Document Type and Number:
Japanese Patent JPH0514231
Kind Code:
B2
Abstract:
PURPOSE:To enable the detection of the phase relationship with an inexpensive construction and free from the flow of a load current by picking up changes in a 3-phase AC power source using a optical coupling element to compare phase sequences depending on the output of the optical coupling element. CONSTITUTION:When a 3-phase AC voltage is generated from a 3-phase AC source 1, a light emitting element 11a lights during the half-wave with the first phase phi1 voltage giving a positive value to provide an emission output to a light receiving element 11b. Likewise, a light emitting element 13a lights during the half-wave with the third phase phi3 giving a positive value to provide an emission output to a light receiving element 13b. Consequently, when there is a positive phase relationship between the voltages phi1 and phi3, a signal of 'L' level is generated from the light receiving elements 11b and 13b. Therefore, a D type flip flop 15 is set given a positive relationship between the voltages phi1 and phi3 and a positive phase detection signal D of 'H' level is outputted from a setting output terminal. This enables the detection of the phase relationship with an inexpensive construction and free from the flow of a load current.
Inventors:
YAMAUCHI SATOMI
NAKAMURA TAKASHI
NAKAMURA TAKASHI
Application Number:
JP12660683A
Publication Date:
February 24, 1993
Filing Date:
July 12, 1983
Export Citation:
Assignee:
MITSUBISHI ELECTRIC CORP
International Classes:
G01R31/02; G01R29/18; H02H11/00
Next Patent: JPH0514232