Instability in D-C Aircraft Systems

A laboratory and theoretical study was made to determine the causes and methods of combating an unstable oscillatory voltage condition which has been encountered in aircraft d-c electric systems, using types P-1, P-2, and R-1 generators with carbon-pile voltage regulators. The generator characteristics were found to be such that oscillatory instability would not occur without the presence of a voltage regulator which was out of adjustment and which had inadequate damping. A method is given for determining the amount of damping required for stable operation in terms of the generator field time constant and certain regulator characteristics.