Electrical Systems for the Oil & Gas Industry Rev2

Power Systems Design for the Oil & Gas Industry

IntroPower Systems in Industrial FacilitiesThe role of the Power Systems design engineerApproaching the design processGreenfield BrownfieldDeveloping the load listContinuousIntermittentStand-ByThe Distribution SystemDeveloping/Updating the One-lineCircuit arrangement selectionEquipment SelectionsGeneratorsTransformersCables & Cable SupportSwitchgear SystemsElectric MotorsLighting SystemsPerformer System StudiesHand CalculationSoftware ToolsSelecting Protective DevicesGrounding SystemsHazardous AreasStand-by Power Systems

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Key Study Modules

Course Objectives

Content development guideline

Assumptions

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com INTRO

Power Generation and distribution systems are a critical part of many petrochemical facilities worldwide

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Power Systems in Industrial Facilities

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Power Systems in Industrial FacilitiesThe primary objective of any industrial plant is to produceconsistently and economically. The ability to produce is dependent to a large degree on the adequacyand continuity of the electrical service. In many cases, the cost of service interruptions can be evaluated directly in terms of lost production. This cost may exceed the cost of the physical damage to the electric equipment that caused the interruption.Therefore, it is of prime importance that the electrical system be designed to serve continuously, reliably, and hopefully unnoticed. Since no two plants have identical requirements, a standard electrical distribution system is not universally applicable. Therefore, it is essential to analyze the specific requirements of each processsystem and then design an electrical system which will most adequately meet theserequirements.

Power Systems are typically designed to provide reliable and sufficient electric power to an array of equipment and infrastructure hence the capacity, arrangement and operation of the power systems is dictated by the peculiar requirements of each plant facility

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Power Systems in Industrial Facilities

G

G

C/O SW

33kv

0.415kv

Fused SW

From Base Power House

To CampHouse Power House

1000kva

1000kva

AT AF

Moriah

Faith Academy

Faith Tabernacle

Street Lights

C/O SW

G

1000kva

C/O SW

450kva

Fig. 8 Shiloh Power House

In its simplest form a power generation & distribution system would comprise of some form of electric power generator or incoming utility feeder, distributive switch-gear, cables & and equipment terminating panels

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Power Systems in Industrial FacilitiesPower CablesPower Cables

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com

A One-line representation of More Complex Systems

Power Systems in Industrial Facilities

After Due consideration of peculiar project requirements and constraints the PSE is required to design a reliable, cost effective and constructible power generation and distribution systems.

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com The role of the Power Systems design engineer

Bio-Slide: Shola Daley 44B Ajanaku Str Opebi, Lagos www.IPgruppEngineering.com 018984028 08023036794 Electrical/Electronics OAU 89 Shell Petroleum Warri E/I Engineer(Field) 90-92 Chevron Oil Escravos Facilities Engineer 92-95 Mobil Producing Qua Iboe Terminal Electrical Eng 95-96 Data Communications & Control SouthBank UK 96 Sandersons Construction Company , UK 97-99 Atlas Oil Company Consultant 2000-01 Amazon Energy Limited 2001-03 Ipgrupp Engineering Technical Director 2003-

Basic Design Considerations

SafetyReliabilityMaintenanceFlexibilitySimplicity of OperationVoltage RegulationCost

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Approaching the design process

One of the earliest tasks for the engineer who is designing a power system is to estimate the normal operating plant load. He is also interested in knowing how much additional margin he should include in the final design. There are no hard and fast rules for estimating loads, and various basic questions need to be answered at the beginning of a project, for example;

Is the plant a new, green field plant? How long will the plant exist e.g. 10, 20, 30 years? Is the plant old and being extended? (Brownfield) Is the power to be generated on site, or drawn from an external utility, or a combination of both? Does the owner have a particular philosophy regarding the sparing of equipment? Are there any operational or maintenance difficulties to be considered? Is the power factor important with regard to importing power from an external source? If a generator suddenly shuts down, will this cause a major interruption to the plant production? Are there any problems with high fault levels?

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Approaching the design process

Load Summary

A load summary is a detailed listing of all loads to be served by the electrical distribution system. It is used to determine the power requirements of a systemin order to properly size power sources, distribution equipment, and feeder systems. The load summary also aids in determining system voltages

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Developing The Load List Summary

Load Summary

To develop a load summary, data on all loads to be served and information about the facility processes should be collected first. Generally, industrial facility loads are a function of the process equipment. A list of loads must be obtained from the process and equipment designers. The list should include nameplate ratings of motors, brake-horsepower of electric motor-driven equipment, and kVA and kW ratings of all other process equipment.

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Developing The Load List

Running Load

The actual electrical load of the facility during operation. Running load is used to size utility service, generators, transformers, feeders, motor control centers, circuit breakers, and uninterruptible power supplies. To determine running load, individual loads must be identified as either continuous, intermittent, or spare. Running load is the sum of all continuous loads, including planned future continuous loads. Intermittent loads are included on a percentage basis; spare loads are not included in running load calculation.


Continuous load : Defined as a load that is expected to operate continuously for 3 hours or more.

Intermittent loads: are loads that operate continuously for periods of less than 3 hours.

Spare loads: are operated only when other loads are not operating.


Peak load, the maximum instantaneous load drawn by a system during a statedperiod of time, is obtained when the facility is operating at full capacity and themaximum instantaneous intermittent load is energized. All intermittent loads on asystem normally will not be energized at the same time. Therefore, to estimate peakload the process must be evaluated to determine when the maximum intermittentload will be energized. Peak load is the sum of the running load and the maximuminstantaneous intermittent load.


Stand-by loads should be identified on the load summary to enable the electricalsystem designer to design the stand-by power system. Typically, stand-by loadsinclude critical loads that cause damage to the process or product if power is interrupted,loads required for black start-up of a generator (e.g., jacket water heaters andpumps), selected plant lighting and HVAC loads, and sewage pumps.

Emergency loads deemed essential for personnel safety (e.g., building egresslighting) and UPS loads that require clean uninterrupted power (e.g., computers andcertain electronic instrumentation) should also be identified on the load summary.Typically, emergency loads are powered from unit equipment separate from thestand-by system because of the more stringent requirements of emergency systems.Refer to Sections 124 and 1300 for more information on stand-by, emergency, andUPS power systems.As the design evolves, load estimates should be updated constantly. It is importantto coordinate with other design disciplines to ensure that up-to-date data are used.


Selecting a Power Distribution Arrangement Scheme

Once the load layout has been developed and areas of high load concentrations havebeen identified, a power distribution scheme can be selected. A system should beselected that will distribute power to the load centers by the most economical andreliable means possible that meets the particular facility requirements.The primary distribution voltage can be distributed to the load centers economicallyand reliably with the following systems:

Radial Primary selective Primary loop Secondary selective

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com The Distribution System

Radial SystemIn the radial system, one primary service feeder supplies power from a distributiontransformer to the loads (at utilization voltage) from a load center.This system is simple in operation, and expansion is accomplished easily. A disadvantageof the radial system is that a loss of the source or primary feeder will shutdown all loads connected to that load center. Also, loads must be shut down forsystem maintenance and servicing. The radial system is satisfactory only for installationswhere the process allows sufficient down-time for adequate maintenance.Figure 100-5 is an example of a radial system.

Figure 4 - Simple Radial System Example (IEEE Std.141-1993 Figure 2-1)

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com The Distribution SystemRadial SystemIn the radial system, one primary service feeder supplies power from a distributiontransformer to the loads (at utilization voltage) from a load center.This system is simple in operation, and expansion is accomplished easily.



Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com The Distribution SystemPrimary Selective Distribution - A distribution system philosophy where equipment such as Ring Main Units (RMU's), Switchgear, Load / Motor Control Center, and/or Transformers are connected to two separate primary feeders through switching equipment to provide a normal and an alternate source. Upon failure of the normal source, the equipment can be switched to the alternate source.

Figure - Primary Selective System Example (IEEE Std. 141-1993 Figure 2-2)



Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com The Distribution SystemPrimary Open Loop Distribution - A distribution system philosophy where equipment such as Ring Main Units (RMU's), Switchgear, Load / Motor Control Center, and/or Transformers are connected through a number of tie circuits forming a loop. In this configuration there are two routes which any point on a loop feeder can receive power. The loop is considered "Open" when one of the series switches is open. See Figure 3.

Secondary Selective System

If two unit substations are connected through a normally open secondary tie circuitbreaker, the result is a secondary selective system.

If the primary feeder or a transformerfails, the main secondary circuit breaker on the affected transformer isopened and the tie circuit breaker closed. Operation may be manual or automatic.Maintenance of primary feeders, transformers, and main secondary circuit breakersis possible with only momentary power interruption (or no interruption if thestations can be operated in parallel during switching). Complete station maintenancewill require a shut down. With the loss of a primary circuit or transformer, thetotal substation load can be supplied by one transformer. To allow for this condition,one or a combination of the following features should be considered.


Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Selecting The System VoltageDistribution Voltage

In most facilities it is necessary to distribute power at a voltage higher than the utilization voltages. When choosing a distribution voltage, the first voltage level to consider should be the incoming utility (or generator) voltage. If the utility supplies a voltage in the range of 12,000 volts to 15,000 volts, it is often economical to use this voltage as the primary distribution voltage for the facility becausestep down transformers are not required.

G

G

C/O SW

11,000V

400V

Fused SW

11KV Utility Incomer

High Voltage Power Distribution Network

400V

400V

AT AF

M

Feeders

C/O SW

X

Power Systems Prime power generation in remote Oil & Gas facilities are normally provided using Diesel or Gas fuelled reciprocating engine generator packages or gas turbine generators. For an individual generator that is rated above 1000 kW, and is to be used in the oil industry, it is usual practice to use a gas turbine as the driving machine (also called the prime mover). Below 1000 kW a diesel engine is normally preferred, usually because it is an emergency generator running on diesel oil fuel.

On Many offshore smaller facilities it is also common to see gas fuelled reciprocating engine prime mover for power demands below 1000MW

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Equipment Selection Gas Turbine Generators Diesel Generators Equipment Sizing & Selection

The Gas Turbine Generator

Prime power generation in remote Oil & Gas facilities are normally provided using Diesel or Gas fuelled reciprocating engine generator packages or gas turbine generators.

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Equipment Selection Gas Turbine Generators Diesel Generators Equipment Sizing & Selection


Gas turbines can be classified in several ways, common forms are:-

Aero-derivative gas turbines.

available in single unit form for power outputs from about8 MW up to about 25 MW. These outputs fall conveniently into the typical power outputs required in the oil and gas production industry, such as those on offshore platforms.

Light industrial gas turbines.

Easier maintenance is achieved by designing the combustion chambers, the gas generator and compressor turbine section to be easily removable as a single modular type of unit. The ratings of machines in this category are limited to about 10 MW.

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Equipment Selection Equipment Sizing & Selection


Heavy Industrial gas turbines.

Heavy industrial gas turbines are usually to be found in refineries, chemical plants and power utilities. They are chosen mainly because of their long and reliable running times between major maintenance overhauls. They are also capable of burning most types of liquid and gaseous fuel, even the heavier crude oils. They also tend to tolerate a higher level of impurities in the fuels. Heavy industrial machines are unsuitable for offshore applications because:-


.


Selecting the Generator

What needs to be considered in selecting the generator:-

Location: onshore/offshore

Source of Fuel.

Power Demand

Maintenance

Cost



Step 1. Determine the generator power requirements, Pg (in kilowatts). It is recommended that Pg for primary power generators equal running load plus known future running load plus 10 to 20% spare capacity. For stand-by and emergency generators, it is recommended that Pg equal total connected load plus known future connected load plus 10 to 20% spare capacity.

Step 2. Select a standard generator rating (PG) equal to or greater than Pg. It is recommended that the generator rating be based on a NEMA Class B temperature rise. The generator should be specified with NEMA Class F (or Class H) insulation so that it will operate below its insulation temperature rating during normal operating conditions. This design reduces the stress on the insulation and increases generator life. The generator will also be able to operate in overload conditions for short periods of time and still remain below the allowable temperature ratings.

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Equipment Sizing & Selection


Step 3. Determine the generator voltage drop during starting of the largest motor. Usually a 15 to 20% voltage drop is acceptable if the motor is not started often. The designer should refer to the generator manufacturers motor starting applications data. As a rule of thumb, if thegenerator rating (in kW) is at least five times the numerical value ofthe horsepower of the largest motor, the voltage drop will not begreater than 15% with the generator already loaded to 50 to 75%.


Selecting the Switchgear Assembly

What needs to be considered in selecting the generator:-

Location: onshore/offshore

Source of Fuel.

Power Demand

Maintenance

Cost


ContentsEquipment SelectionsGeneratorsTransformersCables & Cable SupportSwitchgear SystemsElectric MotorsLighting Systems


ContentsEquipment SelectionsGeneratorsTransformersCables & Cable SupportSwitchgear SystemsElectric MotorsLighting Systems

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Developing The Key One-Line Diagram

ContentsOverall One-LineDiagram

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Developing The Key One-Line Diagram

Contents

Perform System StudiesHand CalculationSoftware Tools

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Performing Systems Studies

Contents

Selecting Protective DevicesGrounding SystemsHazardous AreasStand-by Power Systems

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Selecting Protective Devices

Contents

Grounding SystemsHazardous AreasStand-by Power Systems

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Grounding Systems

Contents

Hazardous Areas

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Hazardous Location

Contents

Stand-by Power Systems

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Stand-By Power Systems

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Electrical Design Process Summary Overview

End Multidisciplinary Feasibility Studies

Conceptual Engineering Design Phase

Front End Engineering Design Phase

Detailed Engineering Design Phase

Long Lead Item Procurement

Installation/Construction Phase

Testing/Commissioning Phase

Operation/Maintenance

Procurement

Documentation

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Electrical Design Process Phase Deliverables

Detailed Engineering

Conceptual & Data Gathering

FEED

Develop Basic One-Line Diagram

Conduct Preliminary System Studies

Area Classification Drawings

Updated Key One-line Diagram, Preliminary Equipment Layout Drawings

Further Equipment Specification Documents

Plant Layout

Preliminary System Studies Report

UtilityRequirements

Electrical Load List & Preliminary Equipment Description Document

Process Requirements

Power Supply & Distribution Requirement SpecificationPower Distribution and Operating Philosophy Documents

Equipment Selection and Load Schedules Development

Further System Studies

System Protection Schemes

Update Overall One-Line Diagram

Switchgear/MCC One-line Drawings

Updated One-Line Drawings Incl Load Schedules

Updated Equipment Specification/Layout Documents

Systems Studies Report

Updated One-Line Drawings Incl Load Schedules

Updated Equipment Specification/Layout Documents

Systems Studies Report

Detailed Equipment Layout & Installation Drawings

Detailed Equipment Plans & Elevation Drawings

Complete One-Line Drawings Incl Load Schedules

Complete Equipment Datasheets and PO

Detailed Data Sheets and Bill of Materials

Construction One-Line Drawings

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Adhering strictly to applicable International design codes and regulations help to reduce the risk of this hazard

Risk/Effects of Shock

The effects depend on the current (not the voltage), and the worst damage occurs along its path from the entry to the exit point. Causes of immediate death are ventricular fibrillation and paralysis of the brain's breathing centre or of the heart

Hazards of Electricity

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Typical Body response to Current

Current level(in milliamperes)

Probable effect on human body

1 mA

Perception level. Slight tingling sensation. Still dangerous under certain conditions.

5 mA

Slight shock felt; not painful but disturbing. Average individual can let go. However, strong involuntary reactions to shocks in this range may lead to injuries.

6-30 mA

Painful shock, muscular control is lost. This is called the freezing current or "let-go" range.

50-150 mA

Extreme pain, respiratory arrest, severe muscular contractions. Individual cannot let go. Death is possible.

1000-4300 mA

Ventricular fibrillation (the rhythmic pumping action of the heart ceases.) Muscular contraction and nerve damage occur. Death is most likely.

10,000 mA

Cardiac arrest, severe burns and probable death.

Wet conditions are common during low-voltage electrocutions. Under dry conditions, human skin is very resistant. Wet skin dramatically drops the body's resistance.

Dry Conditions: Current = Volts/Ohms = 120/100,000 = 1mAa barely perceptible level of current

Wet conditions: Current = Volts/Ohms = 120/1,000 = 120mAsufficient current to cause ventricular fibrillation

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Arc FlashCurrent flowing through the air

Produces temperatures above 35,000 degrees F

Statistics show upwards of 2000 persons a year suffer mild to serious injury from this hazard

IT Can Kill You!!

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Electrical HazardsAdhering strictly to applicable International design codes and regulations help to reduce the risk of this hazard

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Major Standards Used for Power System DesignOSHA Occupational Safety and Health Administration

NFPA 70-2005 NEC

NFPA 70E Electrical Safety in the Workplace

IEEE Recommended Practices

IEC International Electro-Technical Commission

BS British Standards

U.L. Underwriters Laboratories

ANSI American National Standards Institute

Client Preferred Design Instruction Guides

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com NFPA 70 - NECThe National Electric Code was first established in1897 Sponsored by the NFPA

Primary design codes for domestic and commercial electrical installations in North America

Not a Design Standard but a minimum Code requirement for safe electrical designs

Provides for several exemptions from Code

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com ANSIThe American National Standards Institute established in 1918 ANSI coordinates and endorses standards produced by accredited standards developers

Created to avoid duplication of standards developed from IEEE, ASME, ASTM and many others

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com IECEstablished In 1906 through leading scientists and pioneering industrialists from around the globe.

Ensures global standardization of electrical apparatus and machinery.

The (IEC 60364) document provides guidance to an authority on developing national wiring principles that would, in turn, serve as the basis to further develop practices & Codes.

Predominantly used Electrical standards in Europe

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com The Institute of Electrical and Electronic Engineers(IEEE)Publishes Technical Standards.The colored books

Categorized into 13 colored books

Blue Book is IEEE Std 1015-2006Bronze Book is IEEE Std 739-1995Brown Book is IEEE Std 399-1997Buff Book is IEEE Std 242-2001 Emerald Book is IEEE Std 1100-2005Gold Book is IEEE Std 493-2007Gray Book is IEEE Std 241-1990 Green Book is IEEE Std 142-2007 Orange Book is IEEE Std 446-1995 Red Book is IEEE Std 141-1993 White Book is IEEE Std 602-2007 Violet Book is IEEE Std 551-2006Yellow Book is IEEE Std 902-1998

www.IEEE.org

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com General Design ConsiderationsCoordination with other engineering disciplines( Process,Piping, Structural)

Plant Operating Considerations ( Onshore/Offshore?-Remote-Plant?)

Green Field/Brown Field Facility??

Plant Maintenance Considerations( Accessibility, By-Pass & redundancy)

Economic Considerations (Cost of Equipment Failure/ Start-Up Cost??)

Electrical Load List Development

Power Supply and Distribution Selection

One-Line Diagram Development

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Key Study Modules Chapter 2

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Electrical Load-List Development

Process Requirements

Utility Requirements

Electrical Code/Safety SpecificRequirements

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Electrical Load-List Development

Electrical Load-List Development P & ID

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Electrical Load-List DevelopmentRule Of Thumb: Matching Load HP to Motor Hp

Driven machinepower rating (kW)Up to 1516 to 55 56 and aboveMargin of motor rating abovethe machine rating multiplier1.251.151.10Select 60HP(45KW) motor as your load

HP =

KW

0.746

= 50.2

37.251

0.746

HP =

= 57.73

50.2 x 1.15

HP =

Motor

Plot Plan

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Electrical Load-List DevelopmentSelect for Arial Lighting

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Power Supply & Distribution Selection

Power Distribution Types

Voltage Selection

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Power Supply & Distribution Specification

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Radial Distribution Systems

G

M

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Primary Selective Distribution Systems

Primary Substation

G

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Secondary Selective Distribution Systems

G

M

M

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Network Distribution Systems

Loads

Loads

G

G

G

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Voltage SelectionUsually 480Y/277 or 415Y/240 depending on National preference

Industrial loads normally supplied through 3phase 480/415V

Lighting and low demand domestic loads would be supplied through the Phase to- Neutral Single phase System 277/240Further Voltage reduction to 208Y/120V is also employed in some Countries to supply Light/domestic loads

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Voltage SelectionUsually 4,160Y/2,400V, 11,000Y/6351V 13,200/7620V

Used when the load center becomes too great or of significant distance from source of power

11,000V/4,160V are the preferred generating voltages for land based facilities in the Oil industry.

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Develop Preliminary One-Line Diagram

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com One-Line Diagram DevelopmentGraphic representation of all the loads, their supply feeder cables, the protective devices on the feeders and termination switchgear equipment

The preliminary load list is a key input document required to develop single line diagrams along with derived feeder circuit protective devices.

One drawing can typically be produced to depict just a few devices in simple load to feeder representation or up to hundreds of devices as required to capture whole sections of the distribution network.

Requires the engineers to have good knowledge of standards graphical symbols used to represent power circuit components

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com One-Line Diagram DevelopmentTypical Graphical Symbols employed

Naturally the preliminary load list is a key input document required to develop single line diagrams along with derived feeder circuit protective devices.

One drawing can typically be produced to depict just a few devices in simple load to feeder representation or up to hundreds of devices as required to capture whole sections of the distribution network.

Requires the engineers to have good knowledge of standards graphical symbols used to represent power circuit components

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Develop Preliminary Single Line Diagram

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Key Study Modules Chapter 3Equipment Selection, Sizing and Specification

Motor

Feeder Cables

Transformers

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Equipment Sizing/Selection

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com The majority of the electrical loads within the process areas of a Oil & Gas plant are motors.

Correct sizing of these equipment to match the load is essential stage of the electrical design.

Recall earlier example of fire water pump

HP =

KW

0.746

Electrical Load-List Development

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com

Rule Of Thumb: Matching Load HP to Motor Hp

Driven machinepower rating (kW)Up to 1516 to 55 56 and above

Margin of motor rating abovethe machine rating multiplier1.251.151.10

Select 60HP(45KW) motor as your load

HP =

KW

0.746

= 50.2

37.251

0.746

HP =

= 57.73

50.2 x 1.15

HP =

Motor

From the pump calculation sheet we can determine the actual HP of motor required to drive the load in this case we would select a 60HP motor

It Is very important to you see the load list development as an iterative process as more information becomes available you go back to update the list

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Several other factors, Standards and electrical Code requirements need to be taken into consideration prior to selecting the motor for your application

Article 430.4 Part winding MotorsArticle 430.7 Markings on Motors

HP =

KW

0.746

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Key Study Modules Chapter 4 System Studies

Short Circuit Analysis

Load Flow & Voltage Drop

Protective Relay Coordination

Harmonic Analysis

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com System Studies

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Arc Flash

General InformationThis training guide was developed by Ipgrupp Engineering. Information contained in this guide is subject to change without notice and Ipgrupp Engineering assumes no responsibility for any damages resulting from use of the information contained herein.

The Information contained in this training guide is protected under the Federal Republic of Nigeria copyright laws and may not be reproduced in whole or in part without written consent by Ipgrupp Engineering

The class participant, by accepting this manual, agrees to the conditions listed on this pageDesign Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com

Design Guide 1 - Key Study Modules Ipgrupp Engineering www.Ipgrupp.com Design of Electrical Systems For the Oil & Gas Industry

*The primary requirement of an Electrical Design Engineer is to provide safe, constructible , reliable and functional power systems to the client

Electrical Systems Design as in most Engineering is pretty much of an art form based on science, suffice to say that it is not an exact science and almost every engineer will approach his tasks slightly differently , however over the years and with the benefit of thousand of both successful and failed projects generally accepted guides, standards, codes and specifications have emerged within the profession to support the engineer in designing safe, reliable, operable and functional power systems. The emphasis in this workshop will be on practical steps , procedures and guides for assisting the engineer to produce required project deliverables typical of multidiscipline projects. It is assumed that participants are quite familiar with basic electrical engineering concepts and our focus will instead be on processes and value tips to complete project specific task.

***Overview of classification of Petrochemical Plants and facilities

*Overview of classification of Petrochemical Plants and facilities




*List Typical Project deliverables

*****For large facilities, a load layout should be created using the plot plan to showmajor load components. If available, individual horsepower ratings should beobtained. Loads located on the plan give a geographical view of the load density,which can be used to assist in devising a logical power distribution scheme. Familiaritywith existing facilities is also helpful.A load center is defined as an assembly (lineup) of low-voltage (0-1000 volts) ormedium voltage (1001-100,000 volts) switchgear. Load center breakers typicallyfeed large motors, motor control centers, or other load centers.Areas containing high load densities should be identified as possibly requiring loadcenters. The load layout should then be used to assist in selecting the power distributionscheme. Section 122 discusses selection of the various types of distributionsystems.Once the basic system has been selected, the load layout is used to assign loads toindividual load centers and motor control centers (MCCs). Loads should beassigned to busses before beginning the load summary so that individual summariescan be made for each bus, making it easier to size system components.A low voltage motor control center (MCC) is a group of motor starters and thermalmagnetic circuit breakers rated up to 600 volts. Typically, 460 volt motors rated 200hp or less are fed from MCCs and started with combination motor starters. Larger460 volt motors commonly are started with circuit breakers if they draw too muchcurrent for combination motor starters. A combination motor starter consists of acircuit breaker, a contactor, and an overload relay. Other loads (e.g., lighting andheating) are served by thermal magnetic circuit breakers in the motor control center.See Section 400, Motor Control Centers.A medium voltage MCC is a lineup of motor starters rated up to 7200 volts. Starterstypically employ a current limiting fuse, a draw-out air or vacuum contactor, andambient compensated overload relays.

*If available, design operating loads should be included.It is important that the system electrical designer acquire knowledge of the facilityprocesses. This knowledge will assist in estimating loads and selecting the propersystem and components.At the initial stages of design, accurate load data may be limited. Loads must beestimated until the design is finalized. It is better to estimate loads on the highside to avoid undersized equipment.

**Power factor and efficiency must be known to calculate the running load. Powerfactor is defined as the ratio of real power (kW) to apparent power (kVA). A loadwith a low power factor (e.g., a motor) draws more current than a load with a higherpower factor. Efficiency is defined as the ratio of output power to input power.Initially, only estimated horsepower ratings may be available, and power factor andefficiency must be estimated. When power factor and efficiency are not known,consider 1 hp of load to require 1 kVA of power. As actual power factors and efficienciesbecome available, particularly for large motors, the load summary shouldbe updated.Two factors used to calculate the running load of motors for the sizing of transformersare demand factor and run factor. Demand factor is the ratio of actualoperating load to nameplate rating. Run factor is the percentage of hours operatingper day, expressed as a decimal equivalent. These factors generally are not used inthe load summary. However, in cases where many large intermittent motors areconnected to a bus, run factors and demand factors should be included in therunning load calculations for economic reasons.

*Power factor and efficiency must be known to calculate the running load. Powerfactor is defined as the ratio of real power (kW) to apparent power (kVA). A loadwith a low power factor (e.g., a motor) draws more current than a load with a higherpower factor. Efficiency is defined as the ratio of output power to input power.Initially, only estimated horsepower ratings may be available, and power factor andefficiency must be estimated. When power factor and efficiency are not known,consider 1 hp of load to require 1 kVA of power. As actual power factors and efficienciesbecome available, particularly for large motors, the load summary shouldbe updated.Two factors used to calculate the running load of motors for the sizing of transformersare demand factor and run factor. Demand factor is the ratio of actualoperating load to nameplate rating. Run factor is the percentage of hours operatingper day, expressed as a decimal equivalent. These factors generally are not used inthe load summary. However, in cases where many large intermittent motors areconnected to a bus, run factors and demand factors should be included in therunning load calculations for economic reasons.



*COORDINATION WITH OTHER DISCIPLINESAt the earliest practical time in a project the engineers will need to identify areas of engineeringand design where interfaces are necessary. An efficient system of communication and exchange ofinformation should be established and implemented at regular intervals. Meetings should be arrangedto discuss problem areas and short-falls in information. The following generally summarises what isneeded, particularly during the feasibility and conceptual stage of a project.In order to be able to engineer an economical and efficient power system it is desirable forthe electrical engineer to have: A basic understanding of the hydrocarbon and chemical processes and their supporting utilitiese.g. compression, pumping, control and operation, cooling arrangements. A procedure for regular communication with engineers of other disciplines, e.g. instrument, process,mechanical, safety, telecommunications, facilities, operations and maintenance. An appreciation of the technical and economical benefits and shortcomings of the various electricalengineering options that may be available for a particular project. The technical flexibility to enable the final design to be kept simple, easy to operate and easyto maintain.1.8.1 Process EngineersThe process engineers should be able to inform the electrical engineers on matters relating to theproduction processes and supporting utilities e.g.: Oil, gas, condensate and product compositions and rates, and their method of delivery to and froma plant. Variation of production rates with time over the anticipated lifetime of the plant.Fuel availability, rates and calorific values, pollution components e.g. sulphur, carbon dioxide,alkali contaminants, particle size and filtration. Electrical heating and refrigeration loads, trace heating of vessels and piping. Make available process flow diagrams, process and instrumentation diagrams, utilities and instrumentationdiagrams.1.8.2 Mechanical EngineersThe mechanical engineers will normally need to advise on power consumption data for rotatingmachines, e.g. pumps, compressors, fans, conveyors, and cranes. They will also advise the poweroutput options available for the different types and models of prime movers for generators, e.g. gasturbines, diesel engines, gas engines.In all cases the electrical engineer needs to know the shaft power at the coupling of theelectrical machine. He is then able to calculate or check that the electrical power consumption isappropriate for the rating of the motor, or the power output is adequate for the generator.The mechanical engineer will also advise on the necessary duplication of machinery, e.g.continuous duty, maximum short-time duty, standby duty and out-of-service spare machines. He willalso give some advice on the proposed method of operation and control of rotating machines, andthis may influence the choice of cooling media, construction materials, types of bearings, ductingsystems, sources of fresh air, hazardous area suitability, etc.The electrical engineer should keep in close contact with the progress of machinery selectionduring the early stages of a project up to the procurement stage in particular, so that he is sure theelectrical machines and their associated equipment are correctly specified. Likewise after the purchaseorders are placed he should ensure that he receives all the latest manufacturers data relating to theelectrical aspects, e.g. data sheets, drawings, changes, hazardous area information. See also Chapter 19and Appendix E.1.8.3 Instrument EngineersThe process and instrument engineers will generally develop the operation and control philosophiesfor individual equipments and overall schemes. The electrical engineer should then interface to enablethe following to be understood: Interlocking and controls that affect motor control centres and switchboards, generator controls,control panels, local and remote stations, mimic panels, SCADA, computer networking, displaysin the CCR and other locations. Cabling specifications and requirements, e.g. screening, numbers of cores, materials, earthing,routing, segregation and racking of cables. Power supplies for control systems, AC and DC, UPS requirements, battery systems. Symbolic notation, e.g. tag numbers, equipment names and labels, cable and core numberingsystems.1.8.4 Communication and Safety EngineersThe communication and safety engineers will be able to advise on power supply requirements for: Radar, radio, telecommunications and public address. Aids to navigation, e.g. lamps, beacons, foghorns, sirens; also alarms, lifeboat davits, etc. Emergency routing and exit lighting systems. Supplies for emergency shut-down systems.1.8.5 Facilities and Operations EngineersThese engineers do not normally contribute any power consumption data, but their input to the workof the electrical engineer is to advise on subjects such as equipment layout, access to equipment,maintainability, maintenance lay-down space, emergency exit routing, operational philosophies ofplant and systems, hazardous area classification.

**A disadvantageof the radial system is that a loss of the source or primary feeder will shutdown all loads connected to that load center. Also, loads must be shut down forsystem maintenance and servicing. The radial system is satisfactory only for installationswhere the process allows sufficient down-time for adequate maintenance.

*Protection against the loss of a primary supply can be gained through the use of aprimary selective system. Each unit substation is connected to two separate primarydown all loads connected to that load center. Also, loads must be shut down forfeeders through switching equipment to provide a normal source and an alternatesource. If the normal source fails, the distribution transformer is switched to thealternate source. Switching can be either manual or automatic, but there will be aninterruption of power until the load is transferred to the alternate source.If both sources can be paralleled during switching, some maintenance of the primarycables (and, in certain configurations, switching equipment) may be performedwithout interruption of service. Cost is higher than for a radial system because ofduplication of the primary cable and switchgear. Figure 100-6 is an example of aprimary selective system.

system maintenance and servicing. The radial system is satisfactory only for installationswhere the process allows sufficient down-time for adequate maintenance.

*The primary loop system offers the same basic protection against loss of primarysupply as the primary selective system. A primary cable fault can be isolated bysectionalizingallowing restoration of service. The cost of this system may beslightly less than the primary selective system.The disadvantage of this system is that locating a cable fault in the loop is moredifficult. The method of locating a fault by sectionalizing the loop and reclosingshould not be performed since it is an unsafe practice because several reclosings onthe fault may be required before the fault is located. In addition, a section may beenergized from two directions. For these reasons, the primary loop system is notrecommended for new facilities. Figure 100-7 is an example of a primary loopsystem.Fig. 100-6 Example Depicting Primary Selective System From IEEE Standard 142, 1993, Ch. 2. Used with permission**A variation of the secondary selective system, a distributed secondary selectivesystem, has two substations in different locationsconnected by a tie cable with anormally open circuit breaker provided in each substation. The cost of the additionaltie circuit breaker and the tie cable should be compared to the cost advantageof locating the unit stations nearer the load center.

In locations where interruptions cannot be tolerated, a variation of the secondaryselective system is to provide a normally closed tie breaker, putting the two loadcenters in parallel. However, this method is allowed only if the available shortcircuit does not exceed the ratings of the secondary buses and breakers.Figure 100-8 is an example of a secondary selective system.

*A variation of the secondary selective system, a distributed secondary selectivesystem, has two substations in different locationsconnected by a tie cable with anormally open circuit breaker provided in each substation. The cost of the additionaltie circuit breaker and the tie cable should be compared to the cost advantageof locating the unit stations nearer the load center.

In locations where interruptions cannot be tolerated, a variation of the secondaryselective system is to provide a normally closed tie breaker, putting the two loadcenters in parallel. However, this method is allowed only if the available shortcircuit does not exceed the ratings of the secondary buses and breakers.Figure 100-8 is an example of a secondary selective system.

*The power supply usually affects system reliability more than any other component.Whether power is obtained from a utility company or is generated, it must bereliable. Electrical failures can cause costly production down-time and equipmentdamage, as well as increase the risk of injury to personnel. Voltage dips can also beparticularly troublesome when computers or high intensity discharge (HID) lighting(e.g., mercury vapor and high pressure sodium) are in use. When considering autility as the source of power, it is important to investigate the outage history andthe quality of the power from the utility. By assigning a dollar value to lost processtime due to power interruptions, the degree of reliability required can be determined.If a facility elects to generate power, the quality and reliability of the generatedpower must be considered, as well as economics.Many economic factors must be considered when deciding whether to producepower or to buy it from a local utility. It is important to remember that many operations,notably refinery operations, require dual sources of power. The utility must beable to provide service to the double-ended substations that are common in refineries,and at a competitive cost. The feasibility (primarily from an economic standpoint)for a facility to generate its own electricity should be evaluated. Perhapswaste gases, waste heat, or other fuels are available at the facility to operate a generatingunit; if not, the availability and cost of fuel should be determined. ShouldFig. 100-8 Secondary Selective System From IEEE Standard 142, 1993, Ch. 2. Used withpermission





*****************The flow chart outlines the classic approach to multidiscipline design in todays Oil & Gas industry and as a matter of fact would loosely apply across most industries. Depending on the size and nature of the project some of these phase could be merged or possibly further elaborated to accomplish specific execution strategies.

whether this is a completely new design(green-field) or an upgrade to an existing plant the design process would pass through all these stages

*Understanding, sequencing and prioritizing the required electrical deliverables( what is a deliverable???- souped up word for drawings, documents, services representing the engineering work you have done!!) is key trick of the trade for competent engineer, A clear articulation of what is required when?? and how this fits with the overall engineering will guide

whether this is a completely new design(green-field) or an upgrade to an existing plant the design process would pass through all these stages

*The effects depend on the current (not the voltage), and the worst damage occurs along its path from the entry to the exit point. Causes of immediate death are ventricular fibrillation and paralysis of the brain's breathing centre or of the heart. Cardiopulmonary resuscitation is the best first aid. Though most survivors recover completely, aftereffects may include cataract, angina pectoris, or nervous-system disorders.

effect of the passage of a current of electricity through the body. Fatality may result from shocks of from 1 to 2 amperes and 500 to 1,000 volts. However, the effect of electric shock on the body depends not only on the strength of the current, but on such factors as wetness of the skin, area of contact, duration of contact, constitution of the victim, and whether or not the victim is well grounded. The general range of disturbances include a mild tingling (usually produced by common static electricity), spasm of the muscles, loss of consciousness, and sometimes death. In addition, burns occur where the current enters and leaves the body. A lethal dose of electricity may paralyze the respiratory organs and damage the central nervous system; the immediate cause of death, however, is usually an interruption of heart action. Electroconvulsive therapy is the use of electric shock to treat certain mental illnesses.

Three primary factors affect the severity of the shock a person receives when he or she is a part of an electrical circuit: Amount of current flowing through the body (measured in amperes). Path of the current through the body. Length of time the body is in the circuit. Other factors that may affect the severity of the shock are: The voltage of the current. The presence of moisture in the environment. The phase of the heart cycle when the shock occurs. The general health of the person prior to the shock. Effects can range from a barely perceptible tingle to severe burns and immediate cardiac arrest. Although it is not known the exact injuries that result from any given amperage, the following table demonstrates this general relationship for a 60-cycle, hand-to-foot shock of one second's duration: Note that a difference of less than 100 milliamperes exists between a current that is barely perceptible and one that can kill. Back > High voltage electrical energy greatly reduces the body's resistance by quickly breaking down human skin. Once the skin is punctured, the lowered resistance results in massive current flow. Ohm's law is used to demonstrate the action. At 1,000 volts, Current = Volts/Ohms = 1,000/500 = 2 Amps which can cause cardiac standstill and serious damage to internal organs.

ArcFlash*Wet conditions are common during low-voltage electrocutions. Under dry conditions, human skin is very resistant. Wet skin dramatically drops the body's resistance.

Note that a difference of less than 100 milliamperes exists between a current that is barely perceptible and one that can kill. Back > High voltage electrical energy greatly reduces the body's resistance by quickly breaking down human skin. Once the skin is punctured, the lowered resistance results in massive current flow. Ohm's law is used to demonstrate the action. At 1,000 volts, Current = Volts/Ohms = 1,000/500 = 2 Amps which can cause cardiac standstill and serious damage to internal organs.*Correct equipment selection and specification is critical to minimizing the risk of Arc Flash Incidences, All electrical equipment are rated by manufacturer to pass only certain levels of current either during normal operation or fault design specifications are required to comply with these standards when locating a device within the distribution network*Correct equipment selection and specification is critical to minimizing the risk of Arc Flash Incidences, All electrical equipment are rated by manufacturer to pass only certain levels of current either during normal operation or fault design specifications are required to comply with these standards when locating a device within the distribution network**As we progress to equipment specification the actual application of this code to day to day design activities will be demonstrated**International Electrotechnical Commission*Provides practical guides, standards and tips for the electrical design engineer, categorized into 13 affectionately labeled colored booksOriginated from North America now used internationally

****In developing the preliminary load list we are required to review the process requirements of the plant

Questions like are what Motor Drives are required, What Heater Loads are envisaged, Lighting and Utility Power Outlets.

Its helps to have some understanding of basic regulatory requirements, like minimum lighting levels for specific industrial areas, minimum SSO per sq meter of specific occupancies (office, equipment rooms.)*An early estimation the possible electrical loads within the plant is probably the most pragmatic start-off point for the electrical engineer working the project. At the conceptual stage of the project cycle you would want to get your hands on preliminary Process diagrams (P & ID), Plot Plans and client detailed project requirements( assuming the client know what they want).The Typical Load List would be work in progress up till and possibly slightly into the detailed engineering phase of the project cycleMost multi-disciplined Engineering Projects in the Oil & Gas Industry are process driven which roughly means that the engineering begins and revolves around the process requirements of the plant, Consequentially the Electrical engineer would have a set of Piping and Instrumentation diagrams (P & IDs) from which to we could begin to determine the electrical load requirements of the plants. The slide displayed is a P & ID for the fire water pump system as would be required for a typical production facility from which we determine that two electric and one diesel fire water pump have been proposed. For the Electrical engineer to proceed would now require knowledge of the Motor sizes to add to the load list. *From the pump calculation sheet we can determine the actual HP of motor required to drive the load in this case we would select a 60HP motor

It Is very important to you see the load list development as an iterative process as more information becomes available you go back to update the list

*Another Key Document the of interest to the electrical folks at this stage of the design would be some form of existing or proposed plot plan from which we could begin to determine area lighting requirement, possible major utility load centers such as living quarters, control rooms , office blocks .***Information available on possible size / type loads and existing power supply systems network will significantly inform the type of distribution system specified for your projects

Most common and simplest to design/operate

Low cost

Consist on a main feeder to mains distribution switchboard from which multiple supply feeders take-off to terminal circuits or further secondary distribution boards

The conventional simple-radial system receivespower at the utility supply voltage at asingle substation and steps the voltage downto the utilization level. In those cases wherethe customer receives his supply from theprimary system and owns the primary switchand transformer along with the secondarylow voltage switchboard or switchgear, theequipment may take the form of a separateprimary switch, separate transformer, andseparate low voltage switchgear or switchboard.This equipment may be combined inthe form of an outdoor pad mounted transformerwith internal primary fused switchand secondary main breaker feeding anindoor switchboard.Another alternative would be a secondaryunit substation where the primary fusedswitch, transformer and secondary switchgearor switchboard are designed and installedas a close coupled single assembly.In those cases where the utility owns the primaryequipment and transformer, the supplyto the customer is at the utilization voltage,and the service equipment then becomes alow voltage main distribution switchgear orswitchboard.Low-voltage feeder circuits run from theswitchgear or switchboard assemblies topanelboards that are located closer to theirrespective loadsThe conventional simple-radial system receivespower at the utility supply voltage at asingle substation and steps the voltage downto the utilizatio

Electrical Systems for the Oil & Gas Industry Rev2

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