Voltage detection apparatus and method for determining whether high voltage at input terminal exceeds preset value

A voltage detection apparatus for determining whether a high voltage at an input terminal exceeds a preset value, comprising a high-voltage arm and a low-voltage arm, wherein the low-voltage arm comprises a capacitor charging/discharging module, a signal indication module, a threshold selection module, a control module, and a signal transmission module;

• the high-voltage arm comprises a precision resistor R1;
• the capacitor charging/discharging module comprises a charging/discharging capacitor C1 and a diode VD2;
• the signal indication module comprises an optical-fiber emitting diode V1 and a voltage stabilizing diode VD;
• the threshold selection module comprises four parallel resistors R4, R5, R6, and R7 and corresponding switch contacts S1, S2, S3, and S4;
• the control module comprises a comparator D1 and a transistor switch VT1 controlled by the comparator D1;
• the signal transmission module comprises one optical-fiber emitting diode V2 and one optical-fiber emitting diode V3 that are connected in series, and once the transistor switch VT1 is turned on, a current pulse passes through the optical-fiber emitting diode V2 and the optical-fiber emitting diode V3, and an optical pulse appears in an optical-fiber cable as an output signal;
• a signal processing module is an upper computer or an optical signal acquisition system for receiving or processing optical signals emitted by the optical-fiber emitting diode V2 and the optical-fiber emitting diode V3;
• the high voltage at the input terminal flows into the low-voltage arm of a circuit via the high-voltage arm, and is connected via a first node;
• the charging/discharging capacitor C1 is connected to the diode VD2 via the first node and a second node;
• the optical-fiber emitting diode V1 and the voltage stabilizing diode VD of the signal indication module are connected in series, with a terminal of the optical fiber emitting diode V1 connected to the first node and another terminal of the optical-fiber emitting diode V1 connected to the second node;
• the threshold selection module is connected in parallel to two terminals of a resistor R2 and a resistor R3 via the second node and a third node;
• a terminal of the comparator D1 is connected to a base of the transistor switch VT1, and other two terminals of the comparator D1 are connected in parallel to the threshold selection module via the second node and the third node;
• the optical-fiber emitting diode V2 and the optical-fiber emitting diode V3 are connected in series, with a terminal of the optical-fiber emitting diode V2 connected to the first node and a terminal of the optical fiber emitting diode V3 connected to a collector of the transistor switch VT1.