Patent ID: 6975490

Claim:
A phase state detecting apparatus, comprising: a phase detector for detecting first, second and third phases of a three phase current; an interrupt detector for detecting a falling edge of a pulse signal corresponded to the third phase of the detected first, second and third phases, recognizing an interrupt occurrence by the third phase when the failing edge is detected and generating a counting signal; a counter for counting a pulse signal corresponded to the first and second phases on the basis of the interrupt occurred-third phase according to the counting signal; an antiphase/open-phase detector for detecting a state as a normal connection state, an antiphase state on the basis of a pulse signal corresponded to the first or second phase counted by the counter and detecting an open-phase state on the basis of the interrupt counting times; and a display unit for displaying a message indicating the antiphase state or the open-phase state or the normal connection state on a screen according to a control signal of the antiphase/open-phase detector.