Neon power supply with midpoint ground detection and diagnostic functions
First Claim
1. A power supply for applying electrical power to a load while detecting a ground fault between the load and ground and/or connection of a load midpoint to ground, comprising:
- first and second power terminals for connection to the load for applying electrical power thereto,a ground terminal for connection to an earth ground connection,a power application circuit connected to the first and second power terminals and the ground terminal, wherein in a test mode the power application circuit applies electrical power to the first power terminal relative to the ground terminal while applying substantially no electrical power to the second power terminal relative to the ground terminal, and in an operative mode the power application circuit applies electrical power to both the first and second power terminals relative to the ground terminal,a ground fault detection circuit connected to the ground terminal for detecting electrical current flow between the ground terminal and the power application circuit, and for generating an electrical signal indicating the presence of a ground fault upon detection of current flow between the ground terminal and the power application circuit.
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Accused Products
Abstract
A power supply circuit detects ground fault paths, and miswiring of the load, using a test mode in which electrical power is applied to only one power output terminal of the power supply relative to the ground terminal, while substantially no electrical power is applied to the second power output terminal relative to the ground terminal. If application of power during the test mode causes substantial current flow through ground, then there is a ground fault path, or an incorrect connection between the midpoint of the load and ground. The power supply further includes unique features for signaling the presence and kind of fault it has detected; the power supply is capable of distinguishing between ground faults in at least two different locations, and when a fault is detected, the power supply signals the presence of the fault and its location, e.g., by timed blinking of the connected discharge light. These features are enhanced by a diagnostic analyzer for connection to the power supply. The diagnostic analyzer monitors power flow from the output terminals of the diagnostic analyzer to the input terminals of the power supply, and evaluates the power flow to identify power flow patterns indicative of a fault and the kind of fault. The power supply also reduces inrush current by disconnecting and reconnecting power to the transformer primary winding in opposite half-cycles of the alternating current electrical power.
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Citations
22 Claims
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1. A power supply for applying electrical power to a load while detecting a ground fault between the load and ground and/or connection of a load midpoint to ground, comprising:
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first and second power terminals for connection to the load for applying electrical power thereto, a ground terminal for connection to an earth ground connection, a power application circuit connected to the first and second power terminals and the ground terminal, wherein in a test mode the power application circuit applies electrical power to the first power terminal relative to the ground terminal while applying substantially no electrical power to the second power terminal relative to the ground terminal, and in an operative mode the power application circuit applies electrical power to both the first and second power terminals relative to the ground terminal, a ground fault detection circuit connected to the ground terminal for detecting electrical current flow between the ground terminal and the power application circuit, and for generating an electrical signal indicating the presence of a ground fault upon detection of current flow between the ground terminal and the power application circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A power circuit for applying electrical power to a load while detecting a ground fault between the load and ground and signaling the presence of the ground fault, comprising
first and second power terminals for connection to the load for applying electrical power thereto, a ground terminal for connection to an earth ground connection, a power application circuit connected to the first and second power terminals and the ground terminal, the power application circuit applying electrical power to the power terminals, and a ground fault detection circuit connected to the ground terminal for detecting electrical current flow between the ground terminal and the power application circuit while electrical power is being applied to the power terminals, and for generating an electrical signal indicating the presence of a ground fault upon detection of current flow between the ground terminal and the power application circuit, wherein the power application circuit is responsive to the electrical signal from the ground fault detection circuit to signal the fault and its location, the signaled location being one of at least two locations identifiable by the power application circuit.
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21. A method for applying electrical power to a load while detecting a ground fault between the load and ground and/or connection of a load midpoint to ground, comprising
connecting first and second power terminals to the load for applying electrical power thereto, connecting a ground terminal to an earth ground connection, applying electrical power to the first power terminal relative to the ground terminal while applying substantially no electrical power to the second power terminal relative to the ground terminal, while applying the electrical power, detecting electrical current flow between the ground terminal and the first power terminal, and signaling the presence of a ground fault upon detection of current flow between the ground terminal and the power application circuit.
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22. A method for applying electrical power to a load while detecting a ground fault between the load and ground and signaling the presence of the ground fault, comprising
connecting first and second power terminals to the load for applying electrical power thereto, connecting a ground terminal to an earth ground connection, applying electrical power to the power terminals, detecting electrical current flow between the ground terminal and the first or second power terminals while electrical power is being applied to the power terminals, and signaling a ground fault upon detection of current flow between the ground terminal and the power application circuit and identifying the location of the fault from among, at least two locations, by activity discernable to a user.
Specification