The paper analyzed causes of override trip of underground power supply lines based on characteristics of multi levels and short lines of power supply lines of coal mine underground. designed a reverse locking type longitudinal protection device for override trip with 32-bit TMS320F2812 DSP as main processor. The test results showed that the protection device can solve the problem of o... https://www.roneverhart.com/Liftmaster-K1D8387-1CC-Expansion-Circuit-Board/