Grid voltage mystery

Surprised you noticed, the LED PSU ought to just take a wider pulse each mains cycle, to get the same power?

I think that DNOs are now allowed to set a lower minimum voltage, precisely because of the prevalence of people feeding solar into the local grid, where you can't export if the grid isn't below your inverter's output voltage.

Before, the UK was 230V +10%/-6% now it's +/-10% but it shouldn't drop below 207V

Probably grid sagging due to loss of solar...

Eff all solar in SW Scotland today. Total generation less than 1kWh (from

No, this was a one off fault. Not seen anything like it before. Maybe a nuke went off-line?

Tim

We’re all LED bulbs now but they were all definitely dimmed to a greater or lesser degree. One wouldn’t light up at all. I was surprised by this personally.

Tim

Possibly loss of one phase of a 3 phase supply pushing resulting in star point rising to mean of the remaining phases.

Out of interest, why did you subject this /Grid/ voltage mystery? Surely it's the mains voltage which went down - the grid may well have been ok, and, for example, it was just one of the transformers in a substation which had problems. That seems to be the case as your DNO didn't appear to know of any issues.

Are you sure an engineer didn't have a look at the substation? We've got one on the path which runs by the side of our back garden, and have often been unaware that anything's going on until we've walked down that path and seen someone working inside the substation fencing.

For simplicity. My inverter lists “grid voltage” amongst its stats.

Our nearest one is literally across the road from my house. We would have seen & heard them. Maybe a more distant one had a fault though.

Tim

So what happens to "non dimmable" led bulbs when the mains voltage drops significantly ?.

I remember it dropped to 187V where I live. I phoned the EDF emergency number and the droids response was "so what".

Our mains voltage dropped to 96 V a few weeks ago when one of the HV phases to the substation failed. I was surprised that our LEDs - mainly Philips Hue - carried on as normal. Even out router and mesh network nodes were OK. My wife who works in a office upstairs in the bedroom didn't notice that anything was wrong until I went up to tell her: her lights were still on and her laptop still had internet connectivity.

Phillips Hue are dimmable and have a proper SMPS to run the blue tooth. The same with your router. If you check the "wall wart" for your router and the laptop PSU they are usually specified as 100-240v 50-60hz so 96v is likely to be within their actual capability.

Not sure about normal LEDS. I assume they use a capacitive dropper with a Zener diode to stabilise things. Probably stay at the same brightness until the Zener drops out, then go out.

Dave

So no, no dropper. Many use higher voltage LEDS matched to the mains voltage with a current sensing IC to tune the power consumption. They will drop out at some point...

... interesting video....

Dave

Dave

LED bulbs are a fast moving target technologically speaking.

There is no single 'one way to do it' circuit