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.

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.

Grounding or Earthing System In Electrical Construction Works

The scope of work shall cover providing grounding stations, laying copper ground wires and connecting the panels, equipment, etc. to the ground grip as shown in the drawing.

Earth / Ground Station

The ground station shall be as shown in the drawing. The ground electrode shall be minimum 10 feet long 1 inch dia steel pipe with copper weld exterior surface. The ground resistance shall be maintained with a suitable soil treatment as shown on drawings or as discussed and decided at site.

The resistance of each ground shall not exceed 2 ohms.

The ground wire shall be fixed to the rod with a clamp and safety set screws. The clamp shall be permanently accessible. Manholes with proper covers shall be provided.

Ground connections shall be of the bolted type on the top of the rod.

Definitions of Electrical Earthing / Grounding Terms

In electrical projects, both construction as well as maintenance, the following terms used on the Drawings, Specifications and in the actual Work site are equivalent and may be used interchangeably: "earth" and "ground"; "earthing" and "grounding". Besides, this article tries to rectify misinterpretation of some important terms often used by people involved in the electrical earthing / grounding work.

Automatic Transfer Switch (ATS) OR Automatic Mains Failure (AMF) Panel

Reliable electrical power becomes one of the most wanted factor in modern world industry where operation should be uninterruptible and maximize the cycle of operation, output quality and to avoid losses and damages. Here we are talking about Automatic Transfer Switches (ATS) also known as Automatic Mains Failure (AMF) panel to cater uninterrupted power supply from Mains or backup sources like Diesel gen-set, static ups etc.

What is Automatic Transfer Switch (ATS)?

Automatic Transfer Switch (ATS) is an automated switching device that transfers load power to backup power during mains failure and back to its original state when mains power reinstate to the normal condition. It will have its own contacts, microprocessor to analyses the conditions whether power supply is normal or backup and need backup or mains power. Here "back up power" may become either Standby generator or another mains power or static power source like UPS.

 

Electrical Earthing or Grounding Method for Road Lighting

A. Earthing Cables: Separate protective earthing cables for lighting column circuits are to be run with power circuit, terminated at LV supply position in lighting control panel and looped into column earthing terminals. The last column is to be bonded via an earthing bolt to a single 16 mm diameter stainless steel rod, 3.6 m long, driven into ground adjacent to column. Bonding is to be 16 mm2 stranded bare copper conductor.

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.

Conduit Wiring In Electrical Construction Contract Works

Scope of Work of this this sample specification covers the supply, installation, testing and commissioning of all wiring materials for power and lighting in concealed and/or surface conduits.

1. Applicable Standards

The conduits shall conform to IS 9537 I & II  or equivalent standards. Switches, Plug Sockets shall conform to IS 3854 and IS 4615, however, contractor shall comply with the latest or superseded versions of IS/BIS to be used for the complete work.

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.

Lighting Distribution Boards (LDB) In Electrical Construction Works

Lighting Distribution Boards (LDB) are an integral and essential part of every building project and it must be designed, manufactured and installed all in accordance with the safety standards. In most of the cases it operates a layman wherein others operate dedicated or trained person. This article explains what are the essential standards, parts, frame to be applied for manufacturing and installation of lighting distribution boards in a quality building project.

Construction Shop Drawings

Construction Shop drawings are the actual detail of all manufactured or fabricated items, indicate proper relation to adjoining work, amplify design details of equipment in proper relation to physical spaces in the structure, and incorporate minor changes of design or construction to suit actual conditions.

Mechanical Services In MEP Construction

Particular Specification For Mechanical Services describes various general requirements In MEP Construction Work, a contractor to follow when they start executing but not limited to unforeseen work or requirements to accomplish the whole project contract.

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.

Engineering Drawing / Drafting

Drawing means lines, shapes, finishes, sizes and colour combined to construct objects or structures. It will be a cumbersome task when narrating an idea without drawing, if the idea is an object or structure. Engineering is heavily depending on drawings, since, technical drawing has developed a global language named Engineering Drawing, capable to express its objects and structure to everyone without the barrier of human languages. Engineering Drawings conveniently helps to explain and record an idea that can be smoothly conveyed to one person to other or sometimes to machine too.