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Power Semiconductor Switches

 Power Semiconductor Devices in Power Electronics Power electronics refers to control and conversion of electrical power by power semiconductor devices whereby these devices operate as switches. Power electronics run over a broad field of application such as in drives applications, Switch-mode power supply (SMPS), aviation electronics, high frequency inverters and power electronics, Electric power transmission, Automotive electronics, Uninterruptible power supplies (UPS), Alternative power sources controllers  etc. Power Semiconductor Devices (Switches) Power switches operates in two states (modes). This is shown in the figure 1 below: -  ON state (Conducting mode): this is when the switch closed.   -  OFF state (Blocking state): this is when the switch is opened. Figure 1: switching states of a power semiconductor switch Note: Power switches don’t operates in linear mode. Classification of Power Switches Power switches are classified in three groups. Namely: -...

Download HND questions Cameroon for Electrical engineering, physics, Mathematics

 2021 HND Questions for Electrical Engineering The download file contains the following 2021 papers mentioned below with their various specialties File 1 include: - Circuit Theory: Specialty Electrical Power System (EPS) - Circuit Theory and Control Engineering : Specialty Industrial Computing and Automation (ICA) and Hardware Maintenance (HM) - Electrical Machines : Specialty EPS - Electrical Power System: Specialty EPS - Industrial Chemistry: Specialty Electrotechnics (ELT) and EPS - French Language : All Specialties DOWNLOAD FILE 1 HERE File 2 include: -  Case Study:  Electrical power system (EPS) - Engineering mathematics: For All engineering Specialties (CET, UPL, BST, CAR, JOC, RCE, MEM, CHM, CHP, ELT, EPS, ACR, PSE, CNS, HWM, BMW, PCH, TOP) - Physics for Engineers: Specialty (CET, BST, CAR, JOC, RCE, MEM, ELT, EPS, ACR, BMW, TOP) - Computer Studies: All Specialties  - Law and Citizenship: All Specialties - Enterprise Creation and Entrepreneurship: All ...

Direct On Line Starter wiring diagram forward and reverse automatic starting

Direct On Line semi-automatic Starting forward and reversed rotation Direct on line starting is a method generally used to start three phase induction motors with power less than or equal to 10KW. Circuit diagram of direct on line starting: The circuit diagram is divided into the the Power Circuit and Control circuit shown below. Operating principle: When the fuse isolator is closed, an action on the start push button S2 energises the contactor KM1 which closes the main contacts of the contactor, closes its hold on contact, opens the interlock on kM2 (so that KM2 should not be energized) and closes the open contact of KM1 to which the lamp H1 is connected. The motor rotates in the forward direction and the lamp H1 shines which indicates the motor is running in the forward direction. To reverse the direction of rotation of the motor, the motor must first be stopped by pressing S1. For reverse rotation, an action on the reverse push button S3 e...

WHAT IS A MULTIPLEXER?

  MULTIPLEXER we are going to see more complex combinational logic circuits or combinational devices which are the multiplexer and demultiplexer. These devices are can be found as integrated circuits (ICs) and are widely used in the field of telecommunication like in multiplexing. WHAT IS A MULTIPLEXER? A multiplexer also called data selector is a device that selects one of many input signals and forwards the selected input to the output. A multiplexer of 2 n inputs has n select bits, which are used to select which input line to send to the output.   See figure 1. An electronic multiplexer makes it possible for several signals to share one device or resource like one communication line instead of having one device per input signal. An example can be in a cyber where many computers are connected to the same printer, another example is an mp3 player, laptop, digital cable TV connected to a single surrounding sound system through a Mux.  

Operation of a Hydroelectric Power Station

How a Hydroelectric power Station Works A hydroelectric power plant is a power station which produces electrical energy from the energy stored in water at certain heights, with the use of a turbine which is mechanically coupled to a generator.  So water is the primary source of energy in this type of power plant. In order to understand the conversion process, we shall chronologically study the different components and their role in the conversion process. The diagram below is a schematic diagram of a hydroelectric power plant. Layout of a hydroelectric power plant