Logic Families in Digital Electronics - TTL, CMOS, and ECL

Most electronic systems which are responsible for modern advances are based on digital technology. All digital systems, computers and microprocessors are assembled from simple circuits called logic circuits. The basic building blocks of logic circuits are logic gates. And logic gates themselves are simple electronic circuits comprising of diodes, transistors and resistors.

Mechanical, Electrical, Plumbing (MEP) in Construction Contract

The acronym MEP became an integral word of a building project in Middle East Gulf region during year 2000. In the inception stage of MEP, there were involvement of only two engineering branches, Mechanical and Electrical, now it included electronics, instrumentation and communication. In some occasions, Mechatronics also partake in the project for smooth completion of the whole MEP works. Companies that carry out MEP works also known as Electro-Mechanical company which has multi-faceted technicians and engineers for effective design, coordination and execution of the works.

Method Statement For Installation Of Cable Tray Or Trunking

Electrical Engineers seldom show interest acquiring knowledge and experience on cable tray installations. Most of them think it's a concern of mechanical fabricators to be taken care of it. A proper and professional way of cable tray installation requires good involvement and coordination of people from both electrical and mechanical disciplines. If cable tray system has been installed appropriately in a project, following advantages can be counted:

  • Cable Tray system enhances safety of electrical wiring system.
  • Cable tray installation provides dependability in any circumstances.
  • Cable Tray system saves space, materials, labor, time and cost.
  • Maintenance and extension of cable tray installation are easier than any other wiring system.

Hence, electrical installation of a project must give high priority to adopt properly evaluated cable tray wiring system if aesthetic impact is low. This article explains how to make a typical method statement for cable tray or trunking installation for a building project.

Method of Earthing or Grounding for Diesel Generator Plant

Earthing or Grounding of Diesel Generator Plant is important to ensure correct operation of the plant and safety of the people who work over there. Generator neutral (star point) is to be connected by insulated earthing conductor through the neutral earthing link or device to main earthing bar. Neutral earthing conductor is to be suitably sized to carry maximum earth fault current for time it takes the system protection to operate with final conductor temperature not exceeding 160 deg. C, but not less than 30 mm2 per 100 kVA of generator rating, with a minimum of 50 mm2. All emergency power diesel gensets including portable gensets to be connected to grounding conductor.

Also read: Guidelines for installing emergency power diesel genset.

Earthing or Grounding Method For Transformer Substation

MV switchgear and MV cables are to have separate main earthing bar connected to framework or earth bar of each item by insulated conductor and the earth-electrode by 2 insulated earthing conductors, one at each end of bar, via testing joints. Earthing conductor is to be minimum 150 mm2.

Testing and Commissioning In Electrical Construction Works

At the completion of the electrical installation works, the entire installation shall be subject to the test before final placing in service under the full responsibility of the contractor. Unless Otherwise specifically called for all tests shall be carried out in conformity with IEE regulations. Contractor shall coordinate with the Client and the Supervising Engineer to get electricity from the local supply authority before starting of testing and commissioning.

Master Antenna TV System (MATV) In Electrical Construction Works

Master Antenna Television or MATV means many TV connection outlets from one Master antenna control system. Usually high-rise apartment houses, hotels, schools and cluster based residential area utilizes this kind of TV distribution network. It may or may not include FM radio so that one outlet can receive both TV and FM reception. The scope of this section covers the design, supply, installation, testing and commissioning of Master Antenna TV System, for the reception and distribution of television broadcast signals.

Typical Details For Cable Tray Installation And Support System

Below drawing shows how to install cable tray and its support system. This cable tray support system drawing has Isometric view and cross-sectional view. Following are the steps to be done for laying cables on wall mounted cable tray:

  1. Install cable tray support using a pre-fabricated flange or GI channel. The size, length and intervals of the support to be as per the specification, standards, number of cables, and size of the cable.
  2. Fix the cable tray as shown on the drawing.
  3. Lay the cable keeping the distance as per calculation.
  4. Tie the cable using cable tie and label the cables as required.

Method of Clean Earthing or Grounding in Electrical System

Clean earth grounding or low noise earth shall be provided as required, to ensure that the level of induced or conducted interference from external sources, including the facility power grounding system, does not produce incidence of malfunction of the equipment, which is unacceptable for the operating system. The electronics systems must be protected by providing a network path having low impedance for interconnecting its equipment.

Proper routing, zoning and shielding of the cables / earth wires are important and must serve the purpose of preventing sources of electrical disturbances from the operation of electrical equipment.

Execution Method of Electrical Earthing or Grounding Installation

Continuity: Ensure that complete earthing system is electrically continuous and mechanically secure. Locations of main earth bars in substations, electrical rooms, mechanical rooms, hub (Technical) rooms, etc., to be clearly identified by 100mm X 100mm white traffolyte labels, with red lettering, to Engineer's approval.

Method of Lightning Protection System For Building

Comply with the General Conditions, Supplementary Conditions and the requirements in various Sections of the Electrical Specification. In addition read and conform to all Electrical Sections of these specifications. The installation shall comprise air networks connected to roof and down conductors and finally terminated in earth electrodes, via structural re-bars and suitable test points in accordance with the details included on the attached drawings or in the Specification Section.

Electrical Earthing or Grounding Electrode Design for Building Construction

Earthing or Grounding Electrode for an effective and reliable electrical earthing system requires proper survey and analysis of project location, type of structures installed and electrical / electronic equipment used in the entire system. The design calculation of the earth electrode systems shall be based on the approved earth resistivity data and the system's fault currents and their duration.

Typical Cable Laying Details For Direct Buried, Low Tension Cables

Most Construction projects requires underground cabling system for its power supply, some times High tension system too. The architects and builders are least bothered about how this cables routed to the premises and equipment. If electrical professionals pointed out the feasibility, the aesthetics of the project would touch to the intended level. Hence, in the planning stage itself the routes and size of the power cable trench to be incorporated in the project design.

Wiring Materials And Installation Methods in Electrical Construction Works

Electrical wiring needs expertise attention to every building projects. It directly related to the safety of human beings and utilities / equipment people handle. The scope of electrical wiring shall cover supply, installation, testing and commissioning of all conduits and accessories, wiring, switches, socket outlets, spur outlets, junction boxes / pull boxes, GI pull wires, ceiling roses making connections etc. This Electrical Construction Article gives comprehensive details of various installation methods, materials used in each installation methods used in building construction projects.

Method of Earthing or Grounding Of MDB, Panel Boards, Lighting And Wiring Installations

Method of Earthing To Main Distribution Board (MDB)

Main earthing bar is to be provided in main distribution room and connected to earth electrode by 2 insulated conductors (minimum 150 mm2) via testing joints. Earthing bars of main distribution boards are to be connected, by insulated earthing conductor, directly to main earthing bar at main distribution room.