Mcgraw-Edison Company

Cooper Industries, Inc.

Naresh K Nohria

Clyde Gilker

James R Hurley

Thomas G Dolnik

James A Jindrick

Michael Peter Dunk

Norbert J Reis

James A Baranowski

Thomas J Bray

The electric parameter metering machine comprises electric parameter pickup circuitry for sensing the instantaneous analog amplitude value of a electric parameter waveform in at least one phase in an electric power distribution system at selected time intervals during each full cycle, an A/D converter for converting the analog amplitude values to digital signals and signal processing circuitry including a memory for storing the digital signals. The signal processing circuitry includes a microprocessor operable to apply a conventional waveform analysis technique to the digital signal information collected with respect to a selected number of cycles of the electric parameter waveform to obtain an instantaneous RMS value of the electric parameter and operable to process a sequence of instantaneous RMS electric parameter values at discrete time intervals to obtain time averaged or demand electric parameter values. A visual display device is coupled to the signal processing circuitry and a pushbutton control panel is coupled to the signal processing circuitry for enabling an operator to operate pushbuttons to provide a digital readout of either instantaneous RMS, demand, or peak demand values on the visual display device.

Method and machine for metering electric parameters

A microprocessor based recloser control has a microcomputer for causing trip and close operations of a recloser in response to the conditions of the power distribution lines being protected and operator commands. The microcomputer may be overridden by a mechanical switch in the recloser control. If power to the recloser control is lost, the microprocessor will continue to function with power storage means for a limited duration. Towards the end of that duration, this microcomputer will power down the microprocessor in an orderly manner allowing automatic return to its functions when power is restored. After the microprocessor is no longer functioning, a secondary overcurrent trip circuit is relied upon to cause a trip operation of the recloser for extended durations of power outage. The secondary overcurrent trip circuit can be disabled by the microprocessor. The microcomputer includes means to normalize the input signals from the power distribution lines and multiple redundancy features to prevent undesired operations of the recloser. The recloser control functions in response to the mean square of the currents in the protected power distribution lines, and includes means for protecting its more sensitive components from input signals normally encountered.

Microprocessor based recloser control

A voltage regulating transformer utilizing a microprocessor and a versatile multipurpose set of hardware modules and software modules it is described. A standard tap changing mechanism is driven in response to an analog control signal to change the output voltage of the transformer in response to digitally sampled values of voltage and current which have been transformed from the time domain to the frequency domain through a software program using Fourier transform techniques. The output current is also transformed and digitally processed to determine the power factor and the direction of power flow through the transformer. By inserting the digital values of the line characteristics to the load, line drop compensation is provided for. The difference in voltage across the input and output transformers is transformed to a digital signal and internally processed to provide an indication of the position of the tap changing mechanism without relying upon mechanical devices. The various software and hardware modules are designed so as to be readily utilizable in other electrical distribution controls.

Microprocessor controlled voltage regulating transformer

Growing community of inventors

Milwaukee, WI, United States of America

Naresh K Nohria