| 摘要 |
A maximum current indicator to monitor the current flow in an electrical apparatus. A facsimile of load current from a current transformer is applied to a heater resistor. A sensor resistor having a high positive temperature coefficient is coupled to the heater such that the steady state temperature of the sensor is directly proportional to the power dissipated in the heater, making such temperature a function of the facsimile load current. The sensor resistor is part of a voltage divider network which includes a rheostat, the voltage across such divider being determined by a Zener diode. The divider output voltage at a junction thereof is determined by the sensor resistor and the rheostat. A pair of transistors are arranged in an emitter coupled binary circuit whose conduction states are determined by the voltage at the junction of the divider network. An isolation transformer and a silicon controlled rectifier form a switching circuit which is actuated by the binary circuit. A motor is controlled by the switch, the motor acting to set an indicator dial and also to drive the rheostat to a position for resetting of the binary circuit.
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