Development of mine transient electromagnetic instrument based on constant large current emission and bipolar high speed acquisition and reception

Mine transient electromagnetic instrument is widely used to detect underground water bearing structure.In order to improve the signal strength of the secondary field and the anti-interference ability of the instrument, a transmitting system with H-bridge PWM bipolar modulation isolation drive, microprocessor preset current value, constant transmitting 50 A current and quick shutdown is developed; a receiving system with bipolar synchronous acquisition and 625 kHz high-speed superposition signal is developed; explosion-proof and intrinsically safe power supply to ensure mine safety.Through the detection of water abundance in coal mining face, the abnormal water bearing area is accurately divided, and the accuracy of the instrument is verified.