BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to electrical appliances, and in particular, it relates to a leakage current (including ground fault) protection device with automatic or manual reset function when power resumes after an outage.

Description of Related Art

With the increasing awareness of electrical safety of electrical appliances, leakage current protection devices have become widely used. Due to differences in the connected appliance or environment, there are different requirements for the reset state of the leakage current protection devices after the electric power is connected or resumed after a power outage. For example, for a leakage current protection device used for a refrigerator or freezer, it is desired that when power is resumed after an outage, the leakage current protection device be automatically set to a connected state, so that the electrical appliance can work normally to reduce damage to the content stored in the refrigerator or freezer. On the other hand, for a leakage current protection device used for an electrical tool such as a cutting machine or other tools, it is desired that when power is resumed after an outage, the leakage current protection device be automatically set to a disconnected state, and require manual resetting to be connected, in order to ensure safety.

Therefore, there is a need for leakage current protection devices with desired reset functions after a power outage and that are easy to install and cost effective.

SUMMARY

Accordingly, the present invention is directed to a leakage current protection device with automatic or manual reset after power outage that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

To achieve the above objects, the present invention provides a leakage current protection device with automatic reset power outage and resumption, which includes: power lines, a switch module, a power supply module, a leakage current detection module, a drive control module, and a reset module. The power lines have an input end and an output end. The switch module is coupled on the power lines, and is configured to electrically connect or disconnect the input end and the output end. The power supply module is coupled to the input end, and is configured to generate a working power. The leakage current detection module is coupled to the power lines on the output side, and is configured to detect whether a leakage current is present on the power lines on the output side and to generate a leakage current signal when a leakage current is detected. The drive control module is coupled to the leakage current detection module and the switch module, and is configured to drive the switch module in response to the leakage current signal received from the leakage current detection module to electrically disconnect the input end and the output end. The reset module is coupled to the power supply module and the drive control module, and is configured to automatically control the drive control module to drive the switch module to electrically connect the input end and output end when power is resumed at the input end after a power outage.

In some embodiments, the power supply module is configured to supply a working power to the drive control module.

In some embodiments, the drive control module includes: a relay coil coupled to the reset module, configured to control the switch module; a drive control circuit coupled to the relay coil and the leakage current detection module, configured to control a current through the relay coil based on the received leakage current signal; and a manual reset switch coupled to the drive control circuit, configured to reset the drive control circuit after the leakage current signal is received.

In some embodiments, the drive control circuit includes a second transistor having a current path coupled in parallel with the reset switch, and having a control electrode coupled to the leakage current detection module to receive the leakage current signal. The second transistor is configured to become conductive in response to receiving the leakage current signal at its control electrode, and configured to become non-conductive in response to the reset switch being closed. The current path of the second transistor is coupled in parallel with a current path of the relay coil.

In some embodiments, the reset module includes: a first capacitor, a first resistor and a second resistor, and a first transistor. The first capacitor is coupled between the power supply module and ground. The first resistor and second resistor are coupled in series to form a voltage divider circuit. The voltage divider circuit is coupled in parallel to the first capacitor. The first transistor has a current path coupled in series with the relay coil and a control electrode coupled to the voltage divider circuit. The power supply module is configured to charge the first capacitor when power is resumed at the input end. The voltage divider circuit triggers the first transistor to become conductive based on a charged voltage of the first capacitor. When the first transistor is conductive, a current flows through the relay coil and the relay coil controls the switch module to electrically connect the input end and the output end.

In some embodiments, the device further includes a self-testing module coupled to the input end and the leakage current detection module, configured to periodically generate a self-test pulse signal that simulates the leakage current to test whether the leakage current detection module has a fault, and to generate a self-test fault signal when the leakage current detection module has a fault. The drive control circuit of the drive control module is further coupled to the self-testing module and configured to control the relay coil based on the self-test fault signal received from the self-testing module.

In some embodiments, the first transistor is a MOS (metal-oxide-semiconductor) transistor, a silicon controlled rectifier, or a bipolar junction transistor.

In another aspect, the present invention provides a leakage current protection device with manual reset after power outage and resumption, which includes: power lines, a switch module, a power supply module, a leakage current detection module, a drive control module, and a reset module. The power lines have an input end and an output end. The switch module is coupled on the power lines, and is configured to electrically connect or disconnect the input end and the output end. The power supply module coupled to the input end, and is configured to generate a working power. The leakage current detection module is coupled to the power lines on the output side, and is configured to detect whether a leakage current is present on the power lines on the output side and to generate a leakage current signal when a leakage current is detected. The drive control module is coupled to the leakage current detection module and the switch module, and is configured to drive the switch module in response to the leakage current signal received from the leakage current detection module or a trip signal to electrically disconnect the input end and the output end. The reset module is coupled to the input end and the drive control module, and is configured to automatically generate the trip signal when power is resumed at the input end after a power outage. In response to the trip signal, the drive control module drives the switch module to electrically disconnect the input end and output end.

In some embodiment, the drive control module includes: a relay coil coupled to the reset module, configured to control the switch module; a drive control circuit coupled to the relay coil and the leakage current detection module, configured to control the relay coil based on the received leakage current signal or the trip signal; and a manual reset switch coupled to the drive control circuit, configured to reset the drive control circuit after the leakage current signal or the trip signal is received.

In some embodiment, the drive control circuit includes: a second transistor having a current path coupled in parallel with the reset switch, and having a control electrode coupled to the leakage current detection module and the reset module to receive the leakage current signal and the trip signal; wherein the second transistor is configured to become conductive in response to receiving the leakage current signal or the trip signal at its control electrode, and configured to become non-conductive in response to the reset switch being closed, and wherein the current path of the second transistor is coupled in parallel with a current path of the relay coil.

In some embodiment, the reset module includes: a third resistor and a fourth resistor coupled to the input end; a fifth resistor and a second capacitor couple in parallel with each other and then coupled in series with the third resistor; a fourth transistor having a current path coupled in series with the fourth resistor and a control electrode coupled to a node between the third resistor and the fifth resistor; and a second diode coupled from a node between the fourth resistor and the fourth transistor to the drive control circuit, wherein the fourth resistor and the second diode generate the trip signal when power is resumed at the input end after a power outage.

In some embodiments, after the trip signal is generated, when the input end charges the second capacitor to a predetermined voltage, a voltage across the second capacitor triggers the fourth transistor to become conductive which stops the trip signal.

In some embodiments, when a voltage applied at the input end is lower than the predetermined voltage, the fourth transistor is non-conductive, and the fourth resistor and the second diode generate the trip signal.

In some embodiments, the device further includes another reset module, including: a first capacitor coupled between the power supply module and ground; a first resistor and a second resistor coupled in series to form a voltage divider circuit, wherein the voltage divider circuit is coupled in parallel to the first capacitor; and a first transistor having a current path coupled in series with the relay coil and a control electrode coupled to the voltage divider circuit; wherein the power supply module is configured to charge the first capacitor when power is resumed at the input end, wherein the voltage divider circuit triggers the first transistor to become conductive based on a charged voltage of the first capacitor, and wherein when the first transistor is conductive, a current flows through the relay coil, and the relay coil controls the switch module to electrically connect the input end and the output end.

In some embodiments, the device further includes a self-testing module coupled to the input end and the leakage current detection module, configured to periodically generate a self-test pulse signal that simulates the leakage current to test whether the leakage current detection module has a fault, and to generate a self-test fault signal when the leakage current detection module has a fault; wherein the drive control circuit of the drive control module is further coupled to the self-testing module and configured to control the relay coil based on the self-test fault signal received from the self-testing module.

In some embodiment, the second transistor is a MOS (metal-oxide-semiconductor) transistor, a silicon controlled rectifier, or a bipolar junction transistor.

In some embodiment, the fourth transistor is a MOS (metal-oxide-semiconductor) transistor, a silicon controlled rectifier, or a bipolar junction transistor.

Compared to conventional technology, embodiments of the present invention provides leakage current protection devices respectively having automatic and manual reset functions after power outage, which can meet the different requirements by different types of electrical appliances.

