Electrical isolation device

An electrical isolation device comprising:

• (a) an enclosure having an interior;
• (b) first and second input terminals extending from the interior of the enclosure to the outside of the enclosure and connectable outside the enclosure;
• (c) a capacitor having first and second electrical terminals;
• (d) a first bus conductor connected between a first input terminal of the device and the first terminal of the capacitor and having a first straight flat section and a second straight flat section spaced from the first;
• (e) a second bus conductor connected to the second terminal of the capacitor and to the second input terminal and having a straight flat section spaced between the first and second straight flat sections of the first bus conductor;
• (f) two diode stacks each comprising plural diode layers, each diode layer having a diode junction wafer with an anode side and a cathode side which is capable of conducting electricity predominantly only in one direction from one side to the other, and at least one conducting metal separation disk in contact with a side of the diode junction wafer, wherein the diode layers are stacked together in each stack such that the diode stack predominantly conducts electricity in only one direction, wherein one diode stack is placed between the first straight flat section of the first bus conductor and the straight flat section of the second bus conductor such that each diode stack conducts electricity predominantly only from the first bus conductor to the second bus conductor and wherein the second diode stack is placed between the second straight flat section of the first bus conductor and the straight flat section of the second bus conductor such that the second diode stack conducts electricity predominantly only from the second bus conductor to the first bus conductor;
• and
• (g) a clamp connected to apply pressure to the first and second straight flat sections of the first bus bar, the straight flat section of the second bus bar, and the two diode stacks to press the layers of each stack into good electrical contact with an adjoining layer or sections of the bus conductors.

An electrical isolation device comprising:

• (a) two diode stacks each comprising at least one diode layer and at least one of the stacks having a plurality of layers in stacked relation, the number of diode layers in each stack being unequal, each diode layer including a diode junction wafer with an anode side and a cathode side and which is capable of conducting electricity predominantly only in one direction from one side to the other, the diode layers stacked such that each diode stack predominantly conducts electricity in only one direction;
• (b) input terminals connectable to electrical lines;
• and
• (c) electrical conductors which connect the diode stacks in parallel with each other across the input terminals such that when large fault currents are conducted through the device electricity is predominantly conducted in one direction through one diode stack and in an opposite direction through the other diode stack, and wherein the number of diode layers in each diode stack is chosen such that when an AC current sufficient to cause both diode stacks to conduct is applied to the input terminals there is a net DC voltage across the input terminals of between about -0.70 and -2.50 volts.

A method of providing cathodic protection by providing a net DC voltage to a metal structure, comprising the steps of:

• (a) providing an electrical isolation device comprising two diode stacks each comprising at least one diode including a diode junction with an anode side and a cathode side, and which is capable of conducting electricity predominantly only in one direction from one side to the other, such that each diode stack predominantly conducts electricity in only one direction, at least one of the diode stacks having a plurality of diode junctions, the number of diode junctions in each stack being unequal;
• input terminals connectable to electrical lines;
• electrical conductors which connect the diode stacks in parallel with each other across the input terminals such that when large fault currents are conducted through the device electricity is predominantly conducted in one direction through one diode stack and in an opposite direction through the other diode stack;
• and wherein the number of diode junctions in each diode stack is chosen such that when an AC current sufficient to cause both diode stacks to conduct is applied to the input terminals there is a net DC voltage across the input terminals of between about -0.70 and -2.50 volts;
• (b) electrically connecting one of the input terminals to the metal structure;
• (c) electrically connecting the other input terminal to ground;
• and
• (d) applying an AC current to the metal structure and across the input terminals sufficient to cause both diode stacks to conduct to provide a net DC voltage to the metal structure of between about -0.70 and -2.50 volts.

An electrical isolation device comprising:

• (a) a plurality of diode stacks each comprising at least one diode layer, each diode layer including a diode junction with an anode side and a cathode side and which is capable of conducting electricity predominantly only in one direction from one side to the other, the diode layers stacked such that each diode stack predominantly conducts electricity in only one direction;
• (b) a capacitor;
• (c) input terminals;
• (d) electrical conductors which connect the capacitor across the input terminals and connect the diode stacks in a bridge configuration with AC terminals of the bridge which are connected by the conductors across the input terminals in parallel with the capacitor, a diode stack forming each arm of the bridge and the bridge having DC terminals across which one of the diode stacks is connected, such that when large fault currents are conducted through the device electricity is conducted in both directions across the AC terminals of the bridge;
• and
• (e) a clamp connected to apply pressure simultaneously to all of the diode stacks and the electrical conductors to press the layers of all of the diode stacks into good electrical contact with adjoining layers and the electrical conductors.