What does a "self-ballasted" LED mean ?

built in current limit???

It depends on the context.

possibly it has a resistor inbuilt for operation at some specified voltage.

In series with something that approximates a constant current source for some reasonable range of applied input voltages. Could be as simple as a crude ballast resistor or a semiconductor based device.

A bare LED has a rather rapid increase in current through it once it starts to glow with a slightly higher applied voltage leading vastly increased current and then total destruction if you go too high.

You can do some cute physics experiements plotting V-I curves for LEDs. eg.

Expect some LEDs to be destroyed in this practical.

Like any other PN junction: I(U) is exponential.

Best regards, Piotr

it means it has the require components inside to accommodate a direct connection to a commonly known source.

Even with that, you still need to ensure you get the correct one that matches the voltage you are attaching it to.

Jamie

Thanks. Your explanation seems to be the most likely one. We were looking at specifications for certification of AC wall socket compatible LED lamp in as Asian country.

That term is also used for dual transistors; means "resistor(s) added".