Induction watthour meter for power systems transmitting carrier communication signals
First Claim
1. An induction watthour meter for power systems transmitting carrier cOmmunication signals, comprising:
- an electromagnetic assembly including a voltage magnetic section having stator core made of a ferrite magnetic material and a current magnetic section having stator core made of a ferrite magnetic material;
a voltage metering coil on said stator core of said voltage magnetic section; and
a current metering coil on said stator core of said current magnetic section so as to define a metering circuit including said voltage and current metering coils connectable to power line conductors of a power system for measuring the consumption of electrical energy of a customer electric load with said power line conductors transmitting high frequency carrier signals of a communication system connected to said power system;
a terminating impedance network including said current metering coil and a capacitor element connected together to define a parallel resonant circuit tuned to said carrier signals such that said resonant circuit presents a predetermined value of impedance that is higher than the impedance of said customer electric load to said carrier signals when occurring in the same power line conductors supplying the electrical energy to the customer load.
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Accused Products
Abstract
Magnetic sections of an induction watthour meter include metering coils for connection as elements of a terminating impedance network for power line carrier communication signals. Stator cores of the magnetic sections are made of a ferrite magnetic material so that the metering coils can have predetermined high frequency resonant circuit characteristics. The terminating impedance networks are integral to the watthour metering circuit to provide high impedances for terminating the communication signal to reduce undesired effects on the signals due to low impedance customer electric loads and wide variations in the loads. An alternative embodiment includes a terminating impedance network connected in a watthour metering circuit in which a low impedance circuit protects against interfering high frequency signals originating at a customer'"'"''"'"'s premises.
28 Citations
7 Claims
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1. An induction watthour meter for power systems transmitting carrier cOmmunication signals, comprising:
- an electromagnetic assembly including a voltage magnetic section having stator core made of a ferrite magnetic material and a current magnetic section having stator core made of a ferrite magnetic material;
a voltage metering coil on said stator core of said voltage magnetic section; and
a current metering coil on said stator core of said current magnetic section so as to define a metering circuit including said voltage and current metering coils connectable to power line conductors of a power system for measuring the consumption of electrical energy of a customer electric load with said power line conductors transmitting high frequency carrier signals of a communication system connected to said power system;
a terminating impedance network including said current metering coil and a capacitor element connected together to define a parallel resonant circuit tuned to said carrier signals such that said resonant circuit presents a predetermined value of impedance that is higher than the impedance of said customer electric load to said carrier signals when occurring in the same power line conductors supplying the electrical energy to the customer load.
- an electromagnetic assembly including a voltage magnetic section having stator core made of a ferrite magnetic material and a current magnetic section having stator core made of a ferrite magnetic material;
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2. An induction watthour meter for power system transmitting carrier communication signals as claimed in claim 1 wherein said watthour meter includes a further terminating impedance network including the voltage metering coil and a further capacitor element connected together to define a parallel resonant circuit tuned to said carrier signals such that said resonant circuit presents a predetermined value of impedance that is higher than the impedance of voltage metering coil alone to the carrier signals.
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3. An induction watthour meter for power systems transmitting carrier communication signals as claimed in claim 1 wherein said watthour meter includes a still further terminating impedance network including a still further capacitor element connected in parallel with said voltage metering coil so as to have a predetermined value of impedance that is substantially lower than a maximum value of impedance of the customer electric load to the carrier signals so as to form a shunting path to an interfering high frequency signal generated at the customer load.
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4. An induction watthour meter for power systems transmitting carrier communication signals as claimed in claim 1 wherein the voltage metering coil is connected in the metering circuit for connection on the line side relative to the customer load side of the metering circuit connections;
- and includes a still further terminating impedance network including a still further capacitor element connected between said voltage metering coil and said current metering coil so as to be connected across the customer electric load and having a predetermined value of impedance that is substantially lower than a maximum value of impedance of the customer electric load to the carrier signals so as to provide a shunting path to an interfering high frequency signal generated at the customer load.
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5. An induction watthour meter for power systems transmitting carrier communication signals, comprising an electromagnetic assembly including a voltage magnetic section having stator core made of ferrite magnetic material and a current magnetic section having a stator core made of a ferrite magnetic material;
- a voltage metering coil on said stator of said voltage magnetic section;
first and second current metering coils on said stator core of said current magnetic section so as to define a metering circuit including said voltage metering coil and said first and second current metering coils connectable to power line conductors of a three-wire distribution network power system for measuring the consumption of electrical energy of a customer electric load with said power line conductors transmitting high frequency carrier signals of a communication system connected to said power system;
a first terminating impedance network including said first and second metering coils and further including first and second capacitor elements connected to define parallel resonant circuits tuned to said carrier signals such that either of said parallel resonant circuits present a predetermined value of impedance that is higher than the impedance of said customer electric load to said carrier signals when occurring in the power line conductors supplying the electrical energy to the customer load; and
a second terminating impedance network including third and forth capacitor elements connected in series and across said voltage metering coil with the junction of said third and fourth capacitor elements being connectable to a grounded neutral conductor of the three wire network.
- a voltage metering coil on said stator of said voltage magnetic section;
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6. An induction watthour meter for power systems transmitting carrier communication signals as claimed in claim 5 wherein said second terminating impedance network forms a parallel resonant circuit having said voltage metering coil tuned to said carrier signals.
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7. An induction watthour meter for power systems transmitting carrier communication signals as claimed in claim 5 wherein said third and fourth capacitors of said second terminating impedance network define a low impedance path having a predetermined value of impedance substantially lower than a maximum value of impedance of the customer electric load when the voltage metering coil is connected to the customer load side relative to the line side of the metering circuit connections;
- whereby either of said third and fourth capacitors form a shunting path to an interfering high frequency signal generated at the customer load.
Specification