Novel detector and difference clock circuits for generator frequency error monitors

All detectors are subject to error in difference detection. Where this detection error is integrated by a clock, it may run up to a few seconds, defeating the whole purpose of the clock. A description is presented of an error-free detector circuit which overcomes this problem. In this design, a detector circuit continuously compares the generator clock and the standard clock. Based on the comparison, it outputs up- or down-count pulses appropriately. The unique feature of the difference detector is its absolute zero error in error detection and low cost of manufacture. A difference clock which responds to the up- or down-count pulses supplied by the error detector and displays the error time is also described. This error time clock displays either positive or negative time, depending on the status of the integral error of the power station frequency