Abstract: A pseudokeyphasor signal control unit incorporated into apparatus for analyzing the vibratory behavior of a rotating machine in response to signals representing vibrations occuring in the machine, which apparatus includes: a controllable signal generator connected to receive an input signal representing the rate of rotation of the machine and to produce an output signal representing a rate of rotation bearing a selected relation to the rate of rotation represented by the input signal, the generator being responsive to digital signals which set the value of the selected relation; and a signal analyzing device connected to receive the signals representing vibrations and the output signal from the signal generator for processing the signals representing vibrations as a function of the machine rotation rate represented by the output signal from the signal generator.

Abstract: A method for accumulating stress damage induced by temperature differentials in a rotor of a high pressure steam turbine utilizes a representation of stress damage corresponding to a period of continuous temperature change. A counter variable associated with the representation of stress damage is incremented each time there is a significant change in direction of change in stress induced in the rotor. Accumulated stress damage is calculated by summing the products of each counter variable times a coefficient of stress damage corresponding to that counter variable. Accumulated stress damage is added to previously accumulated stress damage, calculated prior to resetting of the counter variables, to produce total accumulated stress damage. The total accumulated stress damage is printed on a permanent storage medium, such as paper, and it is compared with an alarm setpoint. If the alarm setpoint is exceeded, a message is sent to the operator and the operation of the steam turbine may also be adjusted.