V@0.6mA = 0.072W. It requires a minimum of 65V, and there are very few voltage sources >65V and <120V, so most neon lamps operate on 120V in the US.

A similar indicating LED will use around 5 or 10 mA at around 1.2V or 0.006-0.012 watts. LEDs commonly have limiting resistors as well, but the losses depend on the operating voltage. This would imply an efficiency roughly 4 time that of an NE2.

There are, of course brighter Neon lamps, but they use correspondingly higher energies, and the same is true of LEDs.

I've never seen a Neon lamp of any kind that was so bright I couldn't look at it without pain. I've seen lots of LEDs that were too bright to look at directly. So any Neon lamp used for illumination would have to have a large area or many small lamps, even if we could accept the "red" light.

yes, you can. As LED Lights are made in order to work for 60 Hz frequency and 50 Hz os less than 60 Hz. So these lights work on 50 Hz power supply also. LED Lights which works best on 50 Hz power supply are LED Integrated Tubes Lights which is best suitable for large indoor spaces. LED Cooler Tubes Lights are best for freezers, coolers, refrigerators.