Load recorder

Abstract

This thesis describes the development of a computerized Load Recorder. The load recorder is used by the Cape Town City Council to assist in the tariff investigation of electricity consumers. This investigation assists the consumers in selecting the best cost effective electricity tariff. It also motivates the consumers to maintain a constant load which in turn assists the Council in supplying the required electricity. The load recorder replaces a manual and time consuming method used in conducting the tariff investigation. The development of the load recorder involved the design of hardware and software. It was designed in a compact enclosure to hook up to the electricity meters of the consumer for a period of 7 days. The software was designed in the 6805 assembly language to log data and record the electricity load every 15 or 30 minutes for this period. At the end of this period the data is downloaded into the HP85 personal computer. A basic program was designed for the HP85 to analyse and compute the downloaded data. A graphical representation and analysis is printed by the HP85 computer. The given graph of the results represents the electricity used for this period. The tariff rates are analysed and calculated to determine the best cost effective tariff. A CMOS micro computer intergrated circuit was chosen due to the determined specification of the load recorder. In order to make the development of the load recorder possible an aid (tool) had to be designed and built for the chosen microprocessor. This development aid, the emulator, is included as part of this thesis. The Motorola exorciser only supported a cross assembler for the chosen microprocessor family. The emulator was designed and built to enable testing and debugging on the Exorciser. The development on the emulator involved a detailed analysis of the Exorciser development system. The emulator was designed using hardware and software. The hardware emulator board was designed as a standard Motorola size card which plugs into the Exorciser. The software was designed for the 6809 exorciser and for the 6805 emulator. The emulator was soak tested and debugged during the development of the load recorder. The emulator opened further avenues for future microcomputer design projects especially where a confined area and compactness is an important factor. The design and development of the emulator and the load recorder was conducted in the Computer Section of the City Electrical Engineer's Department of Cape Town.