LED lights failing

[Simon35]

On a project where I have got 8 off 300W LED fittings on a radial circuit from a 400 to 230V transformer.

The fittings are 230V supply, and keep failing either straight away or after a short time, except the one nearest the transformer, which is fine.

The fittings also seem to hum, so maybe a harmonics thing from the transformer?

If I put a plug top on one and plug it into a wall socket, no failure or hum. If I then supply it via the transformer it will fail.

Looking at the failed lights there is some blackening around a varistor on the LED board.

Any thoughts and ideas on the reasons for failure would be welcome.

 

[bernardgreen]

Have you measure the 230 volt ?

Odd the one nearest is ( apparently ) OK

What switching arrangement is ther controling the lights.

 

[mattylad]

What is the make & model of the light?

 

[Simon35]

What is the make & model of the light?

http://redarrowtrading.com/300w-smd-ac-floodlight-photocell-6000k-black.html

 

[Simon35]

Have you measure the 230 volt ?

Odd the one nearest is ( apparently ) OK

What switching arrangement is ther controling the lights.

Yep. Measured 230V at each light. Lights are controlled by a contactor.

 

[Taylortwocities]

This ere transformer. What are the details on that? A link would be good.

 

[bernardgreen]

quote="The description"]The LED AC Driverless Floodlights with Photocell [/quote] and ( from the spec sheet ) a voltage range of 180-240 volts.

If there is no driver then what regulates the current through the 336 LEDs ? ( 24 rows of 14 if the image is genuine )

If the current control is by resistors in series with groups of LEDs then voltage spikes from the transformer could easily damage the LED element. Switch other loads on the 400 volt side is likely to create spikes on the 230 v secondary.

The brightness would vary with supply voltage.

Could the photo cell be the culprit by not turning the lamps on ?.

EDIT not 3336 which was a typical typo

 

[JohnW2]

If there is no driver then what regulates the current through the 3336 LEDs ? ( 24 rows of 14 if the image is genuine )

24 x 14 x 8 = ?

Kind Regards, John

 

[JohnW2]

... 8 off 300W LED fittings on a radial circuit from a 400 to 230V transformer.

Why is that, assuming the 400V is 3-phase, is there no neutral available?

Kind Regards, John

 

[flameport]

blackening around a varistor on the LED board.

Almost certainly caused by poor power quality.

so maybe a harmonics thing from the transformer?

In a way.

 

[JohnW2]

Almost certainly caused by poor power quality.

If the varistor is (effectively or literally) in series with the supply. might one not expect that there quite possibly would be some blackening around it in the event of any mode of failure which resulted in excessive current flowing for some period of time?

Kind Regards, John

 

[Simon35]

Why is that, assuming the 400V is 3-phase, is there no neutral available?


Kind Regards, John

This ere transformer. What are the details on that? A link would be good.

https://www.ete.co.uk/product/transformer-380v-480v-to-110v-or-220v-50va-wide-input-voltage/

The project is modifications to an existing piece of equipment whose existing supply is TP + E..

 

[Simon35]

Almost certainly caused by poor power quality.


In a way.

Could you expand on "in a way" at all, please?

 

[bernardgreen]

Care is needed when using transformers with multiple taps on the windings to supply equipment that does not have good ( if any ) filtering on its mains supply.

If the end taps are not used then the end portion of the winding is an un-terminated ( unloaded ) auto-tranformer coil. Together with the inter winding capacitance this coil can resonant when the supply has a sudden ( non sinusoidal ) voltage change and by resonating it increases the duration of the transient effect

 

[flameport]

If there is no driver then what regulates the current through the 336 LEDs ?

Usually one or more custom ICs on the same substrate as the LEDs themselves.
Example: https://www.aliexpress.com/item/20W...lood-light-landscape-Ceiling/32295217646.html

'driverless' meaning there is no separate power supply or driver, 230V AC is connected directly to the PCB which contains both the LEDs and control devices.
The advantages being lower manufacturing costs, and the ICs have thermal sensing built in so can reduce the current in the event of the LEDs overheating.