AUTOMATIC POSITIVE-PHASING DEVICE FOR THREE-PHASE ANTIPHASE CONNECTION

摘要

PURPOSE:To eliminate need for the replacing labor of power supply wiring or inspection by discriminating the positive/negative of the phase order of power supplied from three phase power sources and applying the three-phase power sources by its phase order or a replaced phase order in accordance with the discriminated result. CONSTITUTION:When the phase order of the three phase power sources R, S, T is a positive phase, a compressor motor MC is driven directly by the phase order of the three phase power sources R, S, T. When the phase order of the three phase power sources R, S, T is the antiphase, a reverse rotation preventing relay RCR is not driven, its (a) contact Xa and (b) contact Xb are respectively turned on and off, a start relay M2 and a holding relay M4 are driven, (a) contacts M21 to M23, M44 are turned on and the (b) contacts M41 to M43 are turned off. Thus, the three-phase connection of the R, S, T is switched to the positive phase connection to drive the motor MC, the relays M2, M4 are self-held and current supply to the relay RCR is interrupted to prevent a resistor R in the relay RCR from being overheated. Consequently, the replacing labor of an external connection can be omitted.