Damper bars

Some generators have the damper bars connected to a ring at either end of the pole structure, which provides some damping action from the quadrature axis. This provides a set of short-circuited coils in the quadrature axis, which are air cored and able to repel the flux that is attempting to enter their region. 

The damper bars or winding act in a manner very similar to an induction motor and provide a breaking torque against the transient disturbances in shaft speed. To be effective the damper needs to have a steep torque versus shp characteristic in the region near synchronous speed. The equivalent impedance of the damper requires a low resistance and a high reactance. High conductivity copper bars are embedded into the pole face to provide a low reluctance path for the leakage flux. 

The synchronous rotor carries the rotating independently excited field windings of the machine. For good control response, these must be fed with DC current via slip rings and these must be correctly sized for the low speeds and stall duties required by a hoist. The synchronous motor rotor will comprise of wound poles, pole bolting system, damper bars, slip rings/brush-less excitation and interconnections. 

Schieber, m. slide, slider, slide bar, slide valve, carriage shovel pusher, shover damper, -kasten, m. (Mach.) slide box, valve chest. 

We will learn more about the plucked string and higher-dimensional vibrating systems such as bars, plates, membranes, etc., in later chapters. The point of introducing the example of the plucked-string system here was to motivate the notion that sinusoids can occur in systems more complex than just the simple mass/spring/damper. 

The front suspension is the torsion bar spring, double-cylinder inflatable hydraulic damper, transverse stabilizer rod, double cross-arm independent suspension. The distance between the center of front shaft of lower arm fixing nut and level grormd is 295mm+lmm. 

Left-right swing/up-down bounce The tyre is charged improperly The stabilizer bar is bend or damaged The vibration damper is worn Charge the tyre to the proper pressure Replace the stabilizer bar Replace the vibration damper... 

Some of the larger production machines built in the United States— that is, those that exceed 30 m (100 ft.) in length and 1.27 m (50 in.) in width—have been built with a series of chambers, each of which uses air inlet sparging bars and exhaust bars at the opposite end. These systems provide for the countercurrent airflow over the drying tape and also are quite readily adjustable using damper valving mechanisms at either the inlet or the exhaust or both. 

Plane frame structures, treated as elastic systems with VE dampers, are modelled using the finite element method. A two-node bar element with six nodal parameters is used to describe the structure. The mass and stifihess matrices together with the vector of nodal forces of the element can be found in many sources. The equation of motion of a stmcture with VE dampers modelled using the generalized rheological models can be written in the following form ... 

In order to illustrate the general results obtained previously, we consider a two bar linkage with linear torsional springs and dampers at the joints, and with a stochastically varying follower force P(t) = (1 + f(t))... 

The simplest mechanical models for viscoelastic behavior consist of two elements a spring for elastic behavior and a damper for viscous behavior. First it is convenient to introduce the model of a linear spring to represent a Hookean bar under uniaxial tension where the spring constant is the modulus of elasticity. As indicated in Fig. 3.19 the spring constant can be replaced by Young s modulus if the stress replaces P/A and strain replaces 6/L. 

By summing the dy and the axial elastic deformation of the steel bars that function as auxiliary elements, the total axial displacement of the brace damper at yielding, dry, is obtained. The later contribution can be approximated hyfauJ I E, where L is the total length of the brace damper soldi faux is the normal stress in the cross-section of the steel bar caused by the axial force Qry, that is ... 

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