Leakage current detection device for appliances

Patent metadata

Field	Value
Publication number	US-2017222425-A1
Application number	US-201615080077-A
Country	US
Kind code	A1
Filing date	Mar 24, 2016
Priority date	Feb 2, 2016
Publication date	Aug 3, 2017
Grant date	—

Abstract

A leakage current detection device connected between a power source and a load, which includes a self-testing or leakage current detection selection trigger unit, for selecting a leakage current detection mode or a self-testing mode; a self-testing unit, for periodically generating a simulated leakage current signal in the self-testing mode; and a leakage current detection unit, for detecting a leakage current signal in the leakage current detection mode and detecting the simulated leakage current signal in the self-testing mode. The selection trigger unit further causes the power source to be disconnected from the load when a leakage current signal is detected, and sends a self-testing result to the self-testing unit depending on whether the leakage current detection unit detects the simulated leakage current signal. The self-testing unit displays an indication of the self-testing result.

First claim

What is claimed is:

1 . A leakage current detection device connected between a power source and a load, comprising:
a self-testing or leakage current detection selection trigger unit, for selecting a leakage current detection mode or a self-testing mode; a self-testing unit, for periodically generating a simulated leakage current signal in the self-testing mode; and a leakage current detection unit, for detecting a leakage current signal in the leakage current detection mode and detecting the simulated leakage current signal in the self-testing mode; wherein the selection trigger unit further causes the power source to be disconnected from the load when a leakage current signal is detected, and sends a self-testing result to the self-testing unit depending on whether the leakage current detection unit detects the simulated leakage current signal, and wherein the self-testing unit displays an indication of the self-testing result.

2 . The leakage current detection device of claim 1 , wherein the selection trigger unit includes a first silicon controlled rectifier (SCR), wherein the selection trigger unit selects the leakage current detection mode by controlling the first SCR to be conductive, and selects the self-testing mode by controlling the first SCR to be non-conductive.

3 . The leakage current detection device of claim 1 , wherein the selection trigger unit includes a fourth transistor and a fifth transistor, wherein the selection trigger unit selects the leakage current detection mode by controlling the fourth transistor to be non-conductive and controlling the fifth transistor to be conductive, and selects the self-testing mode by controlling the fourth transistor to be conductive and controlling the fifth transistor to be non-conductive.

4 . The leakage current detection device of claim 1 , wherein the selection trigger unit includes a fourth transistor and a photo-coupler, wherein the selection trigger unit selects the leakage current detection mode by controlling the fourth transistor to be non-conductive and controlling the photo-coupler to be conductive, and selects the self-testing mode by controlling the fourth transistor to be conductive and controlling the photo-coupler to be non-conductive.

5 . The leakage current detection device of claim 2 , wherein the selection trigger unit further includes a second SCR, wherein in the leakage current detection mode, the selection trigger unit disconnects the power source from the load by controlling the second SCR to be conductive, and in the self-testing mode, the selection trigger unit sends the self-testing result to the self-testing unit by controlling the conductive state of the second SCR.

6 . The leakage current detection device of claim 1 , wherein the selection trigger unit further includes a first fault indicator unit for indicating a leakage current fault condition.

7 . The leakage current detection device of claim 1 , wherein the self-testing unit includes:
a reference voltage generator sub-unit for generating a reference voltage signal; a periodic signal generator sub-unit for generating a period voltage signal, the period voltage signal being higher than the reference voltage signal during some part of a period and lower than the reference voltage signal during some other part of the period; a comparator, for comparing the reference voltage signal and the periodic voltage signal; and a first transistor, for generating the simulated leakage current signal based on a comparison result of the comparator.

8 . The leakage current detection device of claim 7 , wherein the self-testing unit further includes a second fault indicator unit for indicating a malfunction condition of the leakage current detection device.

9 . The leakage current detection device of claim 1 , wherein the leakage current detection unit includes:
detection coils for detecting the leakage current signal or the simulated leakage current signal; and a processor, for sending a detection result of the detection coils to the selection trigger unit.

10 . The leakage current detection device of claim 1 , further comprising:
a power supply unit, for supplying power to the selection trigger unit, the self-testing unit, and the leakage current detection unit; and a relay holding unit including a relay switch, the relay holding unit keeping the relay switch closed to connect the power source to the load after the leakage current detection device is energized.

11 . The leakage current detection device of claim 10 , wherein the relay holding unit includes a reset switch, a second transistor, and a third transistor, wherein when the reset switch is closed, the second transistor and the third transistor are conductive to keep the relay switch closed.

12 . The leakage current detection device of claim 10 , wherein the relay holding unit includes a relay capacitor, a second transistor, and a third transistor, wherein after the leakage current detection device is connected to the power source, the relay capacitor keeps the second transistor and the third transistor conductive to keep the relay switch closed.

13 . The leakage current detection device of claim 10 , wherein the relay holding unit includes an auxiliary switch linked to the relay switch.

14 . A power connection device including the leakage current detection device of claim 1 .

Assignees

• Li Chengli

Inventors

• Li Chengli
• Yue Guolan
• Zhang Wei

Classifications

• H02H3/05

  with means for increasing reliability, e.g. redundancy arrangements {(for logic circuits H03K19/003)} · CPC title

• H02H3/02 Primary

  Details · CPC title

• H02H3/335 Primary

  the main function being self testing of the device · CPC title