Simple microprocessor-based load angle measurement instrument

The design and implementation of a simple load angle measurement instrument built around a Z80 microprocessor is described. The task of the microprocessor is to measure the load angle of a synchronous generator which is equal to the phase angle between the internal excitation voltage and the generator output. The load angle is displayed on an on line screen. It is also converted to an analogue value and recorded by an online plotter for transient analysis a feature that makes such an instrument suitable for either digital or analogue controllers. The tests carried out showed that the instrument has a very fast response. It is accurate, reliable and inexpensive. The resolution in the load angle measurements can be increased by a simple procedure.