Intelligent protection device with zero pressure drop

The invention provides an intelligent protection device with a zero pressure drop, relating to the electricity metering and protecting filed. The device comprises a first high-pressure operational amplifier and relay switching circuit, a second high-pressure operational amplifier and relay switching circuit, a third high-pressure operational amplifier and relay switching circuit, a power supply fault detection circuit, a first fault detection circuit, a second fault detection circuit, a third fault detection circuit and a PLC (Programmable Logic Controller), wherein the first fault detection circuit, the second fault detection circuit and the third fault detection circuit judge whether a first high-pressure operational amplifier, a second high-pressure operational amplifier and a third high-pressure operational amplifier fail or not by respectively detecting whether a communication pressure drop exists at both ends of a diode; the PLC controls relays in a first relay switching circuit, a second relay switchin