Electromagnetic drive

Electromagnetic vibrators can cover a very wide frequency range, in particular being capable of very high frequencies up to at least 104 Hz, although at this level considerable care is needed. Quite high power is obtainable, but electromagnetic drive is more commonly applied to relatively small machines and low strains. It is also used in forced oscillation methods at resonance. 

A 8] The micro injection system relies on an electromagnetic drive and injects a small volume of only 0.5 pi per injection. The valve section is heated. The injected gas pulse is separated in a thin-layer separation column. 

Fig. 7.2.8 Sil icon micromachined yaw-rate sensor with electromagnetic drive 1, coupling spring 2, magnet 3, oscillating direction 4, oscillating mass 5, acceleration sensor 6, direction of Coriolis acceleration 7, spring to...

Commercial DMA instruments vary in their design. One commercial instrument is shown in Fig. 16.36, set up for a three-point bend test under dynamic load. A different commercial instrument schematic. Fig. 16.37 shows a sample clamped between two arms that are free to move about the pivot points [Fig. 16.37(a)] the electromagnetic drive and arm/ sample assembly are shown in Fig. 16.37(b). The electromagnetic motor oscillates the arm/sample system and drives the arm/sample system to a preselected amplitude (strain). The sample undergoes a flexural deformation as seen in Fig. 16.37(a). An LVDT on the driver arm measures the sample s response to the applied stress, calculates the modulus (stiffness) and the damping properties (energy dissipation) of the material. 

The design provides for two independent and diverse reactivity control systems. The first system is based on control rods with electromagnetic drives. The second system is a liquid boron system providing for an injection of Na2B407 solution to the coolant. The reactivity control mechanism is summarized in Table X-3. 

Mechanical system 104 electromagnetic drives with 12 boron carbide based control rods per each drive Transfers core to a subcritical state without cooling down the reactor... 

Each assembly accomodatesl2 guiding tubes of 16 x 0.8 mm diameter for control rods, located within the pebble bed. They are brought together by a crosspiece and connected to the electromagnetic drive by a bar. The periphery of each fuel assembly includes 18 tubes of 11.2 X 06 mm diameter filled with water, which is needed to increase the effective amount of moderator in the area adjacent to the outlet collector (duct wall). Else, the density of steam-water mixture in this area will be 3 times lower than in the assembly on average. The inlet collectors and the duct are made of borated stainless steel and act as burnable poisons for the compensation of burn-up reactivity. They also flatten fuel bum-up in the areas adjacent to water cavities (collectors). 

The mechanical system of reactivity control is based on conventional cylindrical control rods and electromagnetic drives. It includes 104 electromagnetic drives, of which 37 drives are used to compensate reactivity changes with fuel bum-up and to flatten power distribution in the core. Of them, 12 drives are used for the automatic control of power. The remaining 67 drives combine the functions of operation control and reactor shutdown. The mechanical system is capable to bring the VKR-MT to a cold shut down state at the beginning of life (BOL) only. Later on, the operation of liquid boron shutdown system should be added to achieve this state, while the mechanical system will be capable to bring the reactor to a shutdown state only at 250°C. 

The system of spent fuel discharge from fuel assemblies includes the inlet pipeline for ball transport and a stop valve in the tail part of a fuel assembly, the electromagnetic drive of the stop valve, and an internal repository of spent micro fuel elements. 

The internal repository of spent micro fuel elements includes a silo mounted upon the reactor vessel bottom. The silo is equipped with an outlet ball pipeline aligned with the branch pipe (or with several branch pipes) located in the reactor vessel bottom. This branch pipe is used for the discharge of micro fuel elements and is connected to an electromagnetic drive. The silos are equipped with the guiding tubes, in which the bars of the stop valves of the ball transport pipelines move. The number of guiding tubes is equal to the number of fuel assemblies, i.e., 151. All structural elements of the silo are made of borated steel to ensure that the repository is subcritical. 

The outer reservoir includes a high-pressure vessel, the inlet pipeline for ball transport with a stop valve, the outlet pipeline for ball transport with a stop valve, and the stop valves with electromagnetic drives. The reservoir is also equipped with the pipelines for the supply and removal of the coolant. These are also equipped with stop valves. 

The discharge of spent micro fuel elements from fuel assembly 8 to the internal repository 7 is performed as follows. The electromagnetic drive opens the stop valve in the bottom part of fuel assembly 8. The spent micro fuel elements from fuel assembly 8 are poured out, driven by gravity, to the internal repository 7. 

With the accumulation of spent micro fuel elements in the internal repository 7, they are discharged to external reservoir 16. For this, the electromagnetic drive opens the stop valve of the internal repository 7, and the spent micro fuel elements enter the external reservoir 16 through a branch pipe 13 in the reactor vessel bottom 1. 

Figure 8.47 Principle of Mossbauer spectroscopy. An electromagnetic drive system (EDS) moves the energy source (Sj towards and awayficm the absorber (A) with a constant velocity 8. Transmitted radiation is measured by the proportional counter (Z). lead collimators (C) dejme beam geometry.

Hynek et al (1997a) describe a modified version of the fiow vibrating-tube densimeter with a photoelectric pick-up system and a new concept of an electromagnetic drive system was designed for density difference measurements in the temperature and pressure ranges from 25 to 300 and up to 35 MPa. Similar equipment was used by Hakin et al (2000). 

A simple illustration is shown in Fig. 6-5 an electromagnetic drive causes periodic shearing of two discs with shear sandwich geometry. The complex ratio of driving force to velocity is the same as that given in equations 21 to 23 of Chapter 5 ... 

Figure 6.8 Typical vibratory conveying system with electromagnetic drive.

Electromagnetic drive The third type of drive and the first non-mechanical type is the electromagnetic drive which is illustrated in Figure 6.15. The basic principle of operation for this type of drive involves the cyclic energisation of one or more electromagnets, with... 

FIGURE 2.65 Valve gate nozzle with electromagnetic drive... 

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