EP0154450A1
Expired / Lapsed
EP
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Earth leakage protective circuit
Assignee: DELTA ELECTRICAL (HOLDINGS) Ltd
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Filing: 1985-02-21
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Granted: —
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Expires: 2005-02-21
Abstract
Abstract An earth leakage protective circuit has a contact breaker with its contacts (CB) in the live line (L) of the current supply. The coil (LI) of the circuit breaker has connected with it a semiconductor switch (CSR1) which is rendered conducting when earth leakage is detected by a circuit including a balance transformer (CT2) and an IC amplifier (IC1). To protect the load circuit additionally against loss of neutral, a second semiconductor switch (CSR2) is connected in series with the coil (L1). The second switch is controlled by a detector circuit (R9, D8, R12) which renders it conducting when the neutral supply line (N) becomes open-circuit, so that the circuit breaker contacts (CB) are opened.
Inventors
- 👤 Henry Charles Horton
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 21:04
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/26; H02H3/32; H02H3/33; H02H3/338
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
108 words
An earth leakage protective circuit comprising a contact breaker (CB, L1) intended to have its contacts (CB) connected in a supply line (L), a switching device (CSR1) connected with the coil (L1) of the contactor breaker to provide, when operated, a path for current through the coil (L1), and means (CT2, IC1) for detecting earth leakage and for controlling the switching device (CSR1) to cause the contacts (CB) to open when earth leakage occurs; characterised in that a second switching device (CSR2) is connected to provide, when operated, a second path for current through the contact breaker coil (L1) in the event of loss of the neutral supply.
Claim 2
Dependent Claim
108 words
An earth leakage protective circuit comprising a contact breaker (CB, L1) intended to have its contacts (CB) connected in a supply line (L), a switching device (CSR1) connected with the coil (L1) of the contactor breaker to provide, when operated, a path for current through the coil (L1), and means (CT2, IC1) for detecting earth leakage and for controlling the switching device (CSR1) to cause the contacts (CB) to open when earth leakage occurs; characterised in that a second switching device (CSR2) is connected to provide, when operated, a second path for current through the contact breaker coil (L1) in the event of loss of the neutral supply.
Claim 3
Dependent Claim
41 words
An earth leakage protective circuit according to claim 1, in which a detector circuit (R9, D8, R12) is arranged to detect loss of the neutral supply and is connected to operate the second switching device (CSR2) on detection of that loss.
Claim 4
Dependent Claim
67 words
An earth leakage protective circuit according to claim 2, in which the detector circuit (R9, D8, R12) is connected between an earth line (E) and a line (OV1) which is normally at the potential of the neutral supply 1ine-(N) but the potential of which rises when the neutral supply line uecomes open circuit, and responds to the change in potential to operate the second switching device (CSR2).
Claim 5
Dependent Claim
46 words
An earth leakage protective circuit according to claim 3, in which the detector circuit includes a non-linear impedance device (D8) which maintains a high impedance until the voltage between the earth line (E) and the line (OV1) normally at the neutral potential exceeds a given value.
Claim 6
Dependent Claim
48 words
An earth leakage protective circuit according to claim 3 or claim 4, in which the line (OV1) normally at neutral potential is connected through a resistance (R2, R14, R15, R4) to a further line (+V) which, in operation, is at the potential of the live supply line (L).
Claim 7
Dependent Claim
28 words
An earth leakage protective circuit according to any one of the preceding claims, in which the second switching device (CSR2) is a semiconductor in series with the coil.
Claim 8
Dependent Claim
43 words
An earth leakage protective circuit according to any one of claims 2 to 5, in which the second switching device is a thyristor (CSR2) and the detector circuit (R9, D8, R12) is arranged to control the current to the gate of the thyristor.
Claim 9
Dependent Claim
38 words
An earth leakage protective circuit according to any one of the preceding claims, in which the contact breaker (CB, L1) has two or more pairs of contacts, and is arranged so that the neutral connection is made first.
References Cited (Backward Citations)
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