BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to electrical appliances, and in particular, it relates to an intelligent leakage current detection and interruption device for power cord.

Description of Related Art

Leakage current detection and interruption devices (LCDI) are a type of safety device to protect against electrical fire. Its main structure is a power cord with a power plug, and it functions to detect leakage current between the hot line or neutral line and the shield layer along the cord from the plug to the electrical load (e.g., air conditioner, dehumidifier, etc.). When a leakage current is detected, the device interrupts the electrical power to the load to prevent fire and ensure safety. Such devices can prevent arc fault fire due to damaged and improper insulation of the hot line, neutral line and ground line of the power cord, which may be caused by aging, wear and tear, pinching, animal chewing, etc.

Current LCDI devices (seeFIG. 1) has the following problems: when the leakage current detection line (shield line)24for the hot line L21or neutral line N22of the power line2is an open circuit and has lost its protection function, the power cord can still function to conduct power to the load. This presents a hidden threat of fire or other safety issue.

Therefore, there is a need for a leakage current detection and interruption device that can effectively detect leakage current.

SUMMARY

Accordingly, the present invention is directed to an intelligent leakage current detection and interruption device for a power cord, which includes: a switch module, configured to control an electrical connection of first and second power lines between their input and output ends; a leakage current detection module, including first and second leakage current detection lines coupled in series, configured to detect a leakage current on the first and second power lines, respectively; a detection monitoring module, coupled in series to the first and second leakage current detection lines and to the first and second power lines, configured to detect an open circuit condition in the first or second leakage current detection line; and a drive module, coupled to the switch module, the leakage current detection module and the detection monitoring module, configured to drive the switch module to cut off power to the output end in response to any detected leakage current or open circuit condition.

In some embodiments, the detection monitoring module includes at least one resistor and/or at least one diode.

In one embodiment, the detection monitoring module includes a first diode, a first resistor, a second diode and a second resistor, wherein a first end of the first diode is coupled to a first end of the first resistor, a second end of the first diode is coupled to one of the first and second power lines, a second end of the first resistor is coupled to the first leakage current detection line, a first end of the second diode is coupled to another one of the first and second power lines, a second end of the second diode is coupled to a first end of the second resistor, and a second end of the second resistor is coupled to the second leakage current detection line.

In some embodiments, the detection monitoring module includes a first resistor, a second resistor and a first diode.

In some embodiments, the first diode is shared by the drive module and the leakage current detection module.

In one embodiment, a first end of the first resistor is coupled via the first diode and the drive module to one of the first and second power lines, a second end of the first resistor is coupled to the first leakage current detection line, and the second resistor is coupled between another one of the first and second power lines and the second leakage current detection line.

In one embodiment, a first end of the first resistor is coupled via the first diode to one of the first and second power lines, a second end of the first resistor is coupled to the first leakage current detection line, and the second resistor is coupled via the drive module between another one of the first and second power lines and the second leakage current detection line.

In one embodiment, a first end of the first resistor is coupled via the first diode to one of the first and second power lines, a second end of the first resistor is coupled to the first leakage current detection line, and the second resistor is coupled between another one of the first and second power lines and the second leakage current detection line.

In one embodiment, the first resistor is coupled between one of the first and second power lines and the first leakage current detection line, a first end of the second resistor is coupled to another one of the first and second power lines, and a second end of the second resistor is coupled to the second leakage current detection line and also to a first end of the first diode.

In one embodiment, a first end of the first diode is coupled to a first end of the first resistor, a second end of the first diode is coupled to one of the first and second power lines, a second end of the first resistor is coupled to the first leakage current detection line, and the second resistor is coupled between another one of the first and second power lines and the second leakage current detection line.

In one embodiment, the first resistor is coupled between one of the first and second power lines and the first leakage current detection line, a first end of the first diode is coupled to another one of the first and second power lines, a second end of the first diode is coupled to a first end of the second resistor, and a second end of the second resistor is coupled to the second leakage current detection line.

In one embodiment, the first resistor is coupled between one of the first and second power lines and the first leakage current detection line, a first end of the second resistor is coupled to another one of the first and second power lines, a second end of the second resistor is coupled to the second leakage current detection line and also to a first end of the first diode, and a second end of the first diode is coupled to the drive module.

In one embodiment, the detection monitoring module includes a full-wave bridge rectifier, a first resistors and a second resistor, wherein the full-wave bridge rectifier is shared by the detection monitoring module and the drive module.

In one embodiment, a first end of the full-wave bridge rectifier is coupled to one of the first and second power lines, a second end of the full-wave bridge rectifier is coupled to a first end of the first resistor, a second end of the first resistor is coupled to the first leakage current detection line, a third end of the full-wave bridge rectifier is coupled to another one of the first and second power lines, a fourth end of the full-wave bridge rectifier is coupled to a first end of the second resistor, and a second end of the second resistor is coupled to the second leakage current detection line.

In some embodiments, the device further includes a test module, the test module including a test switch which is coupled to the switch module, the leakage current detection module and the detection monitoring module, and when the test switch is closed and no open circuit condition is present on the first and second leakage current detection lines, the drive module drives the switch module to disconnect power to the output end.

The leakage current detection and interruption device can detect whether the first and second leakage current detection lines are intact with no open circuit conditions, thereby enhancing the reliability of the device.

