Automatic range selector for volt-ammeter instrument

摘要: An automatic ranging clamp-on ammeter includes an openable normally closed magnetic core for encircling A.C. current carrying cable has a measuring winding and sensing winding. A meter, diode rectifier pair of variable first second resistors are connected in series across the relay solenoid is shunted by Zener with resistor sensitivity reducing shunt through open contacts betwen junction meter opposite terminal. audible signal generator may be resistor. When measured exceeds predetermined value closes inserts to reduce increase its range energizes generator. Alternatively from rectified fed being unidirectional switch whose gate way capacitor so that when voltage set range.