Short-circuit forces on reactor supports

The mechanical stress in the supporting members of any structure or apparatus under steady state is determined by the dimensions of the member and the magnitude of the resultant applied force. Under accelerated motion, however, an additional factor enters, namely, the reaction of the mass; and if the supporting members in this case are resilient, that is, spring-like, then this becomes still another factor which enters the problem of determining the mechanical stress produced by a given impressed force. The determination of the stress in the holding device (bolts, etc.) of reactors under short-circuit condition is just such a problem. If any motion whatever is permitted under this condition, the factors of mass and resilience are active. This paper gives a theoretical analysis of the problem, and shows that if any motion is permitted, thus allowing the factors of mass and resilience to become active, then the maximum stress may be significantly increased above that for no motion. Illustrative calculations show that this increase in practical cases may be of the order of 25 per cent. On the other hand, if motion of the reactors is prevented by sufficient initial bolt tension, or otherwise, then the maximum stress in the holding device obviously need be only as great as that corresponding to the maximum instantaneous peak of the electromagnetic force.