Constant voltage in varied length cables

Claim 2

A circuit for maintaining constant voltage in electrical equipment from a power supply through cables of different lengths comprising: a transformer having a primary adapted for connection to a power supply, and having two identical secondaries, each having an end adapted for connection to a cable branch, and each secondary having several corresponding taps, a plurality of controlled switches, each switch being connected to a tap and to ground, an actuating control connected to the switches, the control having a voltage sensing means connected to a cable line and to the switches for selecting switches according to voltage at the sensing means.

Claim 3

A circuit according to claim 1 wherein the cable has first, second and third lines, wherein the ends of the secondaries are connected to the first and second lines, and wherein the sensing means is connected to the third cable line.

Claim 4

A circuit according to claim 1, wherein the switches are controlled semiconductors having power electrodes connected to ground.

Claim 5

A circuit according to claim 2, further comprising a constant current source connected to the third cable line.

Claim 6

A circuit according to claim 1, in which the voltage sensing means comprises a number of mutually blocking threshold switches connected one after the other, the number of these threshold switches being equal to the number of taps on each one of the secondaries, and each threshold switch being connected to one controlled switch at a tap on one secondary and to another controlled switch at a corresponding tap in the other secondary in such manner as to ground the corresponding taps when the switches are operated.

Claim 7

A circuit according to claim 5 wherein the control further comprises a like number of impedance transformers connected to the threshold switches, and wherein an output of each threshold switch is connected through a corresponding impedance transformer to control the electrodes of corresponding controlled switches.

Claim 8

A circuit for providing power to electrical equipment via cables of non-predetermined length while delivering the power at a relatively constant voltage, comprising: A. first and second power delivery lines, each having first and second ends, the first end of each of the first and second lines being connected to said equipment, B. a primary winding of a transformer connectable to an AC power source, C. first and second substantially identical secondary windings of the transformer, one end of each of the first and second windings being connected respectively to the second end of the first and second lines, D. a plurality of taps at equivalent positions on each of the secondary windings, E. switch means for connecting a selected tap from each of the secondary windings to a point of common potential, F. a third line in the cable connected to a point of common potential at said equipment and being connected to a test point at its other end, G. means for applying a current to the test point to generate a test voltage on the third line between the test point and the point of common potential at said equipment, and H. sensing means for measuring the test voltage and for operating the switch means to select the selected tap accordingly.

Claim 9

A circuit for providing power to electrical equipment via cables of non-predetermined length while delivering the power at a relatively constant voltage, comprising: A. first and second power delivery lines, each having first and second ends, the first end of each of the first and second lines being connected to said equipment, B. a primary winding of a transformer connectable to an AC power source, C. first and second substantially identical secondary windings of the transformer, one end of each of the first and second windings being connected respectively to the second end of the first and second lines, D. a plurality of taps at equivalent positions on each of the secondary windings, E. switch means for connecting a selected tap from each of the secondary windings to a point of common potential, F. a third line in the cable connected to a point of common potential at said equipment and being connected to a test point at its other end, G. means for applying a current to the test point to generate a test voltage on the third line between the test point and the point of common potential at said equipment, and H. sensing means for measuring the test voltage and for operating the switch means to select the selected tap accordingly.