However, there does exist the probability of a power failure on one of the feeds, resulting in the opening of a circuit interrupter and an unbalance in the magnetic torques acting on the array. To establish an order of magnitude of this unbalance, the effect of opening a secondary and a primary feeder on the lateral flow arrangement was examined. It was found that the effect of opening a secondary feeder results in an unbalance torque of between one and two newton - meters (0. 75 - 1.5 ft. lbs. ), while the effect of opening a primary feed is a torque of 1.45 n-m (1.07 ft. lbs.). These torques are negligible compared with other disturbances (see Section 8). 5.5 DC TO RF CONVERTER PROTECTION In microwave radar and communications applications considerable effort is devoted to protecting the individual rf tube from damage. Typical protection sensing device parameters are given below. Typical RF Tube Protective Sensing Device Parameters a. High gas pressure b. High cathode voltage c. Excessive body current d. High average beam current e. High VSWR in output waveguide f. Arcing in output waveguide g. Overtemperature sensing h. Excessive rf drive i. rf drive interlock Protection is generally necessary and justified because the rf output device typically represents the largest cost item and one of the most sensitive elements for catastrophic failure resulting as a secondary failure from faults in other parts of the system. The same strategy of tube protection should not be applied in MPTS. First, the large number of tubes has resulted in a relatively low tube cost, such that it is not economical to provide protection on a one to one basis. Secondly, the long life and the goal of minimal maintenance requires a system
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