Internship Report

1Page

Prince Mohammad Bin Fahd Universi t y

C o l l e g e o f E n g i n e e r i n g

Department of Electrical Engineering

Internship Report

at

[Sabic- Sharq]

R e p o r t i n g P e r i o d :

[16/6/2012 – 8/8/2012]

S u b m i t t e d b y :

[ K h a l i d A L - H u s s a i n ]

[ 2 0 0 7 0 0 2 6 3 ]

[ s u b m i s s i o n d a t e ( 1 5 / 9 / 2 0 1 2 ) ]

Electrical Engineering Department

Summer 2012

Internship Report

2Page

Abstract:

The importance of this internship is gaining experience, information, Knowledge and

Practical skills as much as I can for about two months. This report is demonstrating

my efforts in Sharq Company, its department, products, substations, Plants, my plan

for the internship, and the tasks and responsibilities. Further, its applications about

electrical engineering, plants and Substations are good for the engineer to relate the

theory to practical life. The information was from my experience at working in the

company, manuals, reliable books and some assistance from the engineers in Sharq.

The internship period was so beneficial that I covered the majority of the power

system information.

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Table of Content

Introduction: 5

Acknowledgement: 6

Switch Gear: 7

Motor Control center (MCC): 7

Charger: 8

UPS: 8 a. Power Factor Study: 8

b. Load Flow Calculations: 8 c. Short Circuit & Voltage drop: 9

Conditions of calculations: 9

d. Cable Sizing Calculations: 9

Basic Training: 9

Fluorescent lights: 9

Mercury Vapor and Sodium: 11

Single Phase Motor: 11

Gas insulated switch gear (GIS): 11

Generators: 12

Cathodic protection: 12

The Impressive Current method (ICCP): 12

Sacrificial Anodes Cathodic protection: 12

VVVF: 13

Description about the component of VVVF 13

Protection System: 11

Some Protection devices in brief: 11 CT: 11 PT: 11

Differential relay (Relay 87): 11

Example for differential relay: 15 Synchronism Relay (Relay 25): 15

Fuses: 16

The Company: 16

Sharq Safety: 16

Root cause analysis: 17

RCA steps: 17

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Heat Stress Announcements: 17

Conclusion: 21

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Introduction:

During training at Sharq, I was assigned to visit substations and plants in order to

relate whatever in theory to practical life. The nature work of electrical engineering

needs some policies and cautions. Therefore, attending the safety lecture of the

company is for saving yourself and the environment. The importance of this

internship is learning and gaining experience to see how the practical life going about

my field, how to deal with some technical problems, how test emergency machines by

weekly or monthly. Ultimately, the engineer must seek for the information by himself,

so he won't forget it.

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Acknowledgement:

Accomplishing this assignment was a very challenging goal in my life especially

being a first time at a workplace. It could not have been destined to become a reality

without those who have supported me throughout my way, for those I express the

below thanks:

Firstly, my appreciation to Almighty Allah for his endless blessings and for providing

me with health and strength to attain this degree.

Secondly, my utmost gratefulness and love to my mother who never cease or get

bored of blessing me with her prayers, may Allah reward her with the best in this life

and the life thereafter.

Last but not least, the engineers of Sharq company who assisted me a lot. First, my

supervisor Abdullah AL-Baghdadi was assisting me as much as he can, so I can get

benefits. Also, Mr. Pawan helped me in protection system. Sampath, was helping me

to understand the cathodic Protection. Jaber AL-Malki was helping me in

transformers.

.

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Switch Gear:

Switch gear is combination of circuit breakers to feed whatever is needed. It can feed

transformers, substations, plants, etc. (See figure 1). There are three switch gears in

their substations in terms of voltage level in their substations such as Medium Voltage

Switch gear (4.16 KV), low voltage switch gear (480V) and High voltage switch gear

(13.8 KV). Each switch gear has GE Relays such as 750 relay for the feeders, 745 for

the transformers, and the 469 relay for the motors. Also, switch gears has ATS, and

Relay test blocks which used for testing the relays.

Figure 1

(Switch Gear)

Motor Control center (MCC):

It's the same as switch gear, but it has contactors instead of circuit breaker and fuses

for protecting over currents. Of course, the Multilin 469 is a part of it.

Figure 2

(MCC)

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Charger:

a. Description: System which is useful to charge the dc controls during any

interruption. Further, the battery will charge the interrupted dc control switch

for a limited time during its interruption

b. Circuit: There is an input MCCB switch will make the rectifier to convert

from Ac to dc to charge a battery f. If any dc control switch fails, the battery

will feed it.

UPS:

Description: it’s uninterrupted power supply, which mainly used as a backup power

supply. If any interruption of ac equipments, motors, or valves, the UPS can feed

them when they are interrupted.

Circuit: The Rectifier will convert from ac into a dc for the battery, and then inverter

will convert from dc to ac again. If this operation fails, the bypass MCCB will work

by static switch. Then, it will send a signal to transformer and ultimately it will save

our plants from interruption.

Figure 3

(UPS & Charger)

a. Power Factor Study:

If the load is inductive, the capacitor enhances the voltage, reduces the current,

reducing line losses and reducing power bills and thus leading unity power factor.

Capacitor useful as a storage element and if it's a series with an inductor, it will

maintain the voltage.

b. Load Flow Calculations: Load flow calculation is about studying Voltage Profile, Power Flows, Current Flows,

Power Factors, Transformer LTC Settings, Voltage Drops, Generator’s Mvar Demand

(Qmax & Qmin), Total Generation & Power Demand, Steady State Stability Limits,

MW & Mar Losses.

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c. Short Circuit & Voltage drop: Short circuit occurs between two phases or phase ad ground as a result of weak

insulation resistance.

Conditions of calculations:

1. Drawing the equivalent of per unit impedances for each element of the circuit.

2. Impedance of transformers, cables, bus ducts, etc. are required. But the

impedances of transformers, etc. are neglected.

3. Calculating mathematical equations to calculate the percentage drop. And

Ideal Circuit analysis theory for the calculating the short circuit current.

Note: Each of studies has its own calculations, but the most important point is to

convert the actual circuit into per unit and then calculates what is required.

d. Cable Sizing Calculations:

Procedure of calculations:

1. Calculating the continuous current.

2. Calculating the voltage drop across the cable.

3. Calculating the Maximum length of cable.

Basic Training:

I was assigned to attend the basic training course about my field in order to gain my

experience about electrical engineering. There are many information are very

impressive to learn in terms of practical life. This course covered street light and some

kinds of motors.

Fluorescent lights:

There are two types of fluorescent lights. The first is t is preheat type, when the circuit

is energized the current will flow from cathode A and then to cathode b through the

starter. Then, a heat will affect the gas inside the lamp and thus an arc will occur

across the fluorescent lamp. The second is the rapid type; the ballast will deliver a

small voltage to heat the cathodes. There isn't starter needed. Cathodes will heat the

gas, so the gas will be increased and higher current and lower resistance.

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Figure 4

(Preheat Light)

Mercury Vapor and Sodium:

The ballast will deliver a voltage to the electrodes. The starter resistor will control the

current flowing. An arc will be struck between the starting electrode and the two main

electrodes. Therefore, the current will be high and resistance and that makes the

mercury vapor increased. Ultimately, the lamp is working. Sodium vapor doesn't have

the starting resistor and electrodes, but only two main electrodes. However, there is an

igniter that will deliver high voltage and high frequency to the electrodes and heat the

sodium vapor and arc will occur to make the lamp work. (See figure 5 & 6)

(Figure 5)

Mercury Vapor

(Figure 6)

Sodium Vapor

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Single Phase Motor:

The supply voltage will deliver current which will go into two loads. The first load

has Capacitor, Centrifugal switch and starting winding. The second load has running

winding. The current will flow through the capacitor and centrifugal switch and then

starting winding. The starting winding will produce a magnetic field to make the rotor

rotate. When the rotor reaches the required speed, the centrifugal switch will open.

The running winding will make the rotor to continue rotating. The purpose of having

the capacitor in the circuit is maintain the wattage, voltage , and also to make phase

shift between the running period and starting period is 90. (See Figure 7)

(Figure 7)

Single phase motor

Gas insulated switch gear (GIS):

GIS is the upstream of the substations. A gas (SF6) insulated substation may have

underground feed lines and be nearly invisible to the average person. Distribution

circuits supplied by gas insulated substations normally have an alternate feed from

another substation, to allow maintenance work on the gas insulated site. For instance,

Sceco is feeding Voltage to Sabic Company, then GIS will feed transformer to feed

substations. Furthermore, the SF6 circuit breaker is available in the GIS because it's

useful for the high voltage sides. (See figure 8).

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(Figure 8)

GIS in ABB Company

Generators:

There are many sources of generations such as Hydroelectric, nuclear, natural gas,

fossil fuel and diesel engine. Indeed, the generator is converting from mechanical

energy to electrical energy according to the first law of thermodynamic.

Cathodic protection:

Cathodic protection is technique which is useful to protect the buried pipelines, Metal

tank, and reinforced concrete structure from the corrosion. Usually the anode part "the

positive part" is for decaying and the cathode part for protecting the metal product and

that's why it's called Cathodic protection. Two methods are useful in cathodic

protection and these methods are the Impressive current and the sacrificial anode.

The Impressive Current method (ICCP):

The Impressive Current Cathodic Protection systems use anodes connected to a DC

power source. The rectifier bridge is useful to convert from ac source to dc powers

source. At the end of the rectifier bridge, there are two terminals. The positive

terminals for the anode for decaying and the negative terminal are for the cathode for

protection.

Sacrificial Anodes Cathodic protection:

There is something known as Fe and if it's added to a carbon, it will become hard

steel. In addition, the magnesium will be a good solution to avoid the corrosion. The

magnesium can be considered as the anode part for decaying, and the steel can be

considered as the cathode part for protection.

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VVVF:

It’s a Power Electronics device, which generates a variable voltage and variable

frequency output from a fixed input that has constant voltage and frequency. If the

magnitude of maximum variable output voltage equals to the input voltage, the

maximum output frequency is as high as 8 to 10 times the input frequency. It’s crucial

to adjust the speed for some reasons, such as machine or Process Requirements,

Energy Savings, Automated Factory Concept and Productivity Increases. The main

purpose of the VVVF is controlling the speed of the motor.

Description about the component of VVVF

The transformer will step down the voltage to the rectifier. The rectifier is able to

convert from ac to dc signal and also have an output signal without any distortion.

The inverter will convert from dc to ac again. If the VVVF becomes heated from

inside, there are cooling fans able to cool it. The Display is comprised of a graphical

LCD with some tabs for the display that has a various functional data, eight keys,

three LED’s, and encoder. (See the following figures)

Figure 9

Inverter (Convert DC to AC with different frequency)

Figure 10

Control circuit

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Figure 11

Cooling fans

There are two group fans and each group has two fans. Each group is redundant

Protection System:

It's crucial to protect our plants and substations from the damages, Arc hazards, Faulty

currents, over voltages, etc.

Some Protection devices in brief:

CT: The current transformer steps down a current to the relay, so the relay can read it and

will check if any fault occurs, then the breaker will open to clear the fault. (See

Figure12)

Figure 12

(CT)

PT: The voltage transformer will step down a voltage to relay and thus breaker will trip if

any fault occurs.

Differential relay (Relay 87): If there is two current transformers and a transformer between them, and a differential

relay will measure the difference between the primary current and the secondary

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current. If the difference occurs, then the relay will make the breaker to trip. (See

Figure 13).

(See Figure 13)

(Differential Relay)

Example for differential relay:

There are two CT and one transformer between them. The two CT will take the ratio

to Differential relay to see the different current as previously mentioned. If the fault

occurs externally, the relay will not operate, but if it occurs internally the relay will

operate. For higher external fault, the biased differential relay which has two

retraining coils is Ideal solution.

(The one on the left is internal fault and the one on the right is external fault)

Synchronism Relay (Relay 25): This relay is Ideal for the ATS, especially in Substations if there are three breakers.

One in section A, the other in section B and the third is between. If you want to open

one of both manually by using the button, the indication will come from the relay to

demonstrate which Section has a problem. If there isn't any indication, there won't be

damage if you hold the execution button for three seconds.

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Fuses: Fuses are helpful to clear a fault over current in the system. If it fails, the circuit

breaker can clear. (See figure 15)

(Figures 15)

Fuses

The Company:

The best company that produces the petrochemical in the Middle East is SABIC

Company, which is established in 1975 in Jubail industrial city. Furthermore, Sharq

Company is established on May 1981, which is one of SABIC companies. The most

crucial products of Sharq Company are Polyethylene and ethylene glycol. The two

types of poly ethylene are the low density and High density. The department that I

was working at is Electrical and control system (ECS) in the electrical department.

This department is banished by the time. After that, the department name is changed

to PE & OLIFAN. The objectives of this Company are several such as ensuring

safety, Health and environment management system, High reliability operation,

effectively employ Saudi nationalities train them to provide them career developed

programmed and quality.

Sharq Safety:

In 19/6/2012, I attended the safety lecture in order to know the safety rules that must

be followed to work safely in Sharq without any injuries. The following rules are:

Safe yourself in order to save the environment.

The prohibited items are: lighters, mobile phones, recorders, radio.

Smoking is not allowed.

If you're in a plant, you can go the other plant by specific bus.

Furthermore, I must wear Sharq shirt & trouser. Also, Safety helmets and safety shoes

in the plants, or substations are required.

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Root cause analysis:

In 20/6/2012, I attended a lecture which is about root cause analysis "RCA". This

lecture is about analyzing the problem and gives solutions for it, then ideal decision

for the problem.

RCA steps:

Understanding the problem.

Gathered data related to incident.

Analyze (Logic Tree).

Verify.

Identify Cases.

Generate recommended actions.

Team review with a sponsor.

Presentation to responsible person departments.

Implement recondition.

Observe effectiveness.

Revisit RCA / reaction.

Heat Stress Announcements:

These warning for the workers and when you will hear" May I have your attention

please" then he will mention the heat stress number (1, 2, 3, 4)

Heat stress Working Stop Working

1 45 min 15 min

2 30 min 30 min

3 15 min 45 min

4 - No working

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Sharq substations layout:

Activities and responsibility:

I was asked to attend the daily activity at the morning every day. In addition, the

technician are explaining the problems and the devices that needs to be fixed or

changed such as motors, Valves, UPS and measuring insulation resistance between

phases in order to check the short circuit. There wasn't any responsibility for me as a

student because I am participating. The electrical engineer at Sharq is responsible for

any problem that occurs at substation and plants such as trouble shooting, short

circuit, testing the generators and changing relays and any kind of electrical problems

as previously mentioned. The manager Nasser AL-Mutairy asked me to write weekly

report and monthly report about what I am learning from this Company. The weekly

230KV S/S

Recever from SECCO

SG TYPE: GIS SIEMENS

115KV S/S

V: P-230KV/S-115KV

SG TYPE: GIS MITSUBISHI

1 MAIN

1 S/S

V: P-115KV/S-34.5KV

SG TYPE: SF6 CB MITSUBISHI

3 S/S

1UTL

4 S/S

1EG

1EG COMPRESER

1KM-1201

5 S/S

1PE 1T.P.S

7 S/S

Administer + MTC + NEW WAREHOUSE

13 S/S

1PE 2T.P.S

2 MAIN

10 S/S

Voltage: P-115KV/S-34.5KV

SG TYPE: SF6 CB SCHNEIDER

11 S/S

2UTL

12 S/S

2EG

2EG COMPRESER

2KM-1201

21 S/S

3UTL

3 MAIN

20 S/S

V: P-230KV/S-34.5KV

SG TYPE: SF6 CB MITSUBISHI

23 S/S 2PE 3 T.P.S

3EG COMPRESER

3KM-1201

33 S/S

3PE

22 S/S

3EG

4 MAIN

30 S/S

V: P-230KV/S-34.5KV

SG TYPE: SF6 CB ABB

32 S/S 4EG

V:P-34.5KV/S-13.8+4.16+480

SQUER D

31 S/S 4UTL

V:P-34.5KV/S-4.16KV+480V

SQUER D

38 S/S 4UTL C.T

V:P-34.5KV/S-13.8+4.16+480

SQUER D

34 S/S 4PE

V:P-34.5KV/S-13.8+4.16+480

SQUER D

36 S/S OLF

V:P-34.5KV/S-4.16+480

SQUER D

4EG COMPRSER

4KM-1201

V:P-34.5KV/S-13.5KV

SQUER D

37 S/S OLF

V:P-34.5KV/S-4.16+480

SQUER D

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reports must be submitted to my supervisor Abdullah Al-Baghdadi and the monthly

report must be submitted to the manager.

Major tasks:

In 27/6/2012, I was asked to go with one of the technician to see how to change of the

relays in substation 34. It's the relay multiline 750 for the feeders in the low voltage

switch gear (480V). To change the relay, there are some steps that must be followed:

Isolate the required relay from the system.

Download the settings from the old relay to a portable laptop.

Upload the settings to the new relay.

Replace the new relay

Connect the relay by closing the Isolators and ATS execution button buttons.

In 29/7/2012, I was asked to see how they test the emergency generator1-G-8001 A,

B; C. which is located near to substation 36. Usually they test the three generators,

weekly without loads, and monthly without loads. In addition, each generator are in

series with vacuum circuit breakers. (See the single line diagram in the appendices)

There is a DMC that has a touch screen for the three generators. Furthermore, the

generators are feeding the bus bar in the MV switch gear (4.16kv)

.

DMC Touch Screen

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Conclusion:

In conclusion, the internship period in Sharq Company was excellent for me in terms

of knowledge, experience, and practical life. The major tasks that I was asked to study

and observe were good for me to gain experience and not commit any mistakes in the

future. The plan that they gave me was about power system analysis. The engineer

must seek for the information by himself, so he won't forget it. Ultimately, the

company supported me to see the world of electrical works.

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References:

1. "Protection system" Maintenance procedures, Sharq Maintenance Department.

2. "Cathodic protection" Maintenance Procedures

3. ALmaliki, Jabir. Personal Interview, 25/6/2012.

4. Al-Mutairir, Nasser, Personal Interview, 8/7/2012.

5. "UPS & charger'' Manual, Sharq Maintenance Department

6. "VVVF" Maintenance procedures, Sharq maintenance department

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Appendices:

Short circuit calculations:

a. Impedance for transformers:

R p.u= R%* (1-impedance of tolerance) */ Machine Kva *100

X p.u= X% * (1- impedance of tolerance) * Base KVA/ Machine * 100

b. Impedance data of cable and Bus ducts:

R p.u= R Actual * Base MVA / (base KV) ^2

X p.u = X Actual * Base MVA/ (Base KV) ^2

c. Short circuit current:

I sc = base MVA / (√3 * Base KV * Zp.u)

Voltage Drop Calculations:

a) Percent of impedance:

Z% = ZA * KVA base * 100 / KV^2 * 1000

Where,

Z% = impedance, in percent

(Same equation for % R and % X shall be applied)

ZA = Actual impedance, in ohms

KVA base = Base KVA (1000000 KVA)

KV = System base voltage (13.8Kv, 4.16 KV, 0.48 kV, respectively)

(b) Voltage drop is calculated as follows:

E% = KVA/ KVA base * (%R CosΩ + X % SinΩ)

Where,

E% = Voltage drop, in percent

KVA = Actual load apparent power, in KVA

KVA base= Base KVA (1000000 KVA)

% R= Resistance, in percent

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% X = Reactance, in percent

cosΩ = Power factor, in decimal

SinΩ = reactive factor, in decimal

(c) Impedance Data of transformers:

% R= %R act * (1+ impedance tolerance) * Base KVA/ Machine KVA

% X = %X act * (1+ impedance tolerance)* Base KVA/ Machine KVA

(d) Impedance of date of cable and bus ducts:

% R= R act * Base KVA/ (Base KV) ^2 * 10

% X= X act * Base KVA/ (Base KV) ^2 * 10

(f) To calculate equipment rated voltage:

Voltage drop= e% *(Rated system voltage)/(100)

Equipment rated voltage = Rated System voltage- Voltage drop.

Cable sizing calculations:

Calculation Steps:

1. 1. Finding the continuous current:

I= P/ (Voltage * CosΩ)

2. Capacity of cable = Cable * Rating of cable

3. Voltage drop (VD) = I (%R CosΩ+ X% SinΩ) * L/ 1000

4. Maximum length of cable= VD * 1000/ I (R cosΩ+ X sinΩ)

Where:

I Current in Amps (A)

R cable Resistance in ohms per kilometer (Ω/ Km)

CosΩ power factor of equipment

L Length of cable

X Cable reactance at 60 HZ in Ohms per kilometer (Ω/ km)

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Single line Diagram (From Sceco Side)

Emergency Generators

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Appendix C: Industry Supervisor Report

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Appendix D: Student Feedback Form

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Appendix D: Student Log Sheet

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Progress Report 1

Prince Mohammad Bin Fahd Univers i ty

C o l l e g e o f E n g i n e e r i n g

Department of Mechanical Engineering

Internship Report

at

Sabic- Sharq

R e p o r t i n g P e r i o d :

[16/6/2012 - 15/8/2012]

S u b m i t t e d b y :

K h a l i d A L - H u s s a i n

[ 2 0 0 7 0 0 2 6 3 ]

[ s u b m i s s i o n d a t e ( 9 / 7 / 2 0 1 2 ) ]

Electrical Engineering Department

Summer 2012

Internship Report

29Page

Summary:

Sabic Company is established in 1976 by royal decree. Its task is setting up operate

hydro carbon and mineral based industries in KSA and transferring them to good

value. This will assist the kingdom in terms of industrial base.

Back ground:

In 16/ 6/2012, I went to ALRazi to sign my papers to work in Sharq. Further, I went

to the maintenance building to meet my supervisor to know what I have to learn from

this training. The name of the company is Sabic and I am working in Sharq at ECS,

Electrical Department. Abdullah AL-Baghdadi is my supervisor and I can contact him

by the following information: email: BaghdadiAA@sharq.sabic.com, T: +966 (3)

357 5000-5862 Ext.5862, F: +966 (3) 357 5275, Job: Electrical engineering. P.O.

Box 10035, Mobile: +96655468875,

In the first week, the supervisor asked me to go through Power system by GE training

Software that is helpful for enhancing my Knowledge about my field. Also, I must

attend the safety orientation lecture to know the rules. The second week, I was asked

to go to substations to relate theoretical studies to practical life.

Progress:

First week:

1. Attending the SHE orientation to learn the following: (19- june-2012)

Safe yourself in order to save the environment.

The prohibited items are: lighters, mobile phones, recorders, radio.

Smoking is not allowed.

If you're in a plant, you can go the other plant by specific bus.

Moreover, I must wear the Sharq shirt and trouser. In the plants, the safety shoes and

helmet are significant.

2. Root Cause analysis lecture" RCA": (20-June-2012)

I learned the following steps:

Understanding the problem.

Gathered data related to incident.

Analyze ( Logic Tree).

Verify.

Identify Cases.

Generate recommended actions.

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Team review with a sponsor.

Presentation to responsible person departments.

Implement recondition.

Observe effectiveness.

Revisit RCA / reaction.

3. GE training software:

I went through power system analysis and Distribution system.

Second week:

I went to the following substations:

Substation 38:

I saw the following:

Switch Gear:

There is a Medium Voltage Switch gear (13.8KV) and low voltage switch gear

(480V). Each switch gear has Protective Relays such as 750 relay for the feeders, 745

for the transformers, and the 469 relay for the motors. Also, switch gears has Circuit

breakers, ATS, and Relay test blocks which used for testing the relays.

Motor Control center (MCC):

It's the same as switch gear, but it has contactors instead of circuit breaker and fuses

for protecting over currents. 469 relay.

Charger:

There is an input MCCB switch will allow the rectifier to work to convert from Ac to

dc to charge a battery for emergency. If any dc control in fails, the battery will feed it.

UPS:

A UPS has rectifier and inverter. Rectifier will convert from ac into a dc to allow the

battery work, and then inverter will convert from dc to ac again. If it fails, the Bypass

MCCB will work, so the transformer will feed the load. If an ac device fails, the UPS

will feed it.

Substation 3:

It's the same as other substations, but the switch gears have an old relays such as relay

27(Under voltage relay), relay 49(Transformer thermal relay), relay 50(Over current

relay), 51 and (Over current) and 52 (Air circuit breaker). Also, a potential

transformer used for high voltage and low voltage.

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Substation 31:

It has same things as substation 38, except that it doesn't has fixed capacitors and

UPS. But, there is an emergency ABB transformer.

Problems:

a. In substation 3, the problem is the GE Multilin 750 relay in switch gear

(480V-Low voltage) must be changed, which is for the feeder. The setting

must be downloaded to pc from the old one, then down load it into the new

relay.

b. In substation 31, there was short circuit for one of the three phase motors. The

technician used an insulation resistance device to measure the insulation

between two phases and also for each phase with ground. Ultimately, he

discovered short circuit between one phase and ground.

Plans:

The supervisor gave me a plan for two months. In addition, I must submit weekly

report and two monthly reports to him and attending daily activity.

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32Page

Progress Report 2

Prince Mohammad Bin Fahd Universi t y

C o l l e g e o f E n g i n e e r i n g

Department of Electrical Engineering

Internship Report

at

Sharq Company

R e p o r t i n g P e r i o d :

[30/6/2012-11/7/2012]

S u b m i t t e d b y :

K h a l i d A L - H u s s a i n

2 0 0 7 0 0 2 6 3

s u b m i s s i o n d a t e ( 1 3 / 7 / 2 0 1 2 )

Electrical Engineering Department

Summer 2012

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33Page

1. Summary:

Protection system is crucial in terms of protecting our equipments in substations. In

addition, Power System, calculation required for designing the system and this is I

suppose to know as electrical engineer.

Back Ground: 2.

Protection system is the ability of sensing a fault to take an appropriate action within a

time frame necessary to minimize damages, interruption power, and Safety issues.

Going to substations to see the devices in reality is helpful to understand.

Furthermore, Load flow studies, short circuit calculations, voltage drop calculations,

Cable sizing calculations and power factor study are significant in the world of power

electrical engineering. These are the things that my supervisor asked me to do in two

weeks.

Progress: 3.

According to my plan, the supervisor asked me to do the following tasks:

Week3:In

I was assigned to study the protection devices before going to the substations.

Protection devices:

First, the current transformer is used to step down a current to the relay to check if

any faults occur, so the breaker will open to clear the faults. Second, the Voltage

transformer that will step down a voltage to relay to do what previously mentioned.

Third, differential relay, which work by adding two current transformers and a

transformer between them, and thus a differential relay will see the difference

between the primary current and the secondary current. If the difference occurs, then

the relay will make the breaker to trip.

Other protection equipments such as fuses are helpful to clear a fault over current in

the system. If it fails, the circuit breaker can clear. Fuses are available, in the MCC,

and many places.

c transfer Switches):ATS (Automati

Useful for two sections in switch gears. For instance, breaker in section A and other

breaker in section B and the third is between. The two breakers in section A and B are

normally closed and the third is normally open. The ATS is able to close the third

Breaker manually or automatically and open A and thus B will feed the feeders. It is

also able to do the opposite and make A feeds the others. What is more, the

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synchronism relay can sense to indicate which section has a problem, so we can stop

this operation.

Substations:

I went to substation 5 to see the VVF and what is it for, Relay 25 (Synchronism

relay), CT and VT, Relay 86(Differential relay), Relay 50G (Over Current Relay),

two neutral ground resistance (A &B) and Selector switch of RTD in MCC.

I went to substation 3 to see, Relay 50(Over current relay), Relay 51(AC Time Over

, Relay 25 (Synchronism Relay) Relay )current Relay), Relay 27(Under voltage Relay

86 (Differential relay) Two neutral ground resistance: 3GD-1A, 3GD-1B for (3TX-A)

and (3TX-1B).

Week 4:In

I was asked to study the following:

Short Circuit:

Short circuit is a fault over current that occurs between two phases or phase and

ground. Usually, the short circuit happens as result of week insulation or improper

wiring of broken insulation.

Conditions of calculations:

1. The actual circuit must be converted into per-unit impedance circuit.

2. The impedance of transformer, cables, bus ducts, etc. are required in per unit.

Other impedances such as breakers and CT are neglected.

3. Using an appropriate theory or analysis to calculate the short circuit faulty

current.

Voltage drop:

The purpose is observing the voltage difference between the supplied voltage and the

drop voltage at the bus bar or the load.

Conditions of calculations:

4. Drawing the equivalent of per unit impedances for each element of the circuit.

5. Impedance of transformers, cables, bus ducts, etc are required. Impedances of

transformers, etc. are neglected.

6. Applying mathematical equations to calculate the percentage drop.

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Cable sizing calculation:

It's crucial to calculate the cable length and size to deliver appropriate current, voltage

and power flow to the motor.

Steps of calculations:

4. Finding the continuous current.

5. Finding the voltage drop across the cable.

6. Calculating the Maximum length of cable.

Power factor study:

When the load is inductive (Lagging power factor), the capacitor can enhance the

voltage conditions, reducing the current, reducing line losses and reducing power bills

and ultimately leading power factor. The perfect power factor is close to one.

Load Flow Calculations:

Load flow calculation is about studying Voltage Profile, Power Flows, Current Flows,

Power Factors, Transformer LTC Settings, Voltage Drops, Generator’s Mvar Demand

(Qmax & Qmin), Total Generation & Power Demand, Steady State Stability Limits,

MW & Mar Losses.

4. Plans:

I was assigned to attend daily activity and writing a weekly report about the work

done in these two weeks. The next two weeks will be about Transformers and VVF.

5. Conclusion:

In conclusion, protection system is helpful to avoid equipments damages, hazards, and

fault currents and thus the substations and plants are under control. Power system

calculations and studies are helpful in terms of designing perfect plants equipment.

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Prince Mohammad Bin Fahd Universi t y

C o l l e g e o f E n g i n e e r i n g

Department of Mechanical Engineering

Internship Report

at

[Sabic-Sharq]

R e p o r t i n g P e r i o d :

[14/7/2012 - 25/7/1012]

S u b m i t t e d y :

[ K h a l i d A L - H u s s a i n ]

[ 2 0 0 7 0 0 2 6 3 ]

[ s u b m i s s i o n d a t e ( 2 7 / 7 / 2 0 1 2 ) ]

Mechanical Engineering Department

Summer 2012

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37Page

Summary:

I was assigned these two weeks to study about transformers and VVF. My supervisor

noticed that it's hard to cover the requirements in two month. Therefore, it seems that

I will have a beneficial pressure, so he asked me to do other things. My assignments

in these two weeks are about transformers and Basics trainings.

Back ground:

According to my plan, I have to learn more about transformers in the fifth week, but

my supervisor asked me to seek for other details because of the short period. The

week after, I was assigned to see the basic trainings in the company. Though it's hard

to cover the majority of heavy, I was motivated to try to learn as much as I can from

them. Moreover, I am joining a small group in the basic training.

Progress:

My assignment in these two weeks:

Plan work Period

Transformers, Generators, GIS 14/7/2012-18/7/2012

Basic Training 21/7/2012-25/7/2012

Week 5:

Transformers:

The main purpose of transformers is either steeping down or stepping up. This

depends on the on what is needed for the load. Usually, transformers feed substations,

three phase motors, transmission lines, etc. there are two types of transformers. The

first type is the dry type transformer. The second type transformer is liquid filled type.

Dry type of transformer:

The dry type of transformer has limited size around 10 MVA because it relies on air

to provide cooling and its losses are high. Further, It can be designed to operate at

much higher temperature than Liquid-filled (temperature rises as high as 150oC,

whereas oil filled as 100oC to avoid acceleration of breakdown of oil).

Liquid filled type:

This type of transformer is relying on oil. There is sealed type and non- sealed type.

Sealed type:

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The sealed type has a temperature gauge. When the temperature is increasing, the size

of the oil will be increased and thus the air will go out with the moisture. The nitrogen

gas and oil and oil will be inside the tank and that's why we call t sealed. On the other

hand, the non-sealed is not closed as the sealed one and it has there is a breather.

Brief description about oil filled type equipments:

The breather of the transformer absorbs the moisture by silica jell. The radiator of the

sealed type is for cooling the oil. The bushings are above the terminal box to hold the

cables, and insulate between the cables and the box to avoid short circuit. Tap changer

which is located in the primary windings to switch and control the voltages. There are

two types of tap changers. ON load tap changer and off load tap changer.

Gas insulated switch gear:

It is the upstream of the substations. A gas (SF6) insulated substation may have

underground feed lines and be nearly invisible to the average person. Distribution

circuits supplied by gas insulated substations normally have an alternate feed from

another substation, to allow maintenance work on the gas insulated site. For instance,

Sceco is feeding Sharq Company and the GIS will feed transformer to feed

substations. (See figure 1)

Generators:

The generator has an exciter which is series to the load will produce a magnetic field

to the stator windings. Then, the induced voltage in the stator winding that ends

currents will be delivered to the load. There is a prime mover will produce steam for

the turbine to rotate and ultimately the generator will rotate. Therefore, the generator

converts the mechanical energy into electrical energy. There are other sources of

generations such as hydro-electric, nuclear, fossil fuels, and diesel engine. (See

figure2)

Week 6:

There is a basic training that I have to attend in order to enhance my knowledge about

my major. It was interesting training that I've ever seen in my university life.

Furthermore, the instructor was expert to teach this course.

Fluorescent lights:

There are two types of fluorescent lights. The first is t is preheat type, when the circuit

is energized the current will flow from cathode A and then to cathode b through the

starter and there will heat the gas inside the lamp and thus an arc will occur across the

fluorescent lamp. The second is the rapid. The rapid start ballast will deliver a small

voltage to heat the cathodes. There isn't starter needed and cathodes will heat the gas,

so the gas will be increased and higher current and lower resistance.

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Mercury Vapor and Sodium:

The ballast will deliver a voltage to the electrodes. The starter resistor will control the

current flowing. An arc will be struck between the starting electrode and the two main

electrodes. Therefore, the current will be high and resistance and that makes the

mercury vapor increased. Ultimately, the lamp is working. Sodium vapor doesn't have

the starting resistor and electrodes, but only two main electrodes. However, there is an

igniter that will deliver high voltage and high frequency to the electrodes and heat the

sodium vapor and arc will occur to make the lamp work.

Single Phase Motor:

The supply voltage will deliver current which will go into two loads. The first load

has Capacitor, Centrifugal switch and starting winding. The second load has running

winding. The current will flow through the capacitor and centrifugal switch and then

starting winding. The starting winding will produce a magnetic field to make the rotor

rotate. When the rotor reaches the required speed, the centrifugal switch will open.

The running winding will make the rotor to continue rotating. The purpose of having

the capacitor in the circuit is maintain the wattage, voltage , and also to make phase

shift between the running period and starting period is 90.

Plan:

I was supposed to learn about transformers and VVF this week. But the supervisor

asked me to do more as a result of the short period. The supervisor is a good person

who is helping for my future.

Conclusion:

In conclusion, the generator will generate power to the GIS, and the GIS will feed the

transformers that will step down voltages for the substations. The Basic training

course was helpful for me to enhance and improves my knowledge. The engineer

must seek for the information by himself to learn.

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Appendices:

GIS in ABB:

Figure 1

Generators performance:

Figure 2

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11Page

Prince Mohammad Bin Fahd Universi t y

C o l l e g e o f E n g i n e e r i n g

Department of Electrical Engineering

Internship Report

at

[Sabic-Sharq]

R e p o r t i n g P e r i o d :

[28/7/2012 - 8/8/2012]

S u b m i t t e d b y :

[ K h a l i d A L - H u s s a i n ]

[ 2 0 0 7 0 0 2 6 3 ]

[ S u b m i s s i o n D a t e ( 1 0 / 8 / 2 0 1 2 ) ]

Electrical Engineering Department

Summer 2012

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12Page

Summary:

I was assigned in the last two weeks to study the Cathodic protection and VVVF.

Also, I was assigned to go with my supervisor to see the emergency Generators in

order to test them and How their performance.

Back ground:

The buried Pipelines are in the underground need to be protected from the corrosion

that leads to the erosion. By the cathodic protection methods, the metal pipes will be

in a safe situation from falling down and short circuits problems. In Sharq, they are

testing the emergency generator weekly without load and monthly with load. The

purpose of having VVVF is controlling the speed of the motor.

Progress:

Plan work Period

Cathodic protection, Testing Generators 28/7/2012- 1/8/2012

VVF 4/8/2012-8/8/2012

Table 1

Week 7:

Cathodic protection:

Cathodic protection is a technique which is useful to protect the metals such as,

Buried pipelines, Storage tanks and reinforced concrete from the corrosion. There are

two beneficial methods are useful to protect our sources from the corrosion. The first

method is impressive current method (ICCP). The second method is the sacrificial

anode method (SACP).

The Impressive Current Method:

For larger structures, galvanic anodes cannot deliver enough current to provide

complete protection. The Impressive Current method uses anodes connected to a DC

power source. The rectifier bridge is useful to convert from ac source to dc powers

source. At the end of the rectifier bridge circuit, there are two terminals. The positive

terminals for the anode for decaying and the negative terminal are for the cathode for

protection. Ultimately, we can protect the Pipe lines from the corrosion and avoiding

short circuit.

Sacrificial Anodes Cathodic protection:

If we add the Fe to a carbon, it will become hard steel. In addition, the magnesium

will be a good solution to avoid the corrosion. The magnesium can be considered as

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the anode part for decaying, and the steel can be considered as the cathode part for

protection.

Problems:

I went with my supervisor to see him how is going to test the three generators in the

Emergency generators building which is near to Substation 36. There was a DMC that

controls the generators and it has Touch screen to control the Three Medium voltage

generators 1-G-8001 A, B; C. the three (4.16 KV) generators are in series with three

Vacuum circuit breakers to feed the bus bar MV switch gear . The switch gear is in

substation 36.

Week 8:

VVVF:

The variable voltage variable frequency is electronics power device which is able to

control the speed of the motor. Adjusting the speed is crucial for some reasons such as

machine or Process Requirements, Energy Savings, Automated Factory Concept and

Productivity Increases.

The components of the VVVF:

The components of the VVVF are many such as integral transformer, Rectifier,

inverter, control circuit, cooling fans, Display/ Key and Isolation. (See the

appendices).

Plan:

My supervisor asked me to see the emergency generators in week 7. Also, I went

with one of the technician to substation 5 to see the variable voltage variable

frequency.

Conclusion:

In conclusion, the cathodic protection is special technique to protect the buried

pipelines and other metals form the corrosion. Further, it's a good experience to for

me to see how they test the emergency generators. Variable Voltage Variable

frequency is panel is useful the control the speed of the motors.

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Appendices:

Figures:

Figure 1

Inverter (Convert DC to AC with different frequency)

Figure 2

Control circuit

Figure 3

Cooling fans

There are two group fans and each group has two fans. Each group is

redundant.

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Single Line Diagram :

Figure 4

Emergency Generators