(FINAL REPORT)

OBJECTIVE:The objective of this course is to study about high voltage in power system. In this course we take a study tour in Energypac, which is a very well known name in the electrical power generation and distribution equipment market in Bangladesh. THEORY:To study about High voltage engineering at first we have to understand …

1. What is high voltage and its range?2. Different types of high voltage?3. Fields of applications of high voltage?4. What we learn in High Voltage Engineering?

1. What is high voltage and its range?

Ans:A mobile phone is operated from a 4V battery. It may be destroyed if anyone attempts to operate it from a 12V car battery. Therefore 12V is quite a high voltage for a mobile phone.

Below 11kV : Low voltage 11kV – 100kV : HV (high Voltage) 100kV – 400kV : VHV (Very high voltage) 400kV and above : EHV ( Extra high voltage) UHV : Ultra high voltage

2.Different types of high voltage?

Ans:Different types of high voltages are:

High DC voltages. High AC voltage of power frequency. High AC voltage of high frequency. High transient or impulse voltages of very short duration, such as lightning over

voltages. Transient voltages of longer duration, such as switching surges.

3.Fields of applications of high voltage?

Ans:Fields of applications of high voltage are..

Power system engineering. Research laboratories. Industries. Nuclear research, particle accelerators. Electrostatic precipitators. Automobile ignition coils. Medical applications like X-ray machine. Insulation testing of various components in power system.

4. What we learn in High Voltage Engineering?

Ans:From high voltage engineering we learn following technique_

Testing of HV equipments like power transformers, bushings, CB, insulators, cables etc.

Usually tests are done at a voltage much higher than the operating voltage. Generation, measurement and control of different types of HV. Failure mechanism of HV equipments caused by HV stress. Breakdown mechanism of different types of insulating materials ( solid, liquid,

gas, vacuum) under different types of voltages (ac, dc, li, si). Provide technical assistance toward designing HV equipments to be operated at

further higher voltages.

Here also we see different types of protection system like, Current and voltage transformers, Relays, Circuit breakers, Batteries, Communication channels.

REPORT ON ENERGYPAC:

INTRODUCTION:To study about high voltage engineering and protection of power system, we take a study tour in energypac at saver .which is a very well known name in the electrical power generation and distribution equipment market in Bangladesh.

COMPANY PROFILE:

ABOUT ENERGYPAC:

Energypac an ISO 9001: 2000 & 14001: 2004 certified leading manufacturer of Electro mechanical goods in Bangladesh. Energypac produces quality products by ensuring modern design and international testing facilities.

Energypac is the largest Power Engineering Company in Bangladesh. Energypac, today, is Bangladesh's largest private sector entrepreneur in power engineering equipments & extensively engaged in designing, manufacturing and marketing high technology electrical products and services related to power generation, transmission, distribution as well as executing turnkey projects.They are operating their business in this field for the last 25 years and now they are the largest and strongest manufacturer in this field. Energypac provide a full range of support including regular advance product information and shared promotional material, quality products, safety and reliability. They feel an extra commitment to providing quality care & their prices are very much competitive.

Since 1982, Energypac Engineering Limited provided professional engineering and management services to a wide variety of satisfied clients. During this time, Energypac has earned a reputation for stability and longevity .

THEIR VISION :

Energypac is a very well known name in the electrical power generation and distribution equipment market in Bangladesh. Since 1982 Energy Pac has already placed as number one choice for its products and service to the customers countrywide. Besides serving their existing customers in Bangladesh, They have extend their range of products and services to the largest range of products and services to the largest range power market in Government  or private owned utility enterprises and customers at home and abroad .

Their vision is to be leading electro-mechanical company in southeast Asia and put a solid footing in the export market by virtue of their continual development process, Their defecation to earn satisfaction of customers and their commitment to serve quality products and services.

PRODUCTS & SERVICES:

Energypac produce different types of electrical power generation and distribution equipment. The main products and service are…..

1. Transformer.2. AC/DC distribution boards/panel..3. ACB (Air circuit breakers).4. VCB (Vacuum circuit breaker).5. PFI (Power factor improvement).6. Relay panel.7. LT switchgear.8. HT switchgear.9. 11 KV load break switch.10. 33 KV control panel for in/out feeder.11. 11 KV incoming generator feeder-7(Generator BAY).12. Lightning Arrester.

Although we observe their production procedure…such as…

1. CNC machine.2. DIP-Pretreatment system.3. Insulation division.4. Assembly section.5. Seam welding machine.6. Testing area.

1.Transformer:

For the purpose of production & distribution there are two types of transformer..

1. Distribution transformer. 2. Power transformer.

1. Distribution transformer.Distribution  transformers  are  generally  used  in  electrical  power  distribution  and transmission systems.  This class of transformer has the highest power, or volt-ampere ratings, and the highest continuous  voltage  rating.    The  power  rating  is  normally determined  by  the  type  of  cooling methods the transformer may use.   Some commonly-used methods of cooling are by using oil or some other heat-conducting material.  Ampere rating is increased in a distribution transformer by increasing the size of the primary and secondary windings; voltage ratings are increased by increasing the voltage rating of the insulation used in making the transformer.Distribution transformer is used to convertelectrical energy of higher voltage (usually 11-22-33kV) to a lower voltage (250 or 433V) withfrequency identical before and after the transformation.

2. Power transformer: Power  transformers  are  used  in  electronic  circuits  and  come  in  many  different types  and applications.    Electronics  or  power  transformers  are  sometimes considered to  be  those  with ratings of 300 volt-amperes and below.  These transformers normally provide power to the power supply of an electronic device, such as in power amplifiers in audio receivers.

But for protection purpose there are another two types of transformer.1. Instrument potential transformer (PT)2. Instrument current transformer (CT)

1.Instrument Potential Transformer:

The instrument potential transformer (PT) steps down voltage of a circuit to a low value that can be effectively and safely used for operation of instruments such as ammeters, voltmeters, watt meters, and relays used for various protective purposes.

2.Instrument Current Transformer :

The instrument current transformer (CT) steps down the current of a circuit to a lower value and is used in the same types of equipment as a potential transformer.   This is done by constructing the secondary coil consisting of many turns of wire, around the primary coil, which contains only a few turns of wire. In this manner, measurements of high values of current can be obtained. A current transformer should always be short-circuited when not connected to an external load. Because the magnetic circuit of a current transformer is designed for low magnetizing current when  under  load,  this  large increase  in  magnetizing  current  will  build  up  a  large  flux  in  the magnetic  circuit and  cause  the  transformer  to  act  as  a  step-up  transformer,  inducing  an excessively high voltage in the secondary when under no load.

2. AC/DC distribution boards/ panel:

AC/DC Distribution Boards: The distribution board shall be self standing sheetsteel cubicle, single front construction front wired and front connected andsuitable for mounting against the building wall. The AC distribution board shallbe designed for operation at 415 V + 10%, 3 Phase, 4 wire, 50 Hz, solidlygrounded system. The DC distribution board shall be suitable for operation at110V + 10% unearthed system.The main buses and connections shall be of high conductivity aluminum/aluminium alloy sized for specified current rating. Maximum temperature of thebus limited to 85 deg. C. All the bus bars shall be provided with heat shrunkinsulating sleeves with suitable phase identification marking. The bus bar supportshall be flame retardant track resistant type with high creep age surface. Theswitches and fuse units shall have a quick make and quick break mechanismoperated by a suitable external handle complete with on/off position indicator.The fuses shall be HRC link type with the fuse base and fittings of such design asto permit easy replacement of fuse element. The outgoing switch fuse feeder shallbe provided with current transformer for metering purpose. The currenttransformer shall be cast resin type of class 10P10 for protection and class 1ISFless than 5 for metering. The wiring shall be done with flexible 650 grade PVCinsulated with stranded copper conductor of 2.5 mm2 for control and currentcircuit and 1.5mm2 for voltage circuit. All power and control cables shall enterthe DBs from top of the panel, cable support and removable type gland plate atleast 4 mm thick shall be provided. A galvanized steel ground bus rated to carrymaximum fault current shall be furnished along the full length of ACDB/DCDB.

3. ACB (Air circuit breakers):

Figure: ACB

Air circuit breakers can be used both as circuit-breakers for general protection (of plants, of user complexes, of electric lines) and as protection circuit breakers of electrical machines (generators, motors, transformers, capacitors).

These can be used both as circuit-breakers for general protection (of plants, of user complexes, of electric lines) and as protection circuit-breakers of electrical machines

(generators, motors, transformers, capacitors). They are used in all types of plants (civil, industrial, and in the service sector) as well as in the equipment on-board ships, in mines, in prefabricated substations, and for primary and secondary distribution in general.

4. VCB (Vacuum circuit breakers):

Figure: VCB

The Vacuum Circuit Breaker is designed to protectively disrupt an electrical circuit upon signal. The breaker may also be closed by operating the switch handle. It may be opened manually or electrically by optional under voltage and/or shunt trip devices. The standard visible disconnect is a visual means of circuit interruption and also a means of grounding the output terminals. The Vacuum Circuit Breaker closes into a load versus the Vacuum Load Breaker which breaks a load.

5. PFI (Power factor improvement):

Motor, Transformers and other inductive loads require reactive power. PFI Plant is used to improve the power factor of the inductive loads in the electrical network by Capacitor Banks. The capacitors are of low losses and with inbuilt discharge resistor. The use of appropriate rating of PFI Plant reduces undesirable wastage of power.

Figure: PFI(power factor improvement)

All control & indicating devices are located on the front door of the panel for easy viewing by the operator.

Why do I need Power factor correction?

Capacitive Power Factor correction (PFC) is applied to electric circuits as a means of minimising the inductive component of the current and thereby reducing the losses in the supply. The introduction of Power Factor Correction capacitors is a widely recognised method of reducing an electrical load, thus minimising wasted energy and hence improving the efficiency of a plant and reducing the electricity bill.It is not usually necessary to reach unity, ie Power Factor 1, since most supply companies are happy with a PF of 0.95 to 0.98.

6. Relay panel:

Figure: Relay panel

A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism, but other operating principles are also used. Relays find applications where it is necessary to control a circuit by a low-power signal, or where several circuits must be controlled by one signal. A type of relay that can handle the high power required to directly drive an electric motor is called a contactor.Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload or faults; in modern electric power systems these functions are performed by digital instruments still called "protection relays".

There are different types of relay, we only see here Buchholz relay.

Buchholz relay:

A Buchholz relay is a safety device sensing the accumulation of gas in large oil-filled transformers, which will alarm on slow accumulation of gas or shut down the transformer if gas is produced rapidly in the transformer oil.

7. LT (LOW TENSION) SWITCHGEAR:

Sheet steel cladded with modular systems for assembly of cubicles intended to take heavy equipments, dust and vermin proof, free standing, floor mounting indoor/outdoor type with heat proof, powder coated painting, with TPN & E copper bus bar. It is equipped with different type of Circuit Breakers such as Air Circuit Breaker (ACB), Molded Case Circuit Breaker (MCCB), Miniature Circuit Breaker (MCB), Motor Control Circuit Breaker etc., relay, Control & indicating. All control and indicating devices are located of the front of upper low voltage compartment for easy checking by the operator.

8. HT (HIGH TENSION) SWITCHGEAR:

Sheet Steel Clad, dust and vermin proof, free-standing, floor-mounting & indoor/outdoor type, completely factory assembled with heat proof, powder coated painting, HT Switchgears are designed with VCB (Vacuum Circuit Breaker)/LBS (Load Break Switch)/Minimum Oil Circuit Breaker (MOCB)/Hexa-Fluoride (SF6) Circuit Breaker, Voltage Transformer and Current Transformer with metering and protection panel as to IEC.All control and indicating devices are located of the front of upper low voltage compartment for easy checking by the operator.

9. 11 KV load break switch:

Energypac has developed an 11 kv three-pole load break switch which can be applied in unitised substations, for transformer control, switching of cables, overhead lines, etc. These load break switches have special features of arc quenching by puffer action and manual and fuse blown tripping facility. The scattering of arc is prevented retaining insulation level and prevents flashover during tripping operation. The switch incorporate a high speed make and break mechanism, ht hrc fuse and is also provided with an earthing switch interlocking with main mechanism. The lbs cannot be operated when earthing switch is on and vice versa. The company is also provided with optional auxiliary switch and shunt release. These load break switch is rated for 11 kv, 630 a and 26.3 ka/1 sec.Short time current.

10. 33 KV control panel for in/out feeder:

Figure: 33 KV control panel for in/out feeder

These 33 kv controal panels are manufactured by Energypac using state-of-the-art technology and advanced machines.

These are widely used for:

Protection and Control for Transformers. Protection and Control for Transmission and distribution lines. Protection and Control for Bus Section and Bus Coupler.

11. 11 KV incoming generator feeder-7(Generator BAY):

figure : 11 KV incoming generator feeder-7

The switchgear has two incoming lines equipped with VCB's and one bus-coupler. The incoming VCB's will be N.C and the bus-coupler will be N.C in normal operation. In the absence of voltage on any incoming the dead incoming VCB will be switch-off and the bus-coupler VCB Will be switched-on automatically. By voltage restoration the returnwill be done manually not automatically. There is not any 11kV motor as outgoing feeder, only 11KVtransformers and downstream switchgears exist as outgoing.

12. Lightning Arrester:

Figure: Different types of lightning arrester.

A lightning arrester is a device used on electrical power systems to protect the insulation on the system from the damaging effect of lightning. Metal oxide varistors (MOVs) have been used for power system protection since the mid 1970s. The typical lightning arrester also known as surge arrester has a high voltage terminal and a ground terminal. When a lightning surge or switching surge travels down the power system to the arrester, the current from the surge is diverted around the protected insulation in most cases to earth.

So we can say that lightning arrester is a protective device for electrical equipment that reduces excessive voltage resulting from lightning to a safe level by grounding the discharge.

Types of lightning arrester:

There are several types of lightning arrester in general use. These differ in constructional details but operate on the same principle.

Different types of lightning arrester are as followed:

Rod gap arrester. Air gap arrester. Horn gap arrester. Multigap arrester. Expulsion type lightning arrester. Valve type lightning arrester.

Now I explain some production procedure what we have seen in Energypac study tour.

1. CNC machine.

2. DIP-Pretreatment system.3. Insulation division.4. Assembly section.5. Testing area.

1. CNC machine:

Figure: CNC machine.

In modern CNC systems, end-to-end component design is highly automated using CAD/CAM programs. The programs produce a computer file that is interpreted to extract the commands needed to operate a particular machine, and then loaded into the CNC machines for production. Since any particular component might require the use of a number of different tools—drills, saws, etc.—modern machines often combine multiple tools into a single "cell". In other cases, a number of different machines are used with an external controller and human or robotic operators that move the component from machine to machine. In either case, the complex series of steps needed to produce any part is highly automated and produces a part that closely matches the original CAD design.

2. DIP-Pretreatment system:

DIP-pretreatment system is use to prepare the iron sheet for the production of different electrical equipment.

3. Insulation division:

Figure: Insulation division.

In insulation division CT,PT core & different types of insulation procedure are completed.

4. Assembly section:

Figure: Assembly section

In assembly section different types of transformer are finally produce.

5. Testing area:

In this area transformer are tested so is they are able to work properly at high voltage.

DISCUSSION:

In this high voltage Engineering lab tour in energypac, we can clearly observe different types of electrical device such as_ different types of protective device, transformer etc. But when we read it in our text book we can not clear It .If our university take this type of industrial study tour then it will be most effective as an engineer student. Finally, I can say so proudly that this tour is a great achievement in my engineering student life.

Prepared by:Dipok Chandra pal.Department of Electrical & Electronics Engineering (EEE)Stamford University, Bangladesh.Email: dipok_pal@yahoo.comWeb: www.dipok.weebly.comMobile: +8801913086360Date: 14/06/2010

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