Abstract: An energy monitoring arrangement that is operatively associated with a centrifuge instrument monitors the magnitude of applied accelerating energy that is used to accelerate a rotor and to interrupt the continued application of accelerating energy if the magnitude of the applied accelerating energy exceeds a predetermined reference energy value. Preferably, the net applied accelerated energy to the rotor is monitored and used in the comparison with the energy reference. The invention may also be used in a predictive manner to provide, early in the centrifugation run, an indication of the energy of a rotor at an operator-ordered set velocity.

Abstract: The duty cycle of the alternating current waveform applied to an electric motor is varied by varying the firing point of an SCR circuit. This firing point is varied by logic circuitry which responds to the largest (or smallest) output of several integrators each of which provides an increasing or decreasing control voltage in response to different error signals. The error signals are related to different control criteria such as motor speed, motor current, etc. Thus the error signal indicating the greatest deviation from a set point controls the firing point. Since the output level of the integrators is slow to vary, a high degree of noise immunity is attained.