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Browse Prior Art Database

Current Measuring System

IP.com Disclosure Number: IPCOM000091057D
Original Publication Date: 1969-Sep-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Kahen, H: AUTHOR

Abstract

This system measures the flow of DC or AC in a conductor without disconnecting the conductor or making electrical contact with it. The system includes a magnetic core arranged in two pieces 12 and 14, which is clamped around conductor 10 for producing a magnetic field in response to current flow in such conductor. A magnetic-to-electric transducer 16, such as a Hall effect generator, is placed in a gap in the core. The output leads 18 and 20 of transducer 16 are connected to operational amplifier 30. This functions as an integrator due to a feedback path containing capacitor 26. The integrated output signal from amplifier 30 is applied to current driver 32, the output of which is connected to windings 34 on the core.

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Current Measuring System

This system measures the flow of DC or AC in a conductor without disconnecting the conductor or making electrical contact with it. The system includes a magnetic core arranged in two pieces 12 and 14, which is clamped around conductor 10 for producing a magnetic field in response to current flow in such conductor. A magnetic-to-electric transducer 16, such as a Hall effect generator, is placed in a gap in the core. The output leads 18 and 20 of transducer 16 are connected to operational amplifier 30. This functions as an integrator due to a feedback path containing capacitor 26. The integrated output signal from amplifier 30 is applied to current driver 32, the output of which is connected to windings 34 on the core. Driver 32 produces an output current in response to the amplifier output signal to oppose the field produced by the core. This, in turn, causes the output voltage from transducer 16 to become zero.

Amplifier 32 acts as a holding circuit. Its output voltage stays at a constant level and maintains the current in winding 34 at a constant value as long as there is no change in the current in conductor 10.

The value of the current 11 in conductor 10 is determined by the transformer equation N1I1=N2I2. N1 is the half-turn winding associated with transducer 16. N2 is the number of turns of winding 34 and I2 is the current in winding 34. These relationships are incorporated into meter 38 which, connected across resistor 36 in turn pl...