25-08-2017, 09:32 PM
Electro mechanical System Assignment
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Electromechanical system:
In engineering, electromechanics combines electrical and mechanical processes. Devices which carry out electrical operations by using moving parts are known as electromechanical. Strictly speaking, a manually operated switch is an electromechanical component, but the term is usually understood to refer to devices such as relays, which allow a voltage or current to control other, isolated voltages and currents by mechanically switching sets of contacts, solenoids, by which a voltage can actuate a moving linkage, vibrators, which convert DC to AC with vibrating sets of contacts, etc. Before the development of modern electronics, electromechanical devices were widely used in complex circuits, including electric typewriters and teletypes, and up to the complexity of an electromechanical digital computer.such as as mechanical electric actuators, are a requirement. Such chips have replaced most electromechanical devices, are used in most simple feedback control systems, and appear in huge numbers in everything from traffic lights to washing machines.
Application:
• Automatic transmission system:
An automatic transmission system (or occasionally automated transmission system, to avoid confusion with the automatic transmission of an automobile) is an automated system designed to keep a radio transmitter and antenna system running without direct human oversight or attention for long periodsThe system monitors conditions such as voltage, current, and temperature within the transmitter cabinet or enclosure, and often has external sensors as well, particularly on the antenna. Some systems have remote monitoring points which report back to the main unit though telemetry links, particularly for lower radio frequencies like AM radio where propagation changes from day to night.Advanced systems can monitor and often correct other problems which are considered mission-critical, such as detecting ice on antenna elements or radomes and turning on heaters to prevent the VSWR (power reflected from a mismatched antenna back into the transmitter) from going too high. High-power stations which use desiccation pumps to put dry nitrogen in to their feed line (to displace moisture for increased efficiency) can also monitor the pressure. Generators, batteries, and incoming electricity can also be monitored.
• Electric power conversion:
In electrical engineering, power engineering and the electric power industry, power conversion is converting electric energy from one form to another, converting between AC and DC, or just changing the voltage or frequency, or some combination of these. A power converter is an electrical or electro-mechanical device for converting electrical energy. This could be as simple as a transformer to change the voltage of AC power, but also includes far more complex systems. The term can also refer to a class of electrical machinery that is used to convert one frequency of alternating current into another frequency.Power conversion systems often incorporate redundancy and voltage regulation.One way of classifying power conversion systems is according to whether the input and output are (AC) or (DC).The standard power frequency varies from country to country, and sometimes within a country. In North America and northern South America it is usually 60 hertz (Hz), but in many other parts of the world, is usually 50 Hz.
• Electromechanical meters:
The electromechanical induction meter operates by counting the revolutions of a non-magnetic, but electrically conductive, metal disc which is made to rotate at a speed proportional to the power passing through the meter. The number of revolutions is thus proportional to the energy usage. The voltage coil consumes a small and relatively constant amount of power, typically around 2 watts which is not registered on the meter. The current coil similarly consumes a small amount of power in proportion to the square of the current flowing through it, typically up to a couple of watts at full load, which is registered on the meter.
• Relay :
A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits, repeating the signal coming in from one circuit and re-transmitting it to another.
• Stepping Switch:
In electrical controls, a stepping switch or uniselector (UK), also known as a stepping relay, is an electromechanical device which allows an input connection to be connected to one of a number of possible output connections, under the control of a series of electrical pulses.It can step on one axis (called a uniselector), or on two axes (a Stronger switch). Stepping switches were invented by Almon Brown Strowger in 1888. The major use for these devices was in early automatic telephone exchanges (commonly called Strowger or step-by-step exchanges or steppers) to route telephone calls. Later, they were often used in such equipment as industrial control systems.
• solenoid valve:
A solenoid valve is an electromechanically operated valve. The valve is controlled by anelectric current through a solenoid: in the case of a two-port valve the flow is switched on or off; in the case of a three-port valve, the outflow is switched between the two outlet ports. Multiple solenoid valves can be placed together on a manifold.Solenoid valves are the most frequently used control elements in fluidics. Their tasks are to shut off, release, dose, distribute or mix fluids. They are found in many application areas. Solenoids offer fast and safe switching, high reliability, long service life, good medium compatibility of the materials used, low control power and compact design.
Explanation:
I meant the north end of a bar magnet pointing down with another bar magnet some distance below it with it's south pole pointing upwards. I guess by outside of the magnetic field they mean away from the edge of the magnets and the fringe effect. The way I described my rectangular path is the hint they gave in the textbook. "Bh" is the vertical side inside the field, and the term for the other vertical side disappears because B = 0.
So there are two bar magnets in series. Even so, the B field does not go to zero for that system except at infinity or with ideal magnetic field shielding. Something is missing here..
BTW, the "fringe effect" comes into play when you are working with calculating the capacitance of a finite size capacitor, not some magnetic geometry, IMO.
In the most of the rotating electrical machines (DC orAC), the windings of the stator or rotor are taken into open mouth slots. Slot shapes and their mouths opening are depending on the type of the machine and its operation. The quantity of the scattered flux is mainly depends on the slot mouth opening, and the slot shape have small effect. So the slot shapes are chosen rectangular. In the AC machines having sinusoidal flux distribution, the slots number must be
chosen greater, and the slot opening smaller. This condition cannot be taken in fact. As shown in Fig. 1, in this condition the flux density of the air gap of the machine is reduced strongly in front of the slots, and distorted from the sinusoidal shape Different methods are given in many designing references for specifying and calculating of the effective air gap length.