Tolerable Limits of Voltage Fluctuations Produced by Magnets Pulsed Directly from Alternating Current Power Lines

Switching magnets, for time sharing of beam lines, can be pulsed directly from the ac power line if it does not cause objectionable line voltage fluctuations (flicker). Switching circuits, which are less expensive and more reliable than conventional magnet power supplies are often all that are needed. Of particular interest for beam lines of the Zero Gradient Synchrotron (ZGS) was a test to determine the permissible attenuation of 1 cycle of the 60 Hz power line every 2 s. Other tests included multiple cycle attenuation at different repetition rates and square wave modulation of the ac power line. Thresholds of perception and the distribution of opinions on the flicker disturbance as functions of voltage attenuation were determined for viewing TV and reading by incandescent light. The results of these tests are reported and can be used to calculate the permissible magnitude of pulsed current in a given ac power system.