Transformer interface for preventing EMI-based current imbalances from falsely triggering ground fault interrupt
First Claim
1. An apparatus comprising:
- a first input port arranged to be coupled to a first voltage terminal of a source of power;
a second input port arranged to be coupled to a second voltage terminal of the source of power;
a third input port arranged to be coupled to ground potential;
a first output port arranged to be coupled by way of a ground fault interrupt circuit to a first terminal of an electrical load;
a second output port arranged to be coupled by way of the ground fault interrupt circuit to a second terminal of said electrical load;
a third output port arranged to be coupled by way of a filter circuit to said first and second terminals of said electrical load; and
an interface circuit, coupled to said first, second and third input ports and to said first, second and third output ports, and being operative to prevent the operation of said filter circuit from triggering the operation of said ground fault interrupt circuit.
2 Assignments
0 Petitions
Accused Products
Abstract
A transformer interface prevents a false ground fault interrupt in a power supply arrangement. The power supply arrangement has a line wire and a neutral wire connected by way of a ground fault interrupt circuit to an electrically powered device, to which a ground wire is also coupled. The interface has current imbalance sensor transformer windings coupled to the line and neutral wires. A ground wire current sensor transformer winding is coupled to the ground wire. A detector transformer winding produces a signal that triggers operation of the ground fault interrupt circuit, in response to the difference between currents produced by the current imbalance sensor transformer windings exceeding detected ground wire current by a prescribed value.
53 Citations
19 Claims
-
1. An apparatus comprising:
-
a first input port arranged to be coupled to a first voltage terminal of a source of power; a second input port arranged to be coupled to a second voltage terminal of the source of power; a third input port arranged to be coupled to ground potential; a first output port arranged to be coupled by way of a ground fault interrupt circuit to a first terminal of an electrical load; a second output port arranged to be coupled by way of the ground fault interrupt circuit to a second terminal of said electrical load; a third output port arranged to be coupled by way of a filter circuit to said first and second terminals of said electrical load; and an interface circuit, coupled to said first, second and third input ports and to said first, second and third output ports, and being operative to prevent the operation of said filter circuit from triggering the operation of said ground fault interrupt circuit. - View Dependent Claims (2, 3, 4, 5)
-
-
6. An apparatus for preventing a false ground fault interrupt in a power supply arrangement having a line wire and a neutral wire connected by way of a ground fault interrupt circuit to an electrically powered device, and including a ground wire to which said electrically powered device is coupled, said apparatus comprising:
-
a current imbalance sensor coupled to said line wire and said neutral wire and being operative to generate a first output representative of a current imbalance between said line wire and said neutral wire; a ground wire current sensor coupled to said ground wire and being operative to generate a second output representative of current through said ground wire; a detector, coupled to said current imbalance sensor and to said ground wire current sensor, and being operative to trigger operation of said ground fault interrupt circuit in response to said second output having a prescribed relationship with said first output. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
-
-
14. A method for preventing a false ground fault interrupt in a power supply arrangement having a line wire and a neutral wire connected by way of a ground fault interrupt circuit to an electrically powered device, and including a ground wire to which said electrically powered device is coupled, said method comprising the steps of:
-
(a) monitoring current flow through said line wire and said neutral wire and generating a first output representative of a current imbalance between said line wire and said neutral wire; (b) monitoring current flow through said ground wire and generating a second output representative of current through said ground wire; and (c) triggering operation of said ground fault interrupt circuit in response to said second output having a prescribed relationship with said first output. - View Dependent Claims (15, 16, 17, 18, 19)
-
Specification