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ممكن معلومات عن relay

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  1. [1]
    zaid alkhalidi
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    ممكن معلومات عن relay

    السلام عليكم ممكن الحصول على معلومات عن ال relay اشكاله طريقة عملة انواعه ولكم مني جزيل الشكر

  2. [2]
    razasavari
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    ممممشششششششششششششششششششششششششکککککککککککککککککککوو وووووووووررررررررر

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  3. [3]
    zaid alkhalidi
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    يا اخي على ايه الشكر هههههههههههههه
    اني الي طالب المعلومات ممكن اتوفروها لي

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  4. [4]
    hegoo
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    اخى العزيز اقدم لك بعض المعلومات البسيطة عن ال Relay وارجو ان تنال رضائكم وقد استطعت تقديم شئ بسيط لمساعدتك .

    A relay is an electrically operated switchElectric current through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. The coil current can be on or off so relays have two switch positions and they are double-throw (changeover) switches.

    Basic design and operation:

    A simple electromagnetic relay, such as the one taken from a car , is an adaptation of an electromagnet. It consists of a coil of wire surrounding a soft iron core, an iron yoke, which provides a low reluctance path for magnetic flux, a movable iron armature, and a set, or sets, of contacts . The armature is hinged to the yoke and mechanically linked to a moving contact or contacts. It is held in place by a spring so that when the relay is de-energised there is an air gap in the magnetic circuit. In this condition, one of the two sets of contacts in the relay is closed, and the other set is open. Other relays may have more or fewer sets of contacts depending on their function. The relay also has a wire connecting the armature to the yoke .
    When an electric current is passed through the coil, the resulting magnetic field attracts the armature, and the consequent movement of the movable contact or contacts either makes or breaks a connection with a fixed contact. If the set of contacts was closed when the relay was de-energised, then the movement opens the contacts and breaks the connection, and vice versa if the contacts were open. When the current to the coil is switched off, the armature is returned by a force, approximately half as strong as the magnetic force, to its relaxed position. Usually this force is provided by a spring, but gravity is also used commonly in industrial motor starters. Most relays are manufactured to operate quickly. In a low voltage application, this is to reduce noise. In a high voltage or high current application, this is to reduce arcing.

    Types of relay :

    1 - Latching relay: A latching relay has two relaxed states (bistable). These are also called "impulse", "keep", or "stay" relays. When the current is switched off, the relay remains in its last state. This is achieved with a solenoid operating a ratchet and cam mechanism, or by having two opposing coils with an over-center spring or permanent magnet to hold the armature and contacts in position while the coil is relaxed, or with a remanent core. In the ratchet and cam example, the first pulse to the coil turns the relay on and the second pulse turns it off .

    2-Reed relay : A reed relay has a set of contacts inside a vacuum or inert gas filled glass tube, which protects the contacts against atmospheric corrosion. The contacts are closed by a magnetic field generated when current passes through a coil around the glass tube. Reed relays are capable of faster switching speeds than larger types of relays, but have low switch current and voltage ratings.

    3 -Mercury-wetted relay : A mercury-wetted reed relay is a form of reed relay in which the contacts are wetted withmercury. Such relays are used to switch low-voltage signals (one volt or less) because of their low contact resistance, or for high-speed counting and timing applications where the mercury eliminates contact bounce.

    4 - Polarized relay : A Polarized Relay placed the armature between the poles of a permanent magnet to increase sensitivity. Polarized relays were used in middle 20th Century telephone exchanges to detect faint pulses and correct telegraphic distortion.

    5 - Machine tool relay : A machine tool relay is a type standardized for industrial control of machine tools, transfer machines, and other sequential control.

    6 - Contactor relay : A contactor is a very heavy-duty relay used for switching electric motors and lighting loads. Continuous current ratings for common contactors range from 10 amps to several hundred amps. High-current contacts are made with alloys containing silver. The unavoidable arcing causes the contacts to oxidize and silver oxide is still a good conductor. Such devices are often used for motor starters. A motor starter is a contactor with overload protection devices attached. The overload sensing devices are a form of heat operated relay where a coil heats a bi-metal strip, or where a solder pot melts, releasing a spring to operate auxiliary contacts.

    7 - Solid-state relay :

    8 - Overload protection relay : One type of electric motor overload protection relay is operated by a heating element in series with the electric motor . The heat generated by the motor current operates a bi-metal strip or melts solder, releasing a spring to operate contacts. Where the overload relay is exposed to the same environment as the motor, a useful though crude compensation for motor ambient temperature is provided.

    9 -Buchholz relay : A Buchholz relay is a safety device sensing the accumulation of gas in large oil-filled transformers, which will alarm on slow accumulation of gas or shut down the transformer if gas is produced rapidly in the transformer oil.

    Applications :

    - Control a high-voltage circuit with a low-voltage signal, as in some types of modems or audio amplifiers .
    - Control a high-current circuit with a low-current signal, as in the startersolenoid of an automobile .
    - Detect and isolate faults on transmission and distribution lines by opening and closing circuit breakers (protection relays) .
    - Isolate the controlling circuit from the controlled circuit when the two are at different potentials, for example when controlling a mains-powered device from a low-voltage switch. The latter is often applied to control office lighting as the low voltage wires are easily installed in partitions, which may be often moved as needs change. They may also be controlled by room occupancy detectors in an effort to conserve energy .
    - Early computing. Before vacuum tubes and transistors, relays were used as logical elements in digital computers.
    - Safety-critical logic. Because relays are much more resistant than semiconductors to nuclear radiation, they are widely used in safety-critical logic, such as the control panels of radioactive waste-handling machinery.

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  5. [5]
    أبو هند و ساره
    أبو هند و ساره غير متواجد حالياً
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    تاريخ التسجيل: Sep 2009
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    ارجو زيارة هذا الموقع
    http://en.wikipedia.org/wiki/Relay

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    لا إله إلا أنت سبحانك إني كنت من الظالمين

  6. [6]
    zaid alkhalidi
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    تاريخ التسجيل: Mar 2009
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    شكرا لكم اخواني معلومات قيمة

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  7. [7]
    محمد سعادة
    محمد سعادة غير متواجد حالياً
    عضو فعال


    تاريخ التسجيل: Aug 2005
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    هل تقصد ريليهات الوقاية ام ريليهات التحكم ؟؟

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  8. [8]
    zaid alkhalidi
    zaid alkhalidi غير متواجد حالياً
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    ريليهات التحكم وشكرا لك

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  9. [9]
    البهلول غرودة
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    الريليه في نظام الوقاية لشبكة القوي الكهربائية له اشكال متعددة وفوائد متعددة منها :
    1-ريليه للحماية من زيادة التيار2- للحماية من الخطا الارضي 3- للحماية من ارتفاع الجهد 4- للحماية من انخفاض الدبدبة 5- للحماية من اعادة التوصيل 6- للحماية من الاعطال الداخلية في محولات القدرة 7-لمقارنة التيارات الداخلة والخارجة للكوابل الارضية -------- وهكدا وكل ريليه يتم توصيله بطريقة خاصة وبقيم تيارات مناسبة 1 امبير او 5 امبير او قيمة اخري صغيرة عن طريق محولات التيار الكبيرة200 -400 -1000-امبير مثلا ومنها الديناميكي والاستاتيكي

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