Electronic summation metering scheme and microcomputer-based summator for maximum demand measurement in a multi-circuit supply arrangement

In Hong Kong, there are quite a number of commercial complexes, hotels, offices and Government organizations whose total electricity demands are as high as 6-10 MVA. In order to cater for such a large electricity consumption, several sources of supply circuits have to be arranged and the total demand to that particular electricity customer is then measured with a microcomputer-based summator. A general purpose microcomputer has been employed by The Hongkong Electric Company Ltd. (HEC) as a programmable metering summator to process the energy proportional pulses received from various active and reactive energy meters for the purpose of maximum demand calculation. This kind of self-assembled summator can handle 16 inputs and can retain important billing data such as maximum demand in the event of power failures. Other relevant information including the number of reset, cumulative and last maximum demand is also maintained. The author describes this system