Electrical engineering

Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics, and electromagnetism

Electrical engineering has now subdivided into a wide range of subfields including electronics, digital computers, power engineering, telecommunications, control systems, radio-frequency engineering, signal processing, instrumentation, and microelectronics

Electricity has been a subject of scientific interest since at least the early 17th century

Power engineering deals with the generation, transmission and distribution of electricity as well as the design of a range of related devices

Saturday, July 11, 2015

البيوت الذكية

هل سمعت عن البيوت الذكية ؟


يحلم العلماء والمعماريون والمهندسون ، وأشهرهم المهندس المعماري الألماني ” هيوبرت فرتيز ” ، والذي يعد من العلامات البارزة في العمارة الألمانية والأوروبية بوجه عام ، بالبيت الذكي الذي يجد الإنسان فيه راحته ، حيث يُمكن إعادة تشكيله بسهولة لدفع الملل عن نفوس ساكنيه ، ولا يستخدم أية طاقة صناعية على الإطلاق ، بل يعتمد على الطاقة المتجددة فقط ..
وهذا الحلم يشغل أذهان المهندسين والمعماريين في أنحاء العالم ، فالبيت ذو الاستهلاك المنخفض للطاقة ، أو البيت الإيجابي ، أو البيت فوق العادة ، كلها في النهاية أسماء متعددة لمسمى واحد وهو البيت الذي يحتاج فقط نسبة ضئيلة من حرارة التسخين أو الكهرباء التي تستهلكها البيوت التقليدية في الوقت الحالي
وحسب الرؤية التي يتبناها ” فرتيز ” ، فإن البيت لا يستحق أن يندرج تحت المسميات السابقة إلا إذا كان استهلاكه للكهرباء يقل عن استهلاك البيوت المماثلة التقليدية بنسبة 40 % على الأقل ، وهذا الأمر يُمكن أن يتحقق من خلال ما يلي:
أولا: بجدران جيدة العزل تمنع تسرب الطاقة الى خارج المنزل قدر الامكان
ثانيا:هو الاستغلال الأمثل للطاقة الشمسية
ويؤكد المهندس الالماني على أهمية استخدام الطاقة الشمسية والرياح والماء والغاز العضوي (البيوجاز)

وبالتالي البيوت الذكية .. هي ثمرة جديدة من ثمار التقدم العلمي ، وهي عبارة عن شقق وفيلات يستخدم فيها أحدث ما وصلت إليه التكنولوجيا ، فهي تدير ظهرها للشمس صيفا وتستقبلها في الشتاء !!
وبها شبكة معلومات متكاملة تنبه الساكن لدرجة الحرارة ، وتحميه من الأمراض ، والتيار الكهربائي بها ينقطع تلقائيا ، والنوافذ تفتح وتغلق عند حلول النهار والليل ، ومنازل هذا القرن أخشابها لا تحترق وتقاوم الفطريات ، وتحمي نفسها من اللصوص والحيوانات الضالة ..
وتم عمل أول بيت ذكي في ألمانيا عام 1991 في كامشتاد ونجد هذا النوع من البيوت يجد اقبالا متزايدا اليوم

EIB Components




  EIB Components




EIB devices are divided into three types according to their use:




  1. Basic components, such as power supply unit (PSU), choke, and signal filter.
  2. System components, which support the basic operation of the system such as Bus Coupling Unit (BCU), Line Coupler (LC), Phase Coupler, Repeater.
  3. EIB devices which are dedicated to applications such as sensors, actuators, IR decoders, display panels. These types of devices are connected to EIB by a Bus Coupling Unit or similar interface.




*         Power Supply Unit (PSU)




The power supply unit provides power for feeding of EIB Bus devices (Safety Extra Low Voltage (SELV), 30 V DC nominal).




*         Choke




The choke provides the coupling of the Power Supply Unit to the data bus line.






*         Data Rail




The data rail is a Mounted support with four tracks to distribute the bus onto DIN rail.




*         Data Rail Connector



The data rail connector provides the connection between the bus cable and the data rail.

 

FIG.1






*         Bus Coupling Unit (BCU)

The BCU is available as an EIB standard product or the functionality may be integrated directly in the product. As it is shown on Fig.1 the BCU is composed of:

1.     A transceiver: a module which provides:
-          Bus coupling of the device by sending data signals onto the medium and decoding received signals.
-          Optional a DC power conversion for the BCU, for the receiver and transmitter function, for output signal generation.

2.     A communication controller.

3.     A microprocessor which provides:
-          Necessary communication features
-          Optimal application routing
-          Physical External Interface (PEI) support
-          Operating system
-          Space for a program


*         The Line Coupler (LC)

 The Line Coupler is a system component for Twisted Pair. It uses the same basic functions as the repeater, but it connects the line to which it belongs to the main line. The line coupler ensures data packets routing and buffering with overflow management going from a line to the main line and vice versa. The power feeding of the LC comes from the line it belongs to. The LC provides galvanic separation.

*         The Repeater

 The repeater as well is a Twisted Pair system component. Its function is to regenerate the electrical network signals and to separate the bus access. The repeater makes it possible to connect electrical segments together and create large extended lines without back feeding effects from one electrical segment to the other. By use of repeaters more than 64 devices per line can physically be connected and more than 1000m overall wire length is allowed.

EIB Bus devices are generally built up from two parts: the Bus Coupling Unit and the application module.

The Bus Coupling Unit is a decentralized bus manager in each device and provides electrical features as well as data coupling to the Bus, in order to allow the separation of application hardware and software from the Bus communication system.

From the installation point of view the EIB Bus devices can be divided into 4 groups:

  1. Rail-mounted EIB Bus devices (for applications like load switching, analog input, binary input, IR-decoder) for controlling of appliances such as brightness sensors, anemometers, humidity sensors, temperature sensors.
  2. Flush mounted: where the Bus Coupling Unit is mounted in the wall for monitoring purposes and the application module snapped onto it outside the wall (like pushbutton, sensor, IR-decoder, set-point control, display panel).
  3. Surface mounted EIB Bus devices: where both the Bus Coupling Unit and the application module are mounted outside the wall.
  4. Device mounted: for incorporation into appliances such as heaters, lamps, etc...


Tuesday, July 7, 2015

كتاب لف المحركات

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The EIB Protocol

  The EIB Protocol

  •  Structure of Data Packet

The information exchange between two devices is achieved by transmission of data packets. Each data packet must be acknowledged. For every medium, the message frame looks similar like in Fig (1)


 

fig(1)

Some media will precede or follow this message by some medium specific sequences, characteristic for its medium access control or error correction mechanisms.

The data packet (see Fig (2) ) contains the following fields:

-          Control field
-          Source address field
-          Destination address field
-          Length
-          LSDU (Link Service Data Unit) -i.e. info to be transferred-
-          Check byte

In the case for example of a failure detection message or any other urgent message, the EIB system allows a transmission priority to be assigned to the transmission of the data packets. Alarm messages may have priority over all other messages sent in normal operation mode. Retransmitted data packets have also higher priority than normal packets.

 

fig(2)

  •   Addressing Mode

Management of EIB Bus devices connected to the Installation Bus can be addressed using two modes:

-          Physical addressing (system operation)
-          Group addressing (normal operation)

Every bus device is identified by a unique physical address. Two EIB Bus devices should not have the same physical address. The physical address consists of a zone, line and EIB Bus device number; it corresponds to the device as a whole. The source address field always contains the physical address. The physical address is only used as destination address for initialization, programming and diagnostic operations (connection oriented transmission). This corresponds to a system access mode.