<p>A negative sequence occurring in a polyphase power system control including a continuous wave frequency transducer causes a second harmonic to be generated which for a 60 Hz system comprises a 120 Hz signal. In a preferred embodiment of the invention, the continuous wave frequency transducer includes an active 120 Hz notch filter having one stage which provides a component of the 120 Hz second harmonic. This signal is coupled to a second harmonic detector implemented by a semiconductor diode connected to the output of an operational amplifier. The detector diode is coupled to one input of a comparator circuit whose other input is coupled to a selectable DC reference signal. The comparator operates to generate a fault indicating signal indicative of a negative sequence when the output from the second harmonic detector exceeds the reference. The fault indicating signal is thereafter converted to a digital type signal which can be utilized by external utilization circuitry such as a system control circuit or a diagnostic subsystem.</p>
申请公布号
DE3742556(C2)
申请公布日期
1998.03.19
申请号
DE19873742556
申请日期
1987.12.16
申请人
GENERAL ELECTRIC CO., SCHENECTADY, N.Y., US
发明人
LARSEN, EINAR VAUGHN, BALLSTON LAKE, N.Y., US;SHIFLETT, RUSSEL GERALD, SALEM, VA., US