Weird.... fault

1 common dist board

10 circuits of led lighting..  separate rcbos  approx 40 led lamps total

Leds Suddenly started to dip for a split second every 50 seconds...  

Checked all connections tight...

Checked supply to dist board

No joy

Anyone any suggestions? 

Supply constant 246v

Any large loads? Either in your building or possibly near by? 

Sharpend said:

Any large loads? Either in your building or possibly near by? 

Click to expand...

Big building..... but nothing large or new comes to mind....  

Total building load approx 300A per phase....

Prob 100 rooms in building... so almost impossible to police loads

Have you put a clamp meter (tong tester) onto the incoming phases to see if a high current demand coincides with leds dipping. Any other testing done Hz?

The electricity board doesn’t happen to have a temp generator on the feed to that area due to say a cable fault does it?

Anybody doing any welding in the building?

Do the LEDs come back to a common controller like a DALI?

Could one faulty LED fitting in the circuit say briefly shorting, cause the rest to dip? Dunno.

Just thinking of various things of the top of my head.

Office? 

When you say every 50 seconds is this constant without a period where it settles.

Thanks for the replies

The building/site is a TV studios

The phase loading constantly changes with use.

You could say the whole site is probably 100 1ph rooms

60% with predictable loads, the remaining is unpredictable...

So phase balancing is erratic.

During the last 3-4 years we have replaced all the fluorescent office lighting with led panels but they all seem ok.  (Probably better drivers)

Currently the issue is just one film set.

No common controller.  Individual circuits

Tried each circuit from the board separately each still dips.  

So appears to be a supply issue....

Going to try today

Test supply cable

Installing better quality LEDs 

Check phase imbalance at site incoming supply (although this whole set is 1ph)

Another crude solution might be to restore the original tungsten lamps to the set

(They where replaced with LEDs 2 years ago)