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POWER HOUSE, MOTORS & MOTORS C0NTROL

By

BABAR SALEEM

Reg. No. 2013-GCUF-03768

B-Tech (Pass)

Electrical Technology

Session: 2013-2015

Distance Learning Program

Government College University Faisalabad

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Dedication

I dedicate my work to my parents who made me from nothing to what I am today. Their prayers are with me at every moment of my life and to my teachers who are the become of knowledge. They helped me to determine the path of glory and in last to those people who helped me in fulfillment of goals developing personality and knowledge and development of my knowledge personality.

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ACKNOWLEDGEMENT

First of All I thank Almighty Allah, The Compassionate and The Most Merciful, who bestowed on me the potential and ability to complete this Project. All and every respect is for His Holy Prophet MUHAMMAD (Peace be upon him), whose teachings enabled us to recognize out creator.

I wish to express my sincere gratitude to MR. UBAIDULLAH project advisor for his support and encouragement.

I am thankful to my seniors, colleagues and all my friends who helped me directly or indirectly for their support.

Babar Saleem

B-Tech (Pass) Electrical

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FINAL APPROVAL

It is to certify that we gone through this project

Submitted by

Babar Saleem

Reg. No.2013-Gcuf-03768

Roll No.14017

B Tech. (Pass) Electrical

Our judgment is that this project is up to the standard to warrant its acceptance by the

Govt. College University, Faisalabad

for B-Tech Pass degree in electrical Technology

PANNEL OF EXAMINERS

External Examiner : ____________________________

Coordinator: Mr. Ubaidullah

Director Distance learning : Dr. Naeem Mohsin.

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Power House, Motors & Motor Control system

Contents

1. Introduction of company1.1. Department of company

2. Power House Gas Engine2.1. Excitation System2.2. Differential Protection2.3. Synchronizing System2.4. Advantages of Synchronization

3. Neutral Ground Resister (NGR)4. Auto Load Shedding (ALS) System

4.1. ALS System for H.F.O. Generator4.2. ALS System for Gas Generator4.3. 1st and 2nd Priority Relays for ALS System

5. Substation5.1. Vacuum Circuit Breaker (VCB)5.2. Air Circuit Breaker (ACB)5.3. Bus Bar5.4. Operation of Circuit Breaker5.5. Load Break Switch (LBS)5.6. Power Factor5.7. Capacitor Bank5.8. Protective Relays5.9. Magnetic Contactor5.10. Fuses5.11. Panels5.12. Feeders5.13. Transformers

6. Motor6.1. Induction motor

7. Motor Starters7.1. Direct Online (DOL) Starter7.2. Star Delta Starter

8. Utility (UTY) Department8.1. Compressors

1. Introduction of company

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Al-Muqeet Textile mill established in 2007 . Al-Muqeet a composite textile mill,

initially operated on a very modest scale at industrial state Nooriabad Karachi.

1.1. Department of Company

There are nine major departments working in Al-Muqeet Textile Mill is as under,

1) Mixing

2) Blow Room

3) Carding

4) Drawing

5) Simplex

6) Ring

7) Auto Cone

8) Power House

9) Electrical & Electronics

2. Power House Gas Engine

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There are two gas engine generators in Al-Muqeet Textiles Mill Plant.

The rating of gas engine generator’s are as follow:

4000 KVA 50 HZ

11000 V P.F 0.8

2.7 MW 210 A

1500 R.P.M

There are batteries for servo motor rotation. There is a jacket water motor for cooling purpose temperature of jacket water.

The gas engines are controlled by SCADA panels and synchronizing in these generators are on auto basis.

We prefer to use gas engine’s due to low per unit cost rather than H.F.O and WAPDA supply.

2.1. Excitation System

When engine is start running and after achieving 85% speed i.e. 510 R-P-M 53x relay will energized. The relay will change its contacts.

Excitation is provided by batteries. When terminal voltages 85V, the relay 84 will energized and change its contacts now self excitation will start.

2.2. Differential Protection

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The scheme of differential protection is used the circulating current principle. According to this current at two ends of protected section are compared with the help of CT’s.

Under normal condition current at two ends are equal. If current vary on both ends due to any fault. Difference of current is arranged to pass to through the corresponding relay coil.

The relay will energized and change its contacts thus the supply passed to shunt trip coil of Circuit breaker , which cause to trip the circuit breaker.

Identical sets of CT’s are placed on each phases on both sides.

In Al-Muqeet Textiles Mill Plant differential protection is used to protect engines and generators.

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2.3. Synchronizing System

To connect a generator with another generator in parallel or to connect two generators with a single bus bar is called synchronizing.

The Conditions Required For Synchronizing:

The conditions required for synchronizing are as follow:

1) The phase voltage of both generators should equal2) The phase sequence of both generators should same3) The phase angle of both generators should same4) The frequency of new on coming generator must slightly higher

than the running system.

In Al-Muqeet Textiles Mill Plant:

When the load is on, 1st generator and if we need more power. We will start one more generator on no load. We increase the frequency of new on coming engine from 0 to 50 HZ, according to first on load running engine.We see voltage of both generators producing on volt meter, which we get from PT (Potential Transformer), which are installed on generation cables.On generator rotor, a techo generator is installed, which shows us the frequency of rotor of on HZ meter.The phase angle and phase sequence of three phases of both generators will seen by synchroscope.When these all conditions are cleared, we switch ON the VCB (Vacuum Circuit Breaker) of new on coming generator to attach it with bus bar.After this we transfer load equally on both engine from GCP.

2.4. Advantages Of Synchronizing:

The advantages of synchronizing are as follow:

1) Two generators can supply bigger load then a single generator.

2) Having many generators in parallel increasing the reliability of full system

3) The failure of any one generator of them does not cause a total power lose to the load.

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4) Having many generators operating in parallel allows one or more of them to be removed from system for shut down preventive maintenance.

5) If only one generator is used and and it is not operating at near full load, then it will relatively inefficient.

With several smaller generators in parallel, it is possible to operate a fraction of them.The one that do operate are operating near full load and does more efficient.

3. Neutral Ground Resister (NGR)

In Al-Muqeet Textiles Mill Plant, power house department the neutral of all H.F.O generators are attached with each other and then grounded through NGR (Neutral Ground Resister).

NGR Neutral Ground Resister is used to limit the ground fault current.

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4. Auto Load Shedding (ALS) System

ALS (Auto Load Shedding) system is installed in power house and substation department. Whenever any heavy fault occurs on any running engine (Which cause to stop the engine).

ALS system will cut OFF the load of selected load on ALS system automatically.

4.1. ALS System for Gas Generator

When a gas generator trips, the normally open contact of ALS closes. The normally close contact 60K3 remains close as the generator breaker is close.

Now relay R1 energizes and two inputs are sent to PLC.

We know that for two inputs of PLC both 1st & 2nd priority relays will operates.

4.2. 1st and 2nd Priority Relays for ALS System

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In ALS system when 1st priority relays operates

N.O (Normally Open) contacts 83-1X close and relay coils A & B energizes. N.O contacts of A & B relays will close and energizes relay coils D & E. These relays (D & E) when energizes. They energize the number of trip coils

of circuit breakers and cut the load from system.

This is how 1st priority operates.

In ALS system when 2nd priority relays operates

N.O contacts 83-2X closes and relay F energizes and the indication light of ALS operates is ON.

The N.O contact of F relay will close. The supply passes to relays R1 to R16, R1 to R16 relays will energizes. These relays energize the number of trip coils of circuit breakers.

5. Substation

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Sub-Station is a central point between Power House and loads.

In Al-Muqeet Textiles Mill plant Sub-Station, we receive high voltages (11KV), from Power House and WAPDA.

Ten we convert HT voltages to LT voltages (11KV to 400V) with transformers and then forward it to loads.

The main power switchgear of loads are at Sub-Station, after this the supply pass to departments. There are the panels, which have full control system of that machine. The panels are based on star delta circuits; some are based on PLC and Inverter.

Following are the main purpose of Sub-Station:

1) Switching2) Protection3) Improving power factor4) Converting the power

Following are the switchgears for Sub-Station:

1) Circuit breakers2) Fuses3) Relays4) Current transformers ( CT )5) Potential transformers ( PT )6) Load break switches ( LBS )7) Power factor improving panels8) Transformers

Following are the measuring instruments and indications of Sub-Station:

1) Volt meters2) Ampere meters3) Ohm meters4) CT & PT5) Indication lights

5.1. Bus Bar

Bus bar is such a conducting bar by which many feeders, distribution circuits and supply sources are attached. Bus bar is working on permanent voltages.

Bus bar is a bar of copper. Its main purpose is to conduct electricity.

5.2. Operation of Circuit Breakers

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Circuit breaker is an automatically operated switch in case of fault.

It is designed to protect an electric circuit from damage caused by over load and short circuit. Its basic function is interrupt current flow in fault condition.

All circuit breakers have common features in their operation, although details vary substantially depend on voltage class, current rating and type of circuit breaker.

When current is interrupted, an arc is generated. This arc must be contained cooled and extinguished in a controlled way. So that the gap between the contacts can again withstand the voltage in the circuit.

Circuit breakers are usually able to terminate all currents very quickly, typically the arc is extinguished between 30 ms and 150 ms after the mechanism has tripped, depending on the construction of device.

5.3. Vacuum Circuit Breaker (VCB)

VCB have minimal arc (as there is nothing to ionize other than the contact material). So the arc quenches when it is stretched a very small amount. VCB are frequently use in our Sub-Station to 11 KV.

VCB used on HT side at Sub-Station and power house.

The rating of VCB as follow:

1) 11 KV2) 630 A3) 25 KA

5.4. Air Circuit Breaker (ACB)

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Air circuit breaker may use compressed air to blowout the arc or alternatively the contacts are rapidly swung into a small sealed chamber. The escaping of displaced air thus blowing out the arc.

ACB used on LT side at in Al-Muqeet Textiles Mill Sub-Station.

The rating of ACB as follow:

For 2000 KVA transformer

3200 A, 400 V

85 KA

For 2500 KVA transformer

4000 A, 400v

85 KA

5.5. Load Break Switch (LBS)

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LBS is an additional protection, used before VCB. We have three LBS on HT side Al-Muqeet Textiles Mill plant Sub-station. Which have ratings as follow:

11 KV, 400 V

12.5 KA

5.6. Power Factor

The power factor of an AC power system is defined as the ratio of Active power and Apparent power.

P.F = True power / Apparent power

In Al-Muqeet Textiles Mill plant Sub-Station, there are five power factor panels. Two power factor improvement ( PFI ) panels are installed between WAPDA supply. Three PFI panels are installed between generation supply panels.

The ratings of power improving units are as following:

1) 750 KVAR2) 850 KVAR3) 850 KVAR4) 650 KVAR5) 850 KVAR

Following are the ratings of fuses used in power factor panels:

125 A, 500 V

120 KA

Following are the rating of capacitor from PFI panels:

50 KVAR, 75 A

400 V

5.7. Capacitor Bank

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5.8. Protective Relays

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Protective Relay is a device which is used between the main circuit and circuit breaker in such a way that, in case of any abnormality the relay sends the signal to the circuit breaker for tripping.

Faulty element will be separated by tripping of circuit breaker.

5.9. Magnetic Contactor

The Magnetic Contactor is an electromagnetic device. It is used to make and break the circuit.

It has 110 V DC or 220 V AC or 24 V DC supply for its coils. When supply passes to coil of magnetic contactor, the coil will work like a magnet and towing the core.

By this way the supply pass from power contacts of magnetic contactor.

There are some auxiliaries contacts on contactor. Some are NO and some are NC. When the supply passes to contactor coil, the contact will change from NO to NC and NC to NO.

5.10. Fuses

This type of fuses are use in Al-Muqeet Textiles Mill plant Sub-Station for the protection of control circuit. This fuse consists of two parts:

1) A base having two terminals2) A fuse carrier

Cartridge fuse is tightened in a screwed fuse cap. The rating of this fuse is 6 A.

5.11. Panels

In Al-Muqeet Textiles Mill plant, there are fourteen panels on HT side in Sub-Station.

Four panels for feeders, three panels for LBS. there are nine VCB installed in HT side.

Relay, energy meters, fault indication lamps and breakers are installed in panels. There sixty panels in LT side. Forty nine panels are at A side and eleven panels at B side.

All load control switches are installed in LT side. Eight ACB and four Bus Coupler are installed in LT side panels. There are five power factor panels are installed in LT side. Two power factor panels installed between WAPDA supply. Three power factor panels are installed between generation supply.

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5.12. Feeders

There are four feeders come in substation from power house. There are two transformers on feeder no. 1, one transformer on feeder no. 2, three transformers on feeder no. 3 and two transformers on feeder no. 4.

In feeder no. 3, there is an interlocking between wapda supply and power house supply.

5.13. Transformers

Transformer is a static device. It is used to convert high voltage to low voltage (11KV to 400V), without changing frequency.

In Al-Muqeet Textiles Mill plant, there are only Step Down Transformers.

In power house department there are three auxiliary transformers. These transformers are of 630KVA.

There are eight transformers in substation department. 1 to 6 transformers are of 2000KVA ratings. 7 and 8 transformers are of 2500KVA ratings.

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6. Motors

An electric motor is an electric machine that converts electrical energy into

mechanical energy.

In normal motoring mode, most electric motors operate through the interaction

between an electric motor's magnetic field and winding currents to generate force

within the motor.

In textiles industries the induction motor is commonly used. The detail of induction

motors are as follow:

6.1. Induction Motor

An ac induction motor is popular in industry because of its simplicity and

ruggedness. In its simplest form, this motor is a transformer with the primary side

voltages connected to the Ac power voltage source and the secondary side shorted

to carry the induced secondary current. The name ‘’induction’’ motor drives from

this induced secondary current. The stator carries a three phase winding and the

rotor is a simple design, commonly called a ‘’squirrel cage’’ in which the copper or

aluminum bars are shorts circuited at both the ends by cast aluminum end rings.

The absence of rotor windings and brushes makes this motor design especially

reliable.

Rotor and stator of a induction motor.

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7. Motor Starters7.1. Direct Online (DOL) Starter

DOL starters are used in substation department for controlling exhaust fans.

The functional detail of DOL is as follow:

Cartridge Fuse is installed in power circuit for the protection of Motor.

The Contactor C energized by pushing the ON puss button and ON push button will come back in its original condition which is normally open.

During this, the normally open contact of Contactor C will close. Which is parallel to ON push button.

Similarly the contactor will energize through its holding contact and motor runs continuously even after leaving push button.

When we need to stop the motor, the OFF push button be pressed. This cause to de-energize the contactor and motor will stop running.

The holding contact of contactor will be opened because of de-energizing of Contactor C. During running of motor, if motor is overloaded, the contacts of overload will open and motor will stop working.

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7.2. Star Delta Starter

Star Delta Starter is used for motors which have rating of 4KW or more than 4KW.

The functional detail of Star Delta Starter is as follow:

The Contactor C energized by pushing the ON puss button and ON push button will come back in its original condition which is normally open.

During this, the normally open contact of Contactor C will close. Which is parallel to ON push button.

Similarly the contactor will energize through its holding contact. The supply passes to Timer and to Star Contactor by the way of NC of Timer. Now the motor is started running in Star. After the completion of set time of Timer, the Timer will change its contacts, which cause to ON the contactor of Delta and OFF the contactor of Star. While all of this, motor will run continuously.

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9. Utility (UTY) Department

In Al-Muqeet Textiles Mill Plant UTY department there are six compressor units. The compressed air of these compressor is used in other departments machines. The ratings of these compressors are equal to each other.

The ratings of these compressors are as follow:

P= 480 KW

A= 840 AMP

These compressors are controlled by Star Delta circuits.

7.1 Compressors

When all safeties are cleared, the supply card gives a signal to contactor K 6. Contactor K 6 is energized and cause to energize relay RM. relay RM will close its N.O contacts. The supply passed to timer T1 and to contactor of star C3. The N.O contacts of star contactor will close after energizing, the supply pass to contactor C1. The motor will star running in star connection.

After completion of timer set time, it will change its contacts and supply pass to transiant contactor C4. Transient contactor C4 will change its contacts and this cause to OFF the star contactor.

The supply passed to delta contactor C2, through the way of N.C contact of star contactor C3.

The motor is now running in delta connection.

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7.3.Cooling Towers

There are seven(7) Cooling Towers in UTY Department. The basic purpose of Cooling Tower is to cool the water for AC, Chiller, Spot Coolers and for the cooling Jacket water in HFO engines.

The motor of Cooling Tower Fans is auto and manually controlled from the panels. The Star Delta circuit is used to operate Cooling Tower Fan motors. The rated current of motors are 30A, 35A and 40A for different Cooling Towers.

The hot water from AC is coming back in Cooling Tower, after cooled down, the water will send to AC again. It is working like a cycle of water.