Novel detector and difference clock circuits for generator frequency error monitors

A novel error-free detector circuit which overcomes the problem of error in difference detection is described. In the new 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 features of the difference detector are 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. Four such units were designed, manufactured, and installed at the hydropower stations in Sarawak, Malaysia