Derating rotors

The performance of a motor is greatly influenced by a voltage unbalance in the supply system. It reduces its output and torque and results in a higher slip and rotor loss. This subject is covered in more detail in Section 12.2(v). For likely deratings, refer to Figure 12.1. Asystem with an unbalance of up to 1 % or so calls for no derating, whereas one having an unbalance of more than 5% is not recommended for an industrial application, because of a... 

Table 5.3 shows the derating values and Figure 5,9 the derating curve. The variation in the rotor current is also in the same proportion as the torque. 

A summary of the report follows The problem is to separate proteins. Furthermore, SpinPro should pay particular attention to the purity of the separation. The sample is not negatively affected by sucrose, has a sedimentation coefficient of 16 Svedbergs, and is in liquid form of 3 mL and a concentration of 1% w/w. The protein of interest should be placed 45% from the top of the gradient at the end of the run. Of the gradient concentrations 10-40% and 5-20%, the 10-40% is preferred by the investigator. There are no solvents in the sample that are harmful to the tubes. Finally, from the lab, SpinPro should use the L2-75B ultracentrifuge and the SW 41 Ti rotor, which does not require a speed derating due to its age. 

Selected lab centrifuge L2-75B Selected lab rotor SW 41 Ti Rotor derated No... 

The high impedance of the parallel resonance circuit is transformed to 50 Q nominally by the second variable capacitor. Both variable capacitors are Johan son 5341 which are piston air capacitors with Be-Cu stators and Ag rotors. They work very nicely except for the problem of high voltage breakdown. The dc breakdown under test conditions is listed as 1200 volts at sea level but that number has to be severely derated for radio frequency and altitude. (The latter problem is serious at Los Alamos where the atmospheric pressure is 590 mm Hg and the altitude correction to the breakdown is about 10%.)... 

In general, vertical or angled rotors are used, and the speed at which they are used is normally calculated from the maximum speed of the rotor, multiplied by a derating factor calculated from the specific gravity of the contents of the tube. For CsCl gradients this is normally 0.77 (3). Further derating may be applied to particular rotors, because of their age and previous history (3). 

Be sure to follow all manufacturer s recommendations on the use and maintenance of the rotors and instruments. Instruction manuals and rotor manuals must be made available for reference. Pay particular attention to the requirement for derating run speeds based on solution density. Rotors are also derated based upon total use hours. Keep derating information available by noting it on the rotor inventory list, on the rotor card (used to maintain data on rotor use), and by marking the information on the base of the rotor stand for those rotors that have stands. Also change the overspeed device ... 

Provide an instrument log book for each instrument to record data about each run, including aborted runs. One method is to use a unique run identifying number for each machine since rotors may be used in various machines. A different sequential number for each instrument can be used (e.g., 4-273 can indicate run 273 in instrument 4). Record both the rotor type used and its serial number in the log book. A complete record will include an indication of whether or not a run-derate calculation was required and whether a spill occurred during the run. A Remarks space should be available to record any information about problems or unusual instrument behavior, or to record notes to the service person. 

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