Two major documents are required for this task.
They are;
- The equipment list
- Motor power user summary.
The equipment list prepared by the mechanical and process combined group is
passed to the electrical group for action. Some equipment may not be indicated
to be either electric or gas driven on the equipment list. Such equipment are
clarified on the P&ID, where detailed information concerning every equipment is
usually provided.
Motor Power User Summary
The motor power user summary is a detailed listing of all electric driven
equipment in the equipment list. Such equipment are compiled on a separate list
termed the Motor power user summary.
Voltage Levels.
After compiling the motor power user summary, the next task is to define the
voltage levels.
All motors might not run on the same voltage. Voltage levels are defined from the
motor power user summary.
A motor power user summary contains the following loads.
500Hp pump
30Hp pump
250Hp pump.
There are 2 optional voltage levels vis 4160V and 480V. What load would be
placed on which voltage level?
The 500Hp and the 250Hp pumps should be placed on 4160V. This is done in
order to avoid very high current which may lead to having very large feeder and
other switchgear accessories to supply the pumps.
By Bechtel standards
0-130kw pumps are placed on Low Voltage
131kw and above are placed on Medium Voltage.
NOTE : This is not fixed for all projects. On EGP3 for example, 150kw pump
were placed on Low Voltage , based on the client standards and requirements.
Load Factor
This is the ratio of the time a load is used for the total time in a day. e.g if a load
is in use for 8hrs in a day the load factor is 8/24 = 1/3
Load factor = Absorbed load.
Nameplate rating
Absorbed load = Load Factor X Nameplate Rating
Absorbed load. = Efficiency
Consumed load
Consumed load = Absorbed load
Consumed load = Load factor X Nameplate Rating
From the above, if the absorbed load is given from the equipment list the
consumed load could be calculated.

The consumed load could also be calculated from the name plate rating of the
motor using the load factor and the efficiency.
When efficiency is not given , a typical manufacturer’s reference could be

ground symbol
However the manufacturer must be clearly stated in the calculation and
a copy of the relevant page should be attached. Consumed load is sometimes
referred to as operating load.

The load summary can now be drawn in tabular form as shown below.


What the
would do.




ground symbol 

ground symbolground symbolground symbolFrom the total on the load list, the overall power factor of the system can be
Correction Factors.
Correction factors applied in summing the total consumed load vary from one
organization to the other.
However for the purpose of the training the following correction factors are
Correction load (C) 100%
Intermittent load (I) 30%
Standby load (S) 0% unless otherwise stated by client e.g. Shell DEP
recommends 10% for standby loads.
From the above factors
Running load = C+ 30%I
Peak load = C + I

Electrical Distribution System.

This is a network showing the flow of power from the source to the load points.

Components of an electrical distribution system include.







Protective devices.

Factors To Consider When Desiging An Electrical Distribution System.

The following points should be considered

- Continuity of supply

- Maintainability

- Flexibility

- Durability

- Cost effectiveness

- Safety

Understanding System Configuration

An electrical distribution system should  be configured in a manner that ensures power supply to load centers economically and reliably.
Types of system configuration include
nPrimary selective
nPrimary loop
nSecondary selective 
Emergency power sources include
nEngine driven generator set
nStorage batteries
nUninterruptible Power sources UPS
nUnit Equipment
Factors to consider when designing emergency power systems
nQuality of power required
nMotor starting requirements
nAnticipated future loads
nTime requirements
nSwitching conditions
Factors to consider in selecting utilization voltages include
nSpecific load server (size and voltage level)
nVoltage level supplied by the utility or on-site generation
nExisting voltage levels in the facility
nCost of electrical equipment and cable at different voltage levels and current ratings
nLosses due to higher current (at lower voltages)
nOverall system flexibility (i.e. capacity for future expansion)

Understanding Process and Load Data

Commercial and Industrial Electrical Systems is a comprehensive coverage on every aspect of design, installation, testing and commissioning of electrical systems for residential, commercial and industrial buildings.

 For a electrical system to perform according to industrial standard the engineers or technician working on the electrical system must understand pertinent aspect of network and installation of electrical system from project procedures, rules and standard to design principle and installation practice. It is therefore imperative that the drafters and designers must consider the process and load data.

§Process and load data are compiled in form of an electrical load summary. The data used in compiling the electrical load summary are extracted from the equipment which is list jointly prepared by the process and mechanical groups, while detailed information on the mode of supply are picked from the  P&ID.
§ Definition – Load Summary
A detailed listing of all load to be served by the electrical distribution system. It is used to determine the power requirements of the system in order to properly size power sources, distribution equipment, and feeder systems. The load summary also aids in determining system voltages.
Components of a Load Summary
Running load
Peak load
Stand-by load
Emergency load
Definition – Running load
The actual electrical load of the facility during operation. Running load is used to size the utility service, generators, transformers, feeders, motor control centers, circuit breakers, and UPS
Components of a Running load
nContinuous load – loads expected to operate without stopping for 3 hours or more
nIntermittent load – loads expected to operate without stopping for periods less than 3 hours or more
nSpare load – loads which operate only when other loads are not operating
Definition - Peak load
The maximum instantaneous load drawn by a system during a specified period of time. It is obtained when the when the facility is operating at full capacity and the maximum instantaneous load is energized. 
 Definition - Stand-by loads
Critical loads that may cause damage to process or product if power is interrupted.
Definition - Emergency loads
Loads deemed essential for personnel safety and UPS loads
Correction Factors
Correction factors applied in summing the total consumed load vary from one organization to the other.
Assume the following for this training only
Continuous load (C)           100%
Intermittent load (I)      30%
Standby load      (S)            0%
 From the above factors
Running load  = C+ 30%I
Peak load       = C + I

Introduction to Electrical Engineering Drafting and Design

Introduction Engineering Drafting & Design For Electrical System Drafters and Designers.

Before we jump into Autocad tutorial we must first of all understand engineering drafting and design concepts. though the purpose of this site is for people that want to major or improve their performance in electrical system design, and instrucment and process design (P&ID). However the overall Autocad tutorial is for all autocad knowldege seekers.But the design principle and theory will be electrical for now.

  What is Drafting and Design Engineering? 
Drafting and Design Engineering is an exciting career that allows the engineer to be involved in all stages of the design process, from conception to presentation of the finished plans. It requires a working knowledge of drafting and design principles, material types and properties, and manufacturing processes.

There are two major stages involved in electrical system design:
 *Conceptual Design
 * Detailed Design 
 Conceptual design stages
 * Process and load data 
* Suitable configuration 
* Power source and System voltages 
Detailed Design stages are: 
* One Line Diagram 
* System Studies 
* Equipment sizing 
* Grounding and lighting systems 
* System protection Jobs of Electrical Drafters and Designers.

 Electrical Drafting and design engineers prepare electrical or digital drawings, diagrams or blueprints and/or models of various electrical systems or structures to guide product makers, architects or construction personnel, and other engineers involve in engineering jobs in the manufacture, implementation or building process. They often use computer-aided drafting (CAD) and/or computer-aided drafting and design (CADD) software, drafting and design engineers provide the vital link between design theory and practical application by translating critical design concepts into workable plans for tangible, buildable electrical and instrument, mechanical and architectural end-products.

 Drafting and design engineers create the designs and sketch out the detailed plans for construction projects such as commercial, industrial, residential building, turbine, and a wide variety of manufactured products (automobiles, airplanes, computers and heating and air conditioning systems, (HVAC), Lighting, loads etc. 

How to Become a Electrical Drafting and Design Engineer  

Candidates for this field can either begin by seeking professional certification as a drafting and design technologist, CAD Operator and later move on to an engineering degree program.
 Jobs Opportunities for Electrical Drafting and Design Engineers. There are many jobs opportunities in manufacturing industries, Airport, Shipping and maritime sectors, and most especially in oil and gas sectors who highly need the services of an electrical Drafters and Designers. Drafters and designer can be self employ and also work as a consultant to engineering firms.







ØSimplicity of operation

ØVoltage regulation