I came home for work one evening after a wet and windy day. After unlocking the door I turned the lights on. I took a pasta bake from the fridge and put it in the oven. Checking the time on the clock on the oven, I saw it was time for the TV news.
20 minutes later my partner arrived home and I went to take the pasta bake out of the oven, but it was still cold. The fan in the oven was running, but there was no significant heat. Being an engineer I thought that the fan or thermostat must have failed. Being English I put the electric kettle on to make some tea and try to work out how I could heat the pasta. 10 minutes later the water had not boiled!
My next thought was to check the breakers in the fuse box. I went in to the utility room to check. Flicking the switch on the lights did not work. I found a torch and could see all the breakers were in the correct position.
After a little head scratching, I decided it was time for a multimeter. I checked the supply voltage and it was around 125 v not the expected 240 v. Thanks to my local electricity distribution operator SSEN , after a quick call power was restored. They said the storm earlier in the day had broken one of the three phases to a local transformer that fed my house.
My post incident investigation provided insight into the effects I had seen. The TV and LED bulb in the kitchen were universal input mains design and the bulb in the utility room was designed 230 v, but did not work at 125v.
This incident made me reflect on how modern electronic devices respond to electricity supply quality and following on, what impact devices have on electricity grids. Out of this, Sygensys was formed.
The experience of a partial failure of the electricity supply to a home shows that the concept of a brownout is changing . This is in part due to the impact of universal input electronics products.
Universal input means devices will operate with a power source input range 85 ~ 264 V AC and 45 ~ 65 Hz. Devices with this type of power supply can be used anywhere in the world without adjusting for supply characteristics. This is desirable for consumers and manufacturers alike.
The characteristics of LED lights at lower voltage can show unexpected characteristics for consumers. They do not respond in the same way as incandescent lights.
In the UK, and other countries with 230 V supply, a universal input LED light will continue to operate when the supply voltage is well outside a typical tolerance range of 230 V +/-10%.
Wikipedia described a brownout as “an intentional or unintentional drop in voltage in an electrical power supply system. The term brownout comes from the dimming of incandescent lighting when the voltage reduces. “
The image below shows three lights tested over a range of supply voltages. All were sold in UK for 230 V nominal operation.
The quartz halogen incandescent light on the right shows a classic brownout at 50 ~ 150 v. The two LED lights are both retailer own brand marked 220 – 240 V. They respond dramatically differently. The one of the left is universal input, working well over the range 75 – 250 V. By contrast the light in the middle works well only 200 – 250 V and provides no light output at 175 V.
LED lights spell the end of the classic brownout. The varying performance make it more difficult for consumers to understand what has happened to their supply. Distribution network operators also face a support challenges when contacted by customers for support.
Why does this matter?
Advice to consumers on how to identify power supply problems needs to be reviewed and updated. Much is still based around incandescent bulbs and old TVs with CRT display not LCD/OLED.
Choosing a universal input LED bulb can make lighting more reliable in emergencies after storms or on sites with poor power quality.
If you are interested in these issues please contact us.