Earth leakage detection circuit
First Claim
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1. An electric leakage detection circuit comprising:
- a zero-phase-sequence current transformer outputting a zero-phase current by detecting a ground-fault current;
a capacitor;
a circuit configured to operate an operation when said zero-phase current exceeds a predetermined positive side threshold value or when said zero-phase current falls below a predetermined negative side threshold value, and to control charge and discharge of said capacitor on the basis of said operation;
high potential points; and
a first resistor provided between said high potential points and said capacitor, whereinsaid circuit employs an open collector output,an output terminal of said circuit is connected to a contact provided between said first resistor and said capacitor, one end of said capacitor is connected to said contact, andsaid capacitor is charged and discharged on the basis of output of said circuit.
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Abstract
A zero-phase current is outputted by detecting a ground-fault current with a zero-phase-sequence current transformer. A circuit having an open collector output operates when the voltage of the zero-phase current exceeds a positive side threshold value or it falls below a negative side threshold value to discharge a capacitor. When the inter-plate voltage of the capacitor falls below a threshold value voltage, a controlling means detects electric leakage to transmit that to a control unit of an air conditioner.
4 Citations
3 Claims
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1. An electric leakage detection circuit comprising:
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a zero-phase-sequence current transformer outputting a zero-phase current by detecting a ground-fault current; a capacitor; a circuit configured to operate an operation when said zero-phase current exceeds a predetermined positive side threshold value or when said zero-phase current falls below a predetermined negative side threshold value, and to control charge and discharge of said capacitor on the basis of said operation; high potential points; and a first resistor provided between said high potential points and said capacitor, wherein said circuit employs an open collector output, an output terminal of said circuit is connected to a contact provided between said first resistor and said capacitor, one end of said capacitor is connected to said contact, and said capacitor is charged and discharged on the basis of output of said circuit. - View Dependent Claims (2, 3)
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Specification