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A day in the life of a Project Engineer

natie — Tue, 27 Oct 2009 15:33:55 +0000

A day in the life of a Project Engineer
My responsibilities as a project engineer changes dynamically between two disciplines during the project life cycle, one of Project Engineering and Project Management .and involves both office and site work activities.
My day as a project engineer changes everyday depending on the project phase since different skills are required and different activities are performed at different stages of the projects.
Project Engineer
A typical day during engineering phases of a project (initial phase and execution phase) involves:
•   Design review meetings with all stakeholders (Client, engineering consultants, draughtsman)
•   Project specifications compliance, design modifications, drawing designs approval procedure with all stakeholders’ involvement.
•   The design implementation process happens during the project execution phase (onsite) and if the approved designs do not work on site the design changes, modifications
•   Consultation with subject expects from different disciplines including, mechanical, civil, metallurgy depending on the project’s scope of work, and our involvement in the design as stipulated in the contract.
Important skills: Paying attention to details, technical astuteness, working with other professionals.
Project Manager:
My project management responsibilities have a longer lifecycle than engineering ones, as they stretch from project initiation to project handover, and they consist of:
•   Contract’s administration which involves full understanding of types of contract strategy and different conditions of contracts (ECC, FIDIC, GCC & JBCC) that one is dealing with at any point especially when handling multiprojects.
•   Procurement of all project’s equipments, material and services, this forms first area of cost management for the project to ensure the profitability of the project.
•   Project scope management, site progress monitoring, reporting and managing. Through daily site work update, routine site visits and site meetings to re emphasize the importance of Safety, Quality and Time management
•   Site teams management and managing project risks throughout the projects to ensure that all clients objectives deliverables are l met in time within budget, and that one’s projects remain profitable

Important skills: General management skills, human relations, communication skills, deligation and time management.

Transmission Lines

natie — Sat, 19 Sep 2009 15:23:08 +0000

Transmission Lines
Transmission lines carry electric energy from one point to another in an electric power system. They can carry alternating current or direct current or a system can be a combination of both. Also, electric current can be carried by either overhead or underground lines. The main characteristics that distinguish transmission lines from distribution lines are that they are operated at relatively high voltages, they transmit large quantities of power and they transmit the power over large distances.

The types of transmission lines are:

Overhead Transmission Lines
Subtransmission Lines
Underground Transmission Lines

Overhead AC Transmission Lines

Overhead AC transmission lines share one characteristic; they carry 3-phase current. The voltages vary according to the particular grid system they belong to. Transmission voltages vary from 69 kv up to 765 kv. The following are examples of different overhead transmission line structures in use today. The DC voltage transmission tower has lines in pairs rather than in threes (for 3-phase current) as in AC voltage lines. One line is the positive current line and the other is the negative current line.

Some typica transmission line structures

Transmission Lines

Woodtower Transmission Lines

Transmission Lines

Subtransmission Lines

Subtransmission lines carry voltages reduced from the major transmission line system. Typically, 34.5 kv to 69 kv, this power is sent to regional distribution substations. Sometimes the subtransmission voltage is tapped along the way for use in industrial or large commercial operations. Some utilities categorize these as transmission lines.

Subtransmission Pole

Description

Wooden Transmission Lines

Underground Transmission Lines

Underground transmission lines are more common in populated areas. They may be buried with no protection, or placed in conduit, trenches, or tunnels.

Transmission lines are installed in a tunnel,which enables many circuits in a limited area.

Overview from Power Plant to Consumer

natie — Sun, 13 Sep 2009 07:37:54 +0000

A typical power generation, transmission and distribution system has these components: Power Generation Plants, Substations, Transmission Line and Distribution systems.

From Power Generation to Consumer

Power Generation Plants

Substations

Step-up Transmission Substation
Step-down Transmission Substation
Distribution Substation
Underground Distribution Substation
Substation Functions
Substation Equipment

Transmission Lines

Overhead Transmission Lines
Subtransmission Lines
Underground Transmission Lines

Distribution Systems

Industrial Customer
Commercial Customer
Residential Customer
Transportation Customer

Underground Distribution Substations

natie — Sun, 13 Sep 2009 07:18:42 +0000

Underground distribution substations are also located near to the end-users. Distribution substation transformers change the subtransmission voltage to lower levels for use by end-users. Typical distribution voltages vary from 19,920 volts to 2400 volts.

Underground Distribution Substation

An underground system may consist of these parts:

Conduits
Duct Runs
Manholes
High-Voltage Underground Cables
Transformer Vault
Riser
Transformers

Conduits:

Duct

Duct 2

Conduits are hollow tubes running from manhole to manhole in an underground transmission or distribution system. They can contain one or more ducts (See Duct Runs). They can be made of plastic (PVC), fibreglass, fibre, tile, concrete, or steel. PVC and fibreglass are most commonly used.

Duct runs:

Duct runs are hollow tubes running from manhole to manhole inside a conduit in an underground system. They are of various sizes usually from 2 to 6 inches in diameter. Electrical cables are run through ducts and the ducts are sized accordingly. The diameter of a duct should be at least 1/2 to 3/4 inch greater than the diameter of the cable(s) installed in the duct. They can be made of plastic (PVC), fibreglass, fibre, tile, concrete, or steel. PVC and fibreglass are most commonly used.

Manhole:

A manhole is the opening in the underground duct system which houses cables splices and which cable men enter to pull in cable and to make splices and tests. Also called a splicing chamber or cable vault.

High-Voltage Underground Cables:

High-Voltage underground cables are constructed in many different ways, but are usually shielded cables. They are made with a conductor, conductor-strand shielding, insulation, semi-conducting insulation shielding, metallic insulation shielding, and a sheath. The sheath can be metallic and may then serve as the metallic insulation shielding and be covered with a nonmetallic jacket to protect the sheath. This sheath helps to reduce or eliminate inductive reactance. Such cables are commonly used in circuits operating at 2400 volts or higher.

High Voltage Cables

High Voltage Cables 2

Transformer Vault:

Underground Transformer Vault

A transformer vault is a structure or room in which power transformers, network protectors, voltage regulators, circuit breakers, meters, etc. are housed.

Riser:

A riser is a set of devices that connects an overhead line to an underground line. A riser has a conduit from the ground up the pole where potheads are used to connect to the overhead lines.

Riser 1

Riser 2

Underground Transformer:

An underground transformer is essentially the same as an aboveground transformer, but is constructed for the particular needs of underground installation. Vault type, pad-mounted, submersible, and direct-buried transformers are used in underground systems. Pad-mounted transformers are installed on a concrete pad on the surface near the end-user.

From here the power is distributed to industrial, commercial, and residential customers.

What is a substation transformer?

natie — Sat, 12 Sep 2009 14:52:07 +0000

It is a large encased group of metal plates about the size of a small house with 2 sets of insulated copper wires wrapped around the plates -an input and output – to convert a very high transmission supply line voltage – maybe 44 thousand volts to a lower voltage of 2200 volts that runs down the power line poles in your neighbourhood. Look at your street’s power poles and you will see a mini substation that converts he 2200 volt to 220 volts and may supply several homes.

to view the rest click on the link on the left :http://wiki.answers.com/Q/What_is_a_substation_transformer

Electric Power Transmission

natie — Sat, 12 Sep 2009 14:48:37 +0000

Electric power transmission: Bulk transfer of electrical energy, a process in the delivery of electricity to consumers.

Power plants are typically connected to multiple substations near a populated area through the power transmission network.

Electricity distribution: the wiring from the substations to the consumers. Historically this business model separates the wholesale electricity transmission business from distributors who deliver the electricity to the consumers (homes). Distant energy sources (such as hydroelectric, coal and nuclear power plants etc) are connected to the consumers in towns and cities through electric power transmission.

Mostly three phase alternating current (AC) is used by transmission lines, however single phase current can be used by the railway in the railway electrification system. For long distance transmission high voltage direct current systems are used. This is also the same for undersea cables, or connecting two different AC networks

To reduce energy loss in transmission electricity is transmitted at high voltages (110kV and above). Because of the lower installation cost and easier maintenance overhead transmission lines are preferred for long transmission lines. Underground power transmission would rather be found in densely populated areas.

A power transmission network is referred to as a “grid”. In order that power can be routed multiple redundant lines between points on the network are provided. Power can so be routed between any power plant to any load centre, through a variety of routes, based on the economics of the transmission path and cost of power. Transmission companies do a lot of analysis to determine the maximum reliable capacity of each line.

Transmission Substation

natie — Fri, 11 Sep 2009 20:00:59 +0000

Transmission substation: Where you connect two or more transmission lines you would use a transmission substation.

In a very basic situation you would have two transmission lines with the same voltage. In such a situation the transmission substation contains high voltage switches that allow lines to be isolated or connected for maintenance or fault clearance.

A transmission substation may have transformers to convert between two or more transmission voltages. It would also have voltage control devices such as capacitors, reactors and equipment such as phase shifting transformers to control power flow between two adjacent power systems.
These transmission substations can range from basic to intricate. A basic “switching station” may be a bit more than an electrical bus (a common electrical connection between multiple electrical devices) plus a few circuit breakers. The biggest transmission substations can cover an extensive area with multiple voltage levels, large amount of circuit breakers, protection and control equipment (voltage and current transformers, relays and SCADA (Supervisory Control And Data Acquisition) systems)

Step-Up Transmission Substation

Step-down transmission Substation

Transmission Line Substation (step-down)

A step-up transmission substation receives electric power from a nearby generating facility and uses a large power transformer to increase the voltage for transmission to distant locations. A transmission bus is used to distribute electric power to one or more transmission lines. There can also be a tap on the incoming power feed from the generation plant to provide electric power to operate equipment in the generation plant.

A substation can have circuit breakers that are used to switch generation and transmission circuits in and out of service as needed or for emergencies requiring shut-down of power to a circuit or redirection of power.

The specific voltages leaving a step-up transmission substation are determined by the customer needs of the utility supplying power and to the requirements of any connections to regional grids. Typical voltages in USA are:

High voltage (HV) ac:    69 kV, 115 kV, 138 kV, 161 kV, 230 kV
Extra-high voltage (EHV) ac:    345 kV, 500 kV, 765 kV
Ultra-high voltage (UHV) ac:    1100 kV, 1500 kV
Direct-current high voltage (dc HV):    ±250 kV, ±400 kV, ±500 kV

Direct current voltage is either positive or negative polarity. A DC line has two conductors, so one would be positive and the other negative.

Step-Down Transmission Substations

Step-Down Transmission Substation

Step Down Transformer

Step-Down transmission substations are located at switching points in an electrical grid. They connect different parts of a grid and are a source for subtransmission lines or distribution lines. The step-down substation can change the transmission voltage to a subtransmission voltage, usually 69 kV. The subtransmission voltage lines can then serve as a source to distribution substations. Sometimes, power is tapped from the subtransmission line for use in an industrial facility along the way. Otherwise, the power goes to a distribution substation.