Current measuring apparatus and method
First Claim
1. Apparatus for determining the magnitude of a current to be measured flowing through a conductor, said apparatus comprising:
- a probe adapted to be coupled to the conductor;
a cabinet;
a Hall generator located in the probe, said Hall generator including first and second Hall inputs for receiving a bias current and first and second Hall outputs for producing a Hall voltage proportional to the current to be measured;
current control means located in the cabinet for controlling the bias current;
utilization means located in the cabinet for utilizing the Hall voltage;
adjustment means located in the probe for enabling the current control means to generate a predetermined value of bias current, so that the Hall voltage is calibrated; and
cable means for electrically interconnecting the adjustment means to the current control means and for conducting the bias current and Hall voltage between the cabinet and probe, whereby each probe can be individually adjusted by the adjustment means to be interchangeably connected to a variety of cabinets through the cable means.
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Accused Products
Abstract
The disclosure describes an improved apparatus for measuring the flow of current through a conductor by means of a Hall generator. The Hall generator is biased by a constant current source employing feedback. In order to increase the accuracy of the current measurement, operational amplifiers having inputs which float in relationship to the power supply operating the amplifiers are used to amplify the Hall generator output voltage and to drive a meter. The current measuring apparatus can be used to detect defects in a vehicular alternator by measuring the fluctuating components of the alternator output current. The magnetic field generated by the current to be measured is concentrated in the area of the Hall generator by means of a unique hollow, cylindrical, coiled strip of metal made from nickel, molybdenum and iron. The apparatus includes a regulator in which the voltage drop is so low that a 3.25 volt regulated supply can be maintained from a poorly-charged 6-volt battery.
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Citations
25 Claims
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1. Apparatus for determining the magnitude of a current to be measured flowing through a conductor, said apparatus comprising:
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a probe adapted to be coupled to the conductor; a cabinet; a Hall generator located in the probe, said Hall generator including first and second Hall inputs for receiving a bias current and first and second Hall outputs for producing a Hall voltage proportional to the current to be measured; current control means located in the cabinet for controlling the bias current; utilization means located in the cabinet for utilizing the Hall voltage; adjustment means located in the probe for enabling the current control means to generate a predetermined value of bias current, so that the Hall voltage is calibrated; and cable means for electrically interconnecting the adjustment means to the current control means and for conducting the bias current and Hall voltage between the cabinet and probe, whereby each probe can be individually adjusted by the adjustment means to be interchangeably connected to a variety of cabinets through the cable means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. In a system for determining the magnitude of a current to be measured flowing through a conductor by use of a Hall generator including first and second Hall inputs for receiving a bias current and including first and second Hall outputs for producing a Hall voltage proportional to the current to be measured, improved apparatus for reading out the Hall voltage comprising:
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power supply means for generating a DC voltage between a first power terminal and a second power terminal; current control means for enabling a controlled amount of bias current to be conducted from the first power terminal through the first and second Hall inputs to the second power terminal; first operational amplifier means including a first inverting input, a first non-inverting input, a first output, a first positive supply terminal, a first negative supply terminal, and a feedback loop; first connection means for operatively connecting the first power terminal to the first positive supply terminal; second connection means for operatively connecting the second power terminal to the first negative supply terminal; means for coupling an input voltage proportional to the Hall voltage across the first inverting input and the first non-inverting input; a meter responsive to current including a coil having an impedance; third connection means for connecting the meter in the feedback loop; and means for resistively coupling the power supply means to the first inverting input, first non-inverting input and first output, whereby the reading of the meter remains substantially constant irrespective of like changes in voltage on the first and second Hall outputs and irrespective of changes in the impedance of the meter. - View Dependent Claims (23, 24, 25)
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Specification