Leakage current alarming/blocking apparatus using antiphase transformer

• US 6,057,996 A
• Filed: 11/19/1998
• Issued: 05/02/2000
• Est. Priority Date: 12/30/1997
• Status: Expired due to Fees

• Current Assignee: Dong Yang Hi-Tec Co., Ltd.
• Original Assignee: Dong Yang Hi-Tec Co., Ltd.
• Inventors: Kim, JungMoo
• Primary Examiner(s): Jackson, Stephen W.
• Application Number:
  US09/195,821
• Time in Patent Office: 530 Days
• Field of Search: 361/42, 361/45, 361/49, 361/58, 361/115
• US Class Current: 361/42
• CPC Class Codes: H02H 3/04 with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned watching of pilot wires H02H1/0084; protection of protective arrangements H02H7/008; indication of the state of electronic switches H03K17/18
• CPC Class Codes: H02H 3/33 using summation current transformers H02H3/347 takes precedence

Abstract

A leakage current alarming/blocking apparatus using an antiphase transformer for detecting the leakage of current from an electric appliance. The apparatus includes an antiphase transformer having an AC from a secondary side of a transformer which are antiphased with respect to a ground potential, a virtual ground unit connected with an output terminal of the antiphase transformer for forming a virtual ground potential, an electric appliance conductive material formed on a surface of an electric appliance connected with the virtual potential of the virtual ground unit, a leakage current detector for repeatedly detecting whether the current is leaked from the electric appliance conductive material and outputting a signal indicating that the current is being leaked, an electric power controller for blocking the supply of the electric power when the signal indicating the leakage of the current is input, an alarming signal generator for outputting an alarming signal when the signal indicating the leakage of the current is input from the leakage current detector, and a DC supply unit for converting the AC into the DC and applying the DC to the leakage current detector, the electric power controller, and the alarming signal generator, respectively, thereby preventing an electric shock by detecting and blocking the leakage current and displaying the same on the visual and audible signal display units.

Claims

1. A leakage current alarming/blocking apparatus, comprising:

an antiphase transformer in which the phases of an alternating current from a secondary side of the antiphase transformer is antiphased with respect to a ground potential;

a virtual ground unit connected with an output terminal of the antiphase transformer for forming a virtual ground potential;

an electric appliance conductive material formed on a surface of an electric appliance connected with the virtual potential of the virtual ground unit;

a leakage current detector for repeatedly detecting leakage current from the electric appliance conductive material and outputting a signal indicating leakage current;

an electric power controller for blocking the supply of the electric power when the signal indicating the leakage of the current is input;

an alarming signal generator for generating an alarming signal when the signal indicating the leakage of the current is input from the leakage current detector; and

a direct current supply unit for converting the alternating current into the direct current and applying the direct current to the leakage current detector, the electric power controller, and the alarming signal generator, respectively.

2. The apparatus of claim 1, wherein said virtual ground unit comprises a first resistor and a second resistor which are connected in series, with a common connection terminal between the first resistor and the second resistor, the first resistor and second resistor connected in parallel with an output terminal of a secondary side of an antiphase transformer, the common connection terminal between the first resistor and the second resistor becoming a virtual ground potential having a ground potential.

3. The apparatus of claim 1, wherein said virtual ground unit comprises a first condenser and a second condenser which are connected in series, with a common connection terminal between the first condenser and the second condenser, the first condenser and the second condenser connected in parallel with an output terminal of a secondary side of an antiphase transformer, the common connection terminal between the first condenser and the second condenser becomes a virtual ground potential having a ground potential.

4. The apparatus of claim 1, wherein said leakage current detector comprises:

a resistor connected between the electric appliance conductive material and the virtual ground unit forming an electric potential when there is leakage current from the electric appliance conductive material; and

an optical switching means having a light emitting device connected in parallel with the resistor through a protection resistor and a light receiving unit connected with a positive potential from the direct current supply unit for outputting a voltage or a current proportional to the amount of light from the light emitting device when an electric potential difference occurs in the resistor.

5. The apparatus of claim 1, wherein said leakage current detector comprises:

a resistor connected between the electric appliance conductive material and the virtual ground unit forming an electric potential when there is leakage current from the electric appliance conductive material;

an optical switching means having a light emitting device connected in parallel with the resistor through a protection resistor and a light receiving unit connected with a positive potential from the direct current supply unit for outputting a voltage or a current proportional to the amount of light from the light emitting device when an electric potential difference occurs in the resistor; and

a comparing means for comparing a voltage or a current from the optical switching means with a previously set reference value and outputting a predetermined signal when the voltage or current from the optical switching means exceeds the reference value.

6. The apparatus of claim 1, wherein said leakage current detector comprises:

a resistor connected between the electric appliance conductive material and the virtual ground unit forming an electric potential when there is leakage current from the electric appliance conductive material; and

an optical switching means having a light emitting device connected in parallel with the resistor through a protection resistor and a light receiving unit connected with a positive potential from the direct current supply unit for outputting a voltage or a current proportional to the amount of light from the light emitting device when an electric potential difference occurs in the resistor; and

an amplifying means for amplifying the voltage or current from the optical switching means and outputting the same.

7. The apparatus of claim 1, wherein said leakage current detector comprises:

a resistor connected between the electric appliance conductive material and the virtual ground unit forming an electric potential when there is leakage current from the electric appliance conductive material; and

an optical switching means having a light emitting device connected in parallel with the resistor through a protection resistor and a light receiving unit connected with a positive potential from the direct current supply unit for outputting a voltage or a current proportional to the amount of light from the light emitting device when an electric potential difference occurs in the resistor;

an amplifying means for amplifying the voltage or current from the optical switching means and outputting the same; and

a comparing means for comparing a voltage or a current from the amplifying means with a previously set reference value and outputting a predetermined signal when the voltage or current from the optical switching means exceeds the reference value.

8. The apparatus of claim 1, wherein said electric power controller comprises:

a relay connected with the electric power input terminal of the electric appliance and operated in accordance with a control signal for blocking the supply to the electric appliance; and

a switching means operated in accordance with a signal from the leakage current detector for controlling the operation of the relay.

9. The apparatus of claim 1, wherein said alarming signal generator comprises:

a visual signal display unit operated in accordance with a signal from the leakage current detector and displaying the leakage of the current; and

an audible signal display unit operated in accordance with a signal from the leakage current detector and indicating the leakage of the current.

10. The apparatus of claim 1, wherein said direct current supply unit is formed of a rectifying circuit using a double insulation transformer.

11. The apparatus of claim 10, wherein said rectifying circuit comprises:

a double insulation transformer;

a bridge radio rectifying circuit connected with a secondary side of the double insulation transformer for rectifying the alternating current;

a zenor diode connected in parallel with a radio signal output terminal of the bridge radio rectifying circuit for limiting the voltage from the bridge radio rectifying circuit below a predetermined value; and

a smoothing condenser connected in parallel with the zenor diode for smoothing the voltage from the zenor diode.

12. A method of preventing an electric shock from leakage current from an appliance, comprising:

antiphasing an alternating current from a secondary side of an antiphasing transformer with respect to a ground potential;

forming a virtual ground by connecting a virtual ground;

unit in parallel with an output of the antiphasing transformer;

coupling the virtual ground with an electric appliance conductive material;

detecting leakage current from the electric appliance conductive material;

outputting a leakage current signal indicating that there is leakage current;

generating an alarming signal when the leakage current signal is detected;

blocking the supply of electric power when the leakage current signal is detected;

converting the alternating current into a direct current and blocking the supply of electric power.

13. The method of claim 12, further comprising forming an electric potential when there is leakage current from the electric appliance conductive material.

14. The method of claim 12, further comprising generating a light signal proportional to the electric potential in response to the leakage current signal;

and

converting the light signal to a direct current or voltage proportional to the amount of the generated light.

15. The method of claim 12, further comprising

comparing the direct current or voltage with a previously set reference value;

and

generating a predetermined signal when the direct current or voltage exceeds the reference value.

16. The method of claim 12, further comprising switching off the electric power to an appliance in accordance with the leakage current signal.

17. The method of claim 12, further comprising displaying a visual signal operated in accordance with the leakage current signal.

18. The method of claim 12, further comprising displaying an audible signal operated in accordance with the leakage current signal.