An investigation into appliance durability in the presence of power system disturbances
Document Type Article
The increased trend towards miniaturisation and greater efficiency in electronic equipment has also resulted in increased susceptibility to power system disturbances. Such equipment has become less tolerant to supply transients and variations and as a result there has been an increase in consumer product damage complaints. Greater consumer awareness has seen power quality become a major issue for both the domestic user and the utility companies. Arising from these issues an approach from the Electricity Supply Board of Ireland was made to engage into an investigation of the effects of power quality disturbances at the low-voltage domestic level.
On commencement of the research a study was made of power quality disturbances and the associated electromagnetic compatibility immunity (EMC) standards. Test limits and regimes from these standards have been used to carry out an investigation into the disturbance withstand capabilities of television, VCR and personal computer power supplies. Owing to the prevalence and widespread use of switch-mode power supplies in powering electronic apparatus, a study was made into the typical topologies and operation of the switch-mode power supply and a computer model was created using PSpice circuit simulation software. By simulation the model was used to assess how the power supplies perform when such disturbances were injected at their input.
A typical medium-voltage 20 kV section of the utility’s distribution network was also modelled in Matlab. The network was subjected to lightning surges and switching operations at various points on the network. The surge levels experienced were observed and the results were analysed to determine whether consumers at the low-voltage level would experience damage to their equipment.
Seminally, the results obtained are interesting in light of the current discussion on the introduction of the EN 50160 standard which proposes a significant increase in withstand limits which will have a major impact on equipment manufacturers, utility companies and ultimately, equipment end-users.