JPS644630B

PURPOSE:To obtain a phase-detecting tester to be used in construction sites, by conducting limit process of an input from a different measuring section at the identically low level, discriminating between different phase and same phase through a differential amplifier and indicating the result. CONSTITUTION:High voltage inputs from different measuring sections are converted to identically and extremely low level signals by limiter circuits 2 and 2', respectively, and they are compared with each other by a differential amplifier 3, and when they are of the same phase, the amplifier 3 makes no output, and it makes output only when they are of different phases. Even in case when there is a remarkable difference between these signals, the signals are converted to the same level, discriminated under the same condition and indicated on an indicator 5 as the same phase or different phase, and by using such a system as this, it is possible to obtain a highly reliable phase-detecting tester designed for being used in construction sites.