Abstract: Electronic circuitry monitors the electrical energy consumption of a system and displays the current cost of the energy usage. The projected monthly billing cost is calculated at the current rate of consumption, and an alarm signal is generated if the projected cost is higher than a budget amount. The current flow is sensed and digital pulses are fed to a microprocessor for counting and conversion to cost parameters. Clock pulses are also directed to the microprocessor for calculating the billing period and for displaying time parameters. A keyboard enables initializing and modifying the cost and time parameters in the microprocessor.

Abstract: An electronic monitoring circuit measures the amount of energy consumed by a system and displays the corresponding cost of the energy. An alarm circuit is triggered if the cost exceeds a predetermined amount over a given period of time. The monitoring circuit includes an electromagnetic coil which senses the magnitude of the input current and generates a d-c voltage having an amplitude corresponding to the current magnitude. The d-c voltage drives a voltage-controlled oscillator to generate an a-c signal having a frequency corresponding to the d-c voltage amplitude. The oscillator has been preset so that the generated a-c signal has a frequency representing a unit of cost of electrical power corresponding to the sensed current magnitude. A multivibrator generates a pulsed digital signal corresponding to the a-c signal frequency, each pulse indicating a unit of cost for the electrical power consumed.