Abstract: Methods and apparatus for continuous ground fault self-test are disclosed. An example ground fault detection device includes a sense coil to detect current in a line conductor and a neutral conductor, the sense coil comprising a winding influenced by a current difference between the line conductor and the neutral conductor. The example ground fault detection device also includes a current bypass to facilitate a continuous current imbalance detected by the sense coil, and a ground fault detector circuit to detect at least one of the continuous current imbalance in the sense coil or a ground fault current imbalance.

Abstract: Methods and apparatus to minimize saturation in a ground fault detection device are disclosed. An example method includes connecting a capacitor simulator to a node of the ground fault detector device to prevent saturation, and monitoring power-line conductors for ground fault conditions with the ground fault detector device. An example apparatus to simulate a saturation capacitance in a ground fault device includes a sense coil induced by power-line conductors, and at least one of an amplifier or a current detector including an input connected to the sense coil and an output connected to a ground fault detector. The example apparatus also includes a saturation capacitor simulator connected to a node of at least one of the amplifier or the current detector to prevent saturation.

Abstract: Methods and apparatus to facilitate ground fault detection with a single coil and an oscillator are disclosed. An example ground fault detection device includes a sense coil including a secondary winding surrounding a line conductor and a neutral conductor, the line conductor and the neutral conductor forming a primary winding. The example ground fault detection device also includes a voltage oscillator connected in series with the secondary winding to drive an oscillation component, and at least one of a detector or an amplifier connected in series with the secondary winding to detect at least one of a neutral-to-ground fault or a line-to-ground fault.

Abstract: A ground fault detection device includes a sense coil including a primary winding and a secondary winding to detect current in a line conductor and a neutral conductor.

Abstract: A ground fault detection device includes a sense coil including a primary winding and a secondary winding to detect current in a line conductor and a neutral conductor. It also includes a capacitor in parallel with the secondary winding and a virtual inductor to form a resonance circuit having a signal proportional to the current and being indicative of a ground fault condition.

Abstract: Methods and apparatus to facilitate ground fault protection and self test with a single switch are disclosed. An example ground fault detection device includes a ground fault detector to receive a signal indicative of current in a line conductor and a neutral conductor, and a single switch to simulate a fault during a self test and to cause a relay to activate in response to at least one of a real fault or a failed self-test. An example method to self-test a ground fault detection device includes monitoring a self-test indicator for an indication to initiate the self-test, and when the indication to inititate the self-test is true, activating a switch to cause at least one fault diode to conduct for a predetermined self-test duration. The example method also includes monitoring at least one of a sense coil or the switch for a signal indicative of the self-test.

Abstract: Methods and apparatus to facilitate ground fault detection with a single coil are disclosed. An example ground fault detection device includes a sense coil to detect current in a line conductor and a neutral conductor, the sense coil including a primary winding and a secondary winding. The example ground fault detector also includes a capacitor in parallel with the secondary winding and an inductor to form a resonance circuit having a resonance frequency and having a signal proportional to the current, the signal indicative of a ground fault condition. An example method of detecting a ground fault includes driving a first capacitor with an inductor to generate a resonance signal component and monitoring an inductor signal to determine at least one of a neutral-to-ground fault, a line-to-ground fault, or a non-fault condition. The example method also includes generating a fault signal when at least one of the line-to-ground fault or the neutral-to-ground fault is detected.

Abstract: Methods and apparatus to minimize saturation in a ground fault detection device are disclosed. An example method includes connecting a capacitor simulator to a node of the ground fault detector device to prevent saturation, and monitoring power-line conductors for ground fault conditions with the ground fault detector device. An example apparatus to simulate a saturation capacitance in a ground fault device includes a sense coil induced by power-line conductors, and at least one of an amplifier or a current detector including an input connected to the sense coil and an output connected to a ground fault detector. The example apparatus also includes a saturation capacitor simulator connected to a node of at least one of the amplifier or the current detector to prevent saturation.

Abstract: Methods and apparatus for continuous ground fault self-test are disclosed. An example ground fault detection device includes a sense coil to detect current in a line conductor and a neutral conductor, the sense coil comprising a winding influenced by a current difference between the line conductor and the neutral conductor. The example ground fault detection device also includes a current bypass to facilitate a continuous current imbalance detected by the sense coil, and a ground fault detector circuit to detect at least one of the continuous current imbalance in the sense coil or a ground fault current imbalance.