Unbalances sources

FIG. E-4 Motor loss percentage as a function of voltage unbalance. (Source Reliance Electric.)... 

The top and the bottom x-ray detector each contain a multiplier phototube coated with phosphor. This tube compares the intensity of the x-ray beam entering the detector with that of the light from the reference standard, a discharge lamp. The reference beam is part of a circuit that maintains the x-ray source at constant intensity. The deviation wedge comes to rest when the intensities of the transmitted x-ray beams stand in a predetermined ratio. At this point, the unbalance in the servo system has been compensated, and the position of the deviation wedge consequently indicates the thickness of the strip. In 1955, this application was made fully automatic that is, the unbalance (or error signal) just mentioned was used to readjust tandem cold reduction mills of the United States Steel Corporation. Automatic control proved significantly more effective than manual control. 

For one thing, steam produced from hot-lime-softened water will have some amount of silicates. These silicates tend to deposit on the rotor blades of turbines, which use the motive steam as a source of energy. The silicate fouling of the turbine blades reduces the turbine s efficiency. But, more importantly, from an operator s point of view, the silicate deposits eventually break off of the blades. This unbalances the rotor. An unbalanced rotor is the fundamental cause of vibration, Vibrations lead to damage of the shaft bearings and seals. Eventually, vibrations will destroy the turbine s internal components. 

Undesired vibrations and shocks may originate from a wide variety of sources, such as unbalance and reciprocal motions in mechanical machinery, aerodynamic turbulence, rough sea movements, earthquakes, road and rail transportations, and tough handling of equipment. 

Common mode rejection ratio (CMRR) CMRR of a differential amplifier is defined as the ratio between the amplitude of a common mode signal and the amplitude of a differential signal that would produce the same output amplitude or as the ratio of the differential gain over the common mode gain CMRR = GD/GCM. Expressed in decibels, the common mode rejection is 20 log 10 CMRR. The common mode rejection is a function of frequency and source impedance unbalance. 

A structural fault noted Fs corresponds to a new effort (or flow) source that causes a change in the structure of the model. Thus, the nominal model of the system is not conserved and its dynamic is altered by the presence of the fault. This difference between the system and the model generates an unbalance in the flow, mass and energy conservation laws, calculated from junctions 0 and 1 of the bond graph model. For example, a water leakage in the tank of Fig. 3.15b is a stfuctural fault. It can be modeled by a flow source Sf Yg. The model sfructure has changed from the bond graph model of the system without fault of Fig 3.15a. 

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