Hook-on power factor, volt and ampere meter

Claim 2

In apParatus for the metering of electrical quantities in a three-phase circuit, a current transformer having a core magnetized in accordance with the current in a first phase of a three-phase circuit; a compensating winding inductively coupled to said core, means for supplying to said winding a current derived from the second and third phases of said three-phase circuit and having a 180* phase relation to the watt-component of said first phase current, a secondary winding inductively coupled to said core, and means for utilizing the resultant current induced in said secondary winding from said core for measuring power factor when the current derived produces a flux equal and opposite the flux produced by the watt component in the core.

Claim 3

Apparatus of claim 1, wherein said core is of the hook-on-type having a pair of hingedly connected core parts.

Claim 4

Apparatus defined in claim 1, wherein said last-mentioned means comprises a current-responsive meter having a pointer which cooperates with a fixed scale.

Claim 5

Apparatus according to claim 1, wherein said first-mentioned means includes adjustable means for varying the magnitude of the current supplied to the compensating winding.

Claim 6

Apparatus according to claim 1, wherein said first-mentioned means includes switching means operable to reverse the phase sense of the current supplied to the compensating winding.

Claim 7

Apparatus set forth in claim 5, wherein said first-mentioned means also includes adjustable means for varying the magnitude of the current supplied to the compensating winding.

Claim 8

Apparatus according to claim 1, wherein said first-mentioned means includes adjustable means for varying the magnitude of the current supplied to the compensating winding, and wherein said last-mentioned means comprises a current meter having a pointer which cooperates with a fixed scale.

Claim 9

Apparatus according to claim 7, wherein said first-mentioned means also includes switching means operable to reverse the phase sense of the current supplied to the compensating winding.

Claim 10

A multifunction apparatus for the metering of electrical quantities in a three-phase circuit, comprising a hook-on magnetic core for hooking onto one phase conductor and carrying a first winding and a second winding; a pair of leads for connecting respectively to the other two phase conductors, a current meter having two input terminals; and a multiposition switch operative in a first position to connect said pair of leads to respective opposite ends of said second winding and to connect the opposite ends of said first winding to respective ones of said meter input terminals, said first position being one wherein the core is coupled to a phase conductor, and operative in a second position to short circuit said second winding and to connect the opposite ends of said first winding to respective ones of said meter input terminals said second position being one wherein the core is coupled to a phase conductor.

Claim 11

A multifunction apparatus for the metering of electrical quantities in a three-phase circuit, comprising a hook-on magnetic core for hooking onto one phase conductor and carrying a first winding and a second winding; a pair of leads for connecting respectively to the other two phase conductors, a current meter having two input terminals; and a multiposition switch operative in a first position to connect said pair of leads to respective opposite ends of said second winding and to connect the opposite ends of said first winding to respective ones of said meter input terminals, said first position being one wherein the core is coupled to a phase conductor, and operative in a second position to short circuit said second winding and to connect the opposite ends of said first winding to respective ones of said meter input terminals said second position being one wherein the core is coupled to a phase conductor.

Claim 12

Apparatus according to claim 9, wherein said switch is operative in a third position to connect said pair of leads to respective opposite ends of said first winding and to connect the opposite ends of said second winding to respective ones of said meter input terminals, said third position being one wherein the core is not coupled to a phase conductor.

Claim 13

Apparatus defined in claim 10, including also a variable resistance connected in series with said second winding when said switch is in its third position.

Claim 14

Apparatus defined in claim 9, including also a variable resistance connected in series with said second winding when said switch is in its first position.

Claim 15

Apparatus defined in claim 12, including also a phase reversing switch connected in series with said variable resistance and said second winding when said switch is in its first position.

Claim 16

Apparatus defined in claim 9, including also a variable shunt resistance connected across said meter input terminals when said switch is in its second position.