Green burn-in

A research team at the Department of Electronic Engineering, City University of Hong Kong (CityU), has developed an energy-efficient burn-in system for power supplies that "reuses" electricity.

The system is expected to lower production costs for power supply manufacturers and save energy.
 
Electronic appliances like notebook computers and chargers for cell phones need a power supply to convert alternate current (AC) from the socket into direct current (DC). But before a power supply goes to the market, it has to go through the process of “burn-in”, a process which wastes a large amount of electricity.
 
'The conventional burn-in process connects resistors at the output of power suppliers in order to simulate a load condition, thus converting electrical energy passing through the resistors into heat energy. Not only does this process waste electricity, it also raises room temperature in manufacturing plants. This, in turn, entails installing costly ventilation systems to release the excessive heat,'  said Prof Henry Chung Shu-hung of CityU’s Department of Electronic Engineering.
 
'For instance, if you put 200 50W power supplies for notebook computers through a burn-in test for 10 hours, you will consume 100 kilowatts of electricity, which is equivalent to the amount of electricity a three-member household uses on average over three days, and the room temperature will be raised to 40 to 50 degrees Celsius,' he said.
 
To solve this problem, Prof Chung applied the idea of “recycling electricity”. With the support of his research students, he developed a “green” burn-in system which can recycle 70% of electricity used in traditional burn-in process.

'The idea is based on an energy recovery concept that uses high-efficiency DC/DC converters and
grid-connected inverters to feed the power output from the supplies back into the AC
grid. This results in reducing the energy drawn from the grid in the entire burn-in process,' Prof Chung told The Engineer Online.
 
'The system is more expensive than resistors, but, in the long run, costs are cut because less electricity is wasted, and less electricity is consumed through the ventilation system. Most significant of all, energy is saved,' he added.
 
The “green” burn-in system can be used for other electricity tests, such as battery tests in battery factories and power generators in power plants.