Title:
DC AND AC CURRENT SENSOR WITH DISCONTINUOUS SAMPLING
Document Type and Number:
WIPO Patent Application WO1999002997
Kind Code:
A3
Abstract:
Current is sensed by a circuit which provides a high frequency reversing voltage to a sensing winding on a current transformer, for driving the transformer into its linear region once per cycle of applied voltage. Current through the sensing winding is sampled while the transformer is in that linear region. After taking a current sample application of the reversing voltage, sensor power consumption is reduced by inhibiting the application of voltage to the sensing winding for one or more of the high frequency cycles, or the same control and sensing circuitry is used to cause application of reversing voltage to a sensing winding on a different transformer measuring current through a different conductor, such as in a polyphase arrangement or for monitoring ground fault current. Preferably, the current is sampled approximately at the instants of reversal of the voltage being applied to the sensing winding, and the sample having the lower absolute value is selected as a sample proportional to the line current.
Inventors:
GU WEN-JIAN
LEE NAI-CHI
LEE NAI-CHI
Application Number:
PCT/IB1998/001034
Publication Date:
April 08, 1999
Filing Date:
July 06, 1998
Export Citation:
Assignee:
KONINKL PHILIPS ELECTRONICS NV (NL)
PHILIPS NORDEN AB (SE)
PHILIPS NORDEN AB (SE)
International Classes:
G01R15/18; (IPC1-7): G01R15/18
Domestic Patent References:
| WO1996020408A2 | 1996-07-04 |
Foreign References:
| US5223789A | 1993-06-29 | |||
| US4314200A | 1982-02-02 |
Other References:
PATENT ABSTRACTS OF JAPAN, Vol. 13, No. 368, (P-919); & JP 01124772 A (HITACHI LTD) 17 May 1989.
PATENT ABSTRACTS OF JAPAN, Vol. 14, No. 61, (P-1001); & JP 01285866 A (FUJI ELECTRIC CO LTD) 16 November 1989.
PATENT ABSTRACTS OF JAPAN, Vol. 13, No. 426, (P-935); & JP 01158365 A (FUJI ELECTRIC CO LTD) 21 June 1989.
PATENT ABSTRACTS OF JAPAN, Vol. 14, No. 61, (P-1001); & JP 01285866 A (FUJI ELECTRIC CO LTD) 16 November 1989.
PATENT ABSTRACTS OF JAPAN, Vol. 13, No. 426, (P-935); & JP 01158365 A (FUJI ELECTRIC CO LTD) 21 June 1989.
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