Title:
TRANSFORMER FOR GROUNDED INSTRUMENT
Document Type and Number:
Japanese Patent JP3419168
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To miniaturize a transformer itself required for the continuous operation of a system by miniaturizing the capacitance of a resistor for the prevention of neutral point unstable phenomena to be inserted into a tertiary winding.
SOLUTION: A thermo-switch 5 and the operating contact 6b of a ground relay 6 are placed in series with a resistor 4 to be inserted into the tertiary winding of a transformer for grounded instrument. Usually, neutral point unstable phenomenon is prevented by the insertion of the resistor. If the resistor is about to reach the level of overheat due to vibration of a neutral point, the resistor is separated from the tertiary winding by the operation of the thermo-switch. In continuous operation at the level of alarm in which a ground fault of the system will not result, a high-level zero-phase voltage is continuously applied to the resistor. In a case where overheat prevention is likely to be delayed through thermo-switch operation, the resistor is separated from the tertiary winding by the operation of the ground relay.
Inventors:
Hiroya Kobayashi
Application Number:
JP25000595A
Publication Date:
June 23, 2003
Filing Date:
September 28, 1995
Export Citation:
Assignee:
KABUSHIKI KAISHA MEIDENSHA
International Classes:
H02H7/04; H02H3/20; H02H5/04; (IPC1-7): H02H7/04; H02H3/20; H02H5/04
Domestic Patent References:
| JP54110425A | ||||
| JP5594528A | ||||
| JP54153322U | ||||
| JP62182023U | ||||
| JP617332U |
Attorney, Agent or Firm:
Fujiya Shiga (1 person outside)
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