Abridgment of quantitative mechanical analysis of power system transient disturbances

The fundamental mathematical methods for calculating system transients have been presented by other writers during the last few years. These mathematical calculations are of necessity quite involved and consequently can be applied only to very simple power systems. In the May 1926 issue of the Electric Journal, under the title “A Mechanical Analogy to the Problem of Transmission Stability” Mr. S. B. Griscom proposed the use of an accurate equivalent mechanical analogy to the electrical system provided perfect springs for representing line reactance could be obtained. The present paper covers the adaptation of the mechanical model principles to obtain reasonably accurate quantitative records of transients to be expected on the 220-kv. interconnection between the Philadelphia Electric Co., Pennsylvania Power & Light Co., and the Public Service Electric & Gas Co. These records are obtained by taking motion pictures of the equivalent mechanical system. Resistance or reactance short circuits on transmission lines are duplicated mechanically by applying forces of the proper magnitude and direction to the spring representing the line in trouble, and clearing this spring at each end by blowing fusible links from relays timed to represent the circuit breaker operations on the electrical system.