Wattmeter
First Claim
1. A wattmeter for measuring the power passed by conductor means, comprising:
- current sensing means for measuring the instantaneous current flowing in said conductor means and for generating an induced current representative of the current flowing in the conductor means;
voltage sensing means for sampling the instantaneous voltage of said conductor means with respect to a voltage reference;
multiplier means responsive to the current sensing means and voltage sensing means for generating a product signal representative of the instantaneous power passed by the conductor means;
integrator means for integrating said product signal and generating a pulsed control signal with pulses having a frequency proportional to the average power passed by said conductor means, said integrator means including,means for integrating said product signal after each pulse of the pulsed control signal is generated and for generating a sum signal representative of the sum of the integrated product signal and a predefined power correction factor;
means for generating each pulse of said pulsed control signal for a predefined time interval when the magnitude of the sum signal is representative of a predefined value of power; and
means for defining a value of said power correction factor representative of measured power during said predefined time interval.
1 Assignment
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Accused Products
Abstract
An electronic wattmeter monitors the current and voltage of power lines and generates unitized voltage pulses at a frequency that is proportional to the average power carried by the lines. The wattmeter includes a current transducer that is inductively coupled to the monitored power lines. The transducer generates an induced current that is representative of the current that flows in the lines. The current transducer includes a magnetically permeable frame which has two magnetically permeable, spaced parallel leg members and a magnetically permeable cross-member that is detachably affixed between the leg members. The monitored power lines pass through an aperture defined by the leg members and cross-member of the frame and the frame additively applies the magnetic fields of the conductors to a coil that is inductively coupled to the frame. The coil generates an induced current corresponding to the current of the conductors. A multiplier samples the induced current at a rate defined by the line voltage and generates an output voltage signal that has an average intensity that is representative of the product of the line voltage and the current of the lines. An integrator successively integrates the output voltage signal of the multiplier to a particular magnitude and generates a unitized pulse for each integration up to the particular magnitude. An optical isolator generates an output signal that is modulated by the unitized pulses of the integrator and that is electrically isolated from the line voltage of the power lines.
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Citations
19 Claims
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1. A wattmeter for measuring the power passed by conductor means, comprising:
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current sensing means for measuring the instantaneous current flowing in said conductor means and for generating an induced current representative of the current flowing in the conductor means; voltage sensing means for sampling the instantaneous voltage of said conductor means with respect to a voltage reference; multiplier means responsive to the current sensing means and voltage sensing means for generating a product signal representative of the instantaneous power passed by the conductor means; integrator means for integrating said product signal and generating a pulsed control signal with pulses having a frequency proportional to the average power passed by said conductor means, said integrator means including, means for integrating said product signal after each pulse of the pulsed control signal is generated and for generating a sum signal representative of the sum of the integrated product signal and a predefined power correction factor; means for generating each pulse of said pulsed control signal for a predefined time interval when the magnitude of the sum signal is representative of a predefined value of power; and means for defining a value of said power correction factor representative of measured power during said predefined time interval. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In a polyphase power distribution system of a type wherein a plurality of conductor means distribute polyphase current at a voltage referenced across the conductor means, a plurality of improved wattmeters for measuring the power passed by said conductor means, each of said wattmeters comprising:
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a housing; a current sensing means for generating an induced current representative of the current passing through said conductor means, said current sensing means including, a coil for generating said induced current in response to a magnetic field of said conductor means, and a magnetically permeable frame for applying the magnetic field of the conductor means to the coil, the frame having an aperture and means for detaching at least a portion of the frame to allow the conductor means to be positioned to extend through the aperture; means for clamping said conductor means to said housing; multiplier means responsive to said current sensing means and the level of said voltage for generating a product signal representative of the instantaneous power passed by the conductor means; integrator means responsive to said product signal for generating a pulsed control signal representative of the average power passed by said conductor means, said integrator means including, means for integrating said product signal after each pulse of the pulsed control signal is generated and for generating a sum signal representative of the sum of the integrated product signal and a predefined power correction factor; means for generating each pulse of said pulsed control signal for a predefined time interval when the magnitude of the sum signal is representative of a predefined value of power; and means for defining a value of said power correction factor representative of measured power during said predefined time interval. - View Dependent Claims (17, 18, 19)
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Specification