Safe Exposed Conductor Power Distribution System

• US 20130103220A1
• Filed: 12/07/2012
• Published: 04/25/2013
• Est. Priority Date: 10/27/2009
• Status: Active Grant

• Current Assignee: VoltServer, Inc.
• Original Assignee: VoltServer, Inc.
• Inventors: Eaves, Stephen S.
• Granted Patent: US 8,781,637 B2
• Time in Patent Office: Days
• US Class Current: 700/293
• CPC Class Codes: H02H 3/40 responsive to ratio of voltage and current
• CPC Class Codes: H02H 3/44 responsive to the rate of change of electrical quantities
• CPC Class Codes: H02H 7/261 involving signal transmission between at least two stations transmission of signals in general H02H1/0061
• CPC Class Codes: H02J 3/12 for adjusting voltage in ac networks by changing a characteristic of the network load

Abstract

A power distribution system (that can detect an unsafe fault condition where an individual or object has come in contact with the power conductors) regulates the transfer of energy from a source to a load. Periodically, the source controller opens an S1 disconnect switch, a and load controller opens an S2 disconnect switch. A capacitor represents the capacitance across the load terminals. If the capacitor discharges at a rate higher or lower than predetermined values after the S1 and S2 disconnect switches are opened, then a fault condition is registered, and the S1 and S2 switches will not be commanded to return to a closed position, thus isolating the fault from both the source and the load.

Claims

1. A power distribution system for regulating transfer of energy from a source on a source side and including source terminals to a load on a load side and including load terminals, the system comprising:

a) a source controller on the source side of the power distribution system responsive to a source sensor that provides feedback to the source controller that includes at least a signal indicative of the voltage across the source terminals;

b) a source disconnect device responsive to a control signal from the source controller for electrically connecting or disconnecting the source from the source terminals, wherein the source controller is configured to interrupt the supply of power by opening the source disconnect device when voltage is measured across the source terminals;

c) a load disconnect device for electrically decoupling the load from the load terminals; and

d) a logic device implemented in at least the source controller for determining whether the source disconnect device is to be opened to interrupt the electrical connection between the source and source terminals based on a predetermined set of conditions that includes at least whether the change in voltage across the source terminals in respect to time falls outside a predetermined range.

2. The power distribution system of claim 1, further comprising a load controller on the load side of the power distribution system responsive to a load sensor that provides feedback to the load controller that includes at least a signal indicative of the voltage across the load terminals.

3. The power distribution system of claim 2, further comprising a data communication link configured for the exchange of operating information between the source controller and the load controller, wherein the operating information includes at least a value indicative of the voltage across the load terminals that is acquired by the load controller.

4. The power distribution system of claim 3, wherein the data communication link comprises wireless communication circuits operating at carrier frequencies within the electromagnetic spectrum allowed by federal regulators.

5. The power distribution system of claim 3, wherein the data communication is accomplished by the modulator/demodulator in the source and load controllers that are operable to combine a communication signal with the voltage waveforms present on the source or load terminals, and to later separate the communication signal from the voltage waveforms present on the source or load terminals, such that the source and load controllers can communicate with each other using only the connections between the source and load terminals.

6. The power distribution system of claim 3, wherein the source and load controllers exchange a digital verification code that must match a predetermined value before energy transfer can be initiated.

7. The power distribution system of claim 2, wherein the source controller is configured to calculate the difference between the source terminal voltage acquired by the source controller and the load terminal voltage acquired by the load controller and to issue a command to open the source disconnect device if the difference does not fall between predetermined high and low values.

8. The power distribution system of claim 1, wherein the source disconnect device is responsive to a control signal from the source controller to vary the ratio of time that the source is connected to the source terminals in relationship to the time the source is disconnected from the source terminals so as to regulate the average energy transferred from the source to the load.

9. The power distribution system of claim 1, further comprising a current sensor that allows the source controller to acquire a signal indicative of the electrical current flowing from the source to the source terminals, and wherein the source controller is configured to to open the source disconnect device to disconnect the source from the source terminals if the electrical current exceeds a predetermined maximum value.

10. The power distribution system of claim 9, wherein the source controller is configured to periodically multiply the source terminal voltage measurements with the source current measurements resulting in a calculated instantaneous power value and to integrate consecutive power values to derive a total energy value.

11. The power distribution system of claim 10, wherein the source controller is also configured to apply a financial charge to the user for energy extracted from the source.

12. A method for implementing a power distribution system for the transfer of energy from a source to a load, where the power distribution system is configured to detect unsafe conditions that include electrically conducting foreign objects or individuals that have come in contact with exposed conductors in the power distribution system, the method comprising the steps of:

a) generating a responsive signal in a source controller to open a source disconnect device, resulting in the interruption of the electrical connection between the source and source terminals;

b) following the opening of the source disconnect device, acquiring a first measurement of the voltage across the source terminals using source terminal voltage sensors, and storing the first voltage measurement for access by the source controller;

c) after a predetermined time has expired, acquiring a second measurement of the voltage of the source terminals using the source terminal voltage sensor and storing the second voltage measurement for access by the source controller;

d) calculating the difference between the first stored voltage measurement and the second stored voltage measurement, wherein the difference represents the discharge rate of the capacitance across the source and load and terminals; and

e) generating signals from the source controller to close the source disconnect device if the difference between the first stored voltage measurement and the second stored voltage measurement falls within a predetermined high and low limits, wherein a discharge rate outside of the predetermined high and low limits indicates that there is a conducting foreign object or individual making electrical contact with the source or load terminals, or a failure in the power distribution system hardware.

13. The method of claim 12, wherein the source controller communicates with the load controller using at least one of an optical, conductive and wireless communication link.

14. The method of claim 13, wherein the source controller acquires a digital verification code from the load controller via the communication link and acts cause the source disconnect to remain in an open state if the digital verification code does not match a previously stored code resident in memory of the source controller.

15. The method of claim 12, wherein the source controller acts to vary the conductive time period of the source disconnect device in relation to the non-conductive time period of the source disconnect device such that the average energy transferred from the source to the load can be regulated according to an algorithm being executed by the source controller.

16. The method of claim 12, further comprising:

f) executing code in the source controller to acquire a measurement of the electrical current flowing through the source terminals using a current sensor;

g) storing the electrical current value in the source controller memory; and

h) opening the source disconnect device to disconnect the source from the source terminals if the electrical current exceeds a predetermined maximum value.

17. The method of claim 12, further comprising executing an algorithm in the source controller to calculate the difference between the source terminal voltage acquired by the source controller using the source terminal voltage sensor and the load terminal voltage acquired by the source controller from the load controller, and acting to open the source disconnect device if the difference between the source terminal voltage and the load terminal voltage does not fall between predetermined high and low limits.

18. The method of claim 12, further comprising, at the source controller:

f) acquiring a measurement of the electrical current flowing through the source terminals using a current sensor;

g) acquiring a measurement of the source terminal voltage using a voltage sensor;

h) periodically multiplying the source terminal voltage measurements by the source current measurements to derive an instantaneous power value; and

i) integrating consecutive calculated power values with respect to time to derive a total energy value.

19. The method of claim 18, further comprising applying a financial charge to a user of the energy for energy extracted by the user from the source.

20. The method of claim 12, wherein the source controller acquires a first measurement of the source terminal voltage using a voltage sensor while the source disconnect means is closed then acquires a second measurement of the source terminal voltage immediately after the source disconnect is opened and computes the difference between the first and second voltage measurement, and where the source controller takes action to open the source disconnect if the voltage difference falls outside of predetermined high or low limits.

21. The method of claim 20, wherein the source controller also acquires a measurement of the electrical current flowing through the source terminals using the current sensor while the source disconnect is closed, and divides the voltage difference by the current measurement to derive a value for the resistance of the conductors between the source terminals and the load terminals, and where the source controller takes action to open the source disconnect if the resistance value falls outside of predetermined high and low limits.

22. The method of claim 12, further comprising connecting a first source circuitry output conductor to a center tap point on a secondary coil of a first isolation transformer and connecting a second source circuitry output conductor to a center tap point on a secondary coil of a second isolation transformer, and where a first load circuitry input conductor is connected to a center tap point on a primary coil of a third isolation transformer and a second load circuitry input conductor is connected to a center tap point of a primary coil on a fourth isolation transformer, such that the configuration substantially cancels any flux produced in the four transformers due to current flowing from the source circuitry to the load circuitry, and where the remaining unused terminals of the four transformers can be used to transmit and receive data that is electrically isolated and independent of electrical current flowing from the source circuitry to the load circuitry.