Leakage current detection device for appliances

Patent metadata

Field	Value
Publication number	US-9857448-B1
Application number	US-201615209563-A
Country	US
Kind code	B1
Filing date	Jul 13, 2016
Priority date	Jul 5, 2016
Publication date	Jan 2, 2018
Grant date	Jan 2, 2018

Abstract

A leakage current detection device includes a self-test unit for activating a simulated leakage current signal; a leakage current detection unit for detecting the simulated leakage current signal and the actual leakage current signal, where when at least one of them is present, the leakage current detection unit activates a trigger signal, and when both of them are absent, the leakage current detection unit deactivates the trigger signal; a self-test feedback turnoff unit for detecting the trigger signal, where when the trigger signal is detected, the self-test feedback turnoff unit deactivates the simulated leakage current signal before a predetermined time point; and a power line disconnect unit for detecting the trigger signal after the predetermined time point, and when the trigger signal is detected, it disconnects the power between the power source and the load.

First claim

What is claimed is:

1. A leakage current detection device connected between a power source end and a load end, comprising:
a self-test unit for periodically activating a simulated leakage current signal;
a leakage current detection unit for detecting the simulated leakage current signal and an actual leakage current signal, wherein when at least one of the simulated leakage current signal and the actual leakage current signal is present, the leakage current detection unit activates a trigger signal, and when both the simulated leakage current signal and the actual leakage current signal are absent, the leakage current detection unit deactivates the trigger signal;
a self-test feedback turnoff unit for detecting the trigger signal, wherein when the trigger signal is detected, the self-test feedback turnoff unit deactivates the simulated leakage current signal before a predetermined time point; and
a power line disconnect unit for detecting whether the trigger signal is present after the predetermined time point, and for disconnecting a connection between the power source end and the load end when the trigger signal is detected after the predetermined time point.

2. The leakage current detection device of claim 1 , wherein the self-test unit comprises:
a reference voltage generating sub-unit, for generating a reference voltage;
a periodic voltage generating sub-unit, for generating a periodically varying voltage, which is below the reference voltage during some parts of each period and above the reference voltage during other parts of each period;
a comparator, for comparing the reference voltage and the periodically varying voltage; and
a first transistor, for generating a simulated leakage current signal based on a comparison result output by the comparator.

3. The leakage current detection device of claim 2 , wherein the periodic voltage generating sub-unit includes a first resistor and a first capacitor connected in series.

4. The leakage current detection device of claim 3 , wherein the self-test feedback turnoff unit includes a second transistor, wherein a control electrode of the second transistor is connected to the leakage current detection unit, and wherein an anode to cathode path of the second transistor is connected in parallel to the first capacitor.

5. The leakage current detection device of claim 1 , wherein the self-test unit further comprises a self-test fault activation sub-unit for activating a self-test fault signal when a self-test fault occurs; and
wherein the power line disconnect unit disconnects the connection between the power source end and the load end when the self-test fault signal is activated.

6. The leakage current detection device of claim 1 , wherein the leakage current detection unit comprises:
a detector coil for detecting the simulated leakage current and the actual leakage current; and
a processor for activating or deactivating the trigger signal based on a detection result of the detection coil.

7. The leakage current detection device of claim 1 , wherein the power line disconnect unit comprises a delay sub-unit for delaying the detection of the trigger signal until after the predetermined time point.

8. The leakage current detection device of claim 7 , wherein the delay sub-unit is an RC circuit.

9. The leakage current detection device of claim 1 , wherein the power line disconnect unit comprises a trip solenoid or a relay.

10. The leakage current detection device of claim 9 , wherein the power line disconnect unit further comprises at least one transistor for activating or deactivating the trip solenoid or the relay.

11. An electrical connection device comprising the leakage current detection device of claim 1 .

Assignees

• Li Chengli

Inventors

• Li Chengli

Classifications

• G01R35/007 Primary

  Standards or reference devices, e.g. voltage or resistance standards, "golden references" · CPC title

• G01R31/025

  Physics · mapped topic

• G01R31/52

  Testing for short-circuits, leakage current or ground faults · CPC title