Electrical System Design

Scope

This course is meant for Fresh Graduates/ Diploma holders and persons with experience in fields like sales, maintenance, Construction who would like to change their career line to challenging project design – from concept to commissioning. Engineering has a role to play in almost all the sectors of industry. Engineering is the most important determinant in shaping a career and demand for qualified engineers in all sectors of the worldwide industry. With the advancement in science and technology, new processes have developed. Corresponding plants are being set up. Hence there has been & there will be a tremendous increase in the scope of engineering. In order to utilize the opportunity, everyone has to be prepared himself to face the challenges. To meet industrial requirements of skilled manpower in specialized fields of engineering Suvidya Institute of Technology has come up with a detailed Curriculum of the Engineering of projects Electrical system.

The faculty is drawn senior members of Industry and consultants. They have vast experience in the field of engineering/ maintenance/ construction and commissioning/ inspection and training the engineers in the art of electrical project design. They, therefore, interpose the theoretical with practical aspects of engineering.

The course combines sound engineering principles, applicable codes, and best industrial practices. Institute is also encouraging to develop rational thinking skills through case study and application of root cause analysis in any problem solving. Successful completion of these courses will help the students in gaining confidence for being employable in a wide range of industries. To name a few:

• Operation of Electrical systems
• Technical sale of project electrical equipment
• Commercial and Residential Projects
• Petrochemicals
• Refineries
• Metallurgical
• Cement
• Pharmaceutical
• In short any industry you name you are needed

The Curriculum --- The Course deals with Power distribution system with various alternatives - Selection, Specification & procurement of electrical equipment - Substation Design with or without Trench - Automation in Equipment control. The subjects are detailed with reference to the following:

• Overview of industry and their requirement of electrical systems.
• Role, Importance, Responsibility of Electrical Engineer.
• Client requirements & collection of specific data for projects.
• Use of International Standards, Design Basis, std. practices/procedure and specifications.
• Understanding Basic Design requirement based on the type of various plants.
• Intra-discipline co-ordination with civil, process, mechanical, piping, telecom HVAC etc…
• Cable System Design.
• Introduction to Heat Tracing systems and cathodic protection.
• Design system for Power distribution, Earthings, Lightning and lightning protection.
• Vendor drawing review and approval – typical transformer.
• Introduction to Inspection of Equipments. Inspection methodology discussed for getting right inspection done. Practical inspection cases presented.

Engineering of various types of Projects The Participants are introduced to various aspects of Engineering of Electricals of projects, the role played by electrical engineer in user-friendly design of projects from concept to commissioning. What information, from whom information has to come & to whom electrical information has to go is well coordinated in this module to get a project design with almost no hiccups at execution & commissioning stage.

Key Processes in Electrical Project Design

The Various processes like extended basic engineering, Procurement of Electrical Equipments, Substation Design, overall cable Tray Layout plot, Power/ Lighting/ Earthing layout of each section of plant are detailed.

Key single line diagram

This document is the key document developed for each project. This has all the aspects which we have considered for smooth operation of the entire plant This is the starting point of the project -- final record of the design carried out -- basis of procurement – should main bus and emergency bus be separate OR common -- selection of feeding switch board based on equipment location in the plant – Lighting board location in the plant OR in substation – up to what level of distribution voltage the key sld is developed sand why -- Lighting transformer purpose -- Dual feed – auto transfer – loads off – electrical responsibility -- Dual feed – transfer on load – momentary – how done – check synchronizing relay -- Forward synchronizing – reverse synchronizing -- Castel & electrical interlock – standard voltage for motors – system –

User list - Load list -----

This is a list through which project/ process department communicates to other departments & clients the various equipments both static & rotary, the specifications with respects to their operating temperature, pressure etc. As electrical engineer we are interested in absorbed power, method of control of motor & which equipments have to be addressed with respect to power fluctuations. All these are communicated through various fields in the user list. This list forms basic for the control design & thus directly to procurement of other electrical equipments like HV/ PCC/ MCC/ LCS etc. Each & every field is explained with respect to application in engineering.

Short Circuit understanding -----

Within this module the system fault level depends on various sources of generation of power inclusive of high inertia drives where motor generates power after disconnection due to the inertia of driven equipment. How the various reactance dictate the different levels of short circuit for selection equipments is dealt.

• Short circuit ---critical for the entire system.
• Why does Short circuit current, remains very high for initially few cycles and gradually decreases and finally gets into steady state mode.
• Three types of reactance ----- Sub transient reactance X’’d /Transient reactance X’d / Synchronous reactance Xd--- how long the sub transient/ transient and steady state current lasts.
• What is the current and time the CB and the board are to withstand --- what is interrupting duty expected ---can the withstanding capacity be lower than interrupting capacity etc.
• What is the meaning of high, low X/R ratio.
• CB generally opens (fault clearing time) in 8 cycles.
• Role of motors in fault contribution.

Electrical Equipments -----

Understanding the why of the specifications from construction point of view, safety & operational ease of various electrical equipments for a project. All the electrical equipments of the project are covered in detail during the course The equipments covered are

• A.2 HT SWITCHBOARD
• A.3 TRANSFORMER
• A.4 LT SWITCHBOARD
• A.5 CABLES
• A.6 BUS-DUCT
• A.7 MOTORS
• A.8 LOCAL CONTROL STATION
• A.9 DISTRIBUTION BOARD
• A.10 LIGHT FITTINGS
• A.11 DG SET
• A.12 TG SET
• A.13 BATTERY CHARGER
• A.14 CAPACITORS & ITS CONTROL PANEL
• A.15 NEUTRAL GROUNDING RESISTOR
• A.16 VFD
• A.17 UPS
• A.18 HEAT TRACING
• A.19 CATHODIC PROTECTION
• A.20 CONTROL PANELS / STARTER PANELS
• A.21 CONSTRUCTION POWER
• A.22 INSTALLATION

HV Switchgear -----

• • The typical values of short circuit ratings / current ratings for Busbars / Standard voltage ratings of HV switchgear for Industrial premises as per applicable standard – type of CB – what is SF6 – vacuum dielectric – Fuse contactor units – configurations alternatives – components that make a HV switchgear – list of type and routine tests . The various compartments are discussed.

• • Withdrawable vacuum circuit-breaker panel (with switchgear truck withdrawn and partition removed)

• 1. Panel ventilation (forced ventilation)
  2. Low-voltage compartment
  3. Connecting cables to low-voltage lug connector
  4. Withdrawable vacuum circuit-breaker
  5. Truck
  6. Wipers of withdrawable section
  7. Cover (stainless steel) to cable connection compartment (tool required to open)
  8. Ventilation flap
  9. Busbars
  10. Metal shutters (internal protection against solid foreign bodies and touch) made of stainless steel
  11. 4MB bushing-type current transformer
  12. Bar connection
  13. Make-proof earthing switch

• • Interlocks
  • Interlocks to prevent:
    • "Plugging in" of a closed breaker.
    • "Plugging in" a breaker with earthing isolator closed.
    • "Closing" of the earthing isolator with breaker "plugged in".
    • Pulling out the auxiliary circuit plug with breaker in the service position.
    • "Closing" of the earthing isolator with breaker "plugged in".
    • Pushing in the breaker to the service position, with auxiliary circuit plug not in position.
    • Earthing switch closing with CB in connected/intermediate position.

  Doors of withdrawable units with interlock systems to avoid:

  • Opening of compartment door when withdrawable unit is in connected/intermediate position.
  • Racking of withdrawable unit when compartment door is open.

  Transformer---

  • Tank – construction -- Base -- Reinforced to prevent distortion. Base channel – with rollers and pulling eyes - why.
  • Radiators – Detachable with shut off valves, air vent, drain, lifting lugs. Can be fixed for less than 500 kVA.
  • Why nonmagnetic gland plate.
  • Head room for termination inspection.
  • HV fault withstand time – 0.2” – why wrt sec fault discuss -- LT & HT withstand relation -- Talk about loading vs Fault level.
  • Why tap changers -- From which windings taken and why -- What is the meaning of +- Tap position.
  • What happens in terms of transformer operation wrt + or – tap -- Why called OCTC & not NLTC.
  • OLTC located where and why.
  • What is trafo capacity loss due to regulation. Purpose of conservator -- Oil resistance air bag – physical trafo mounted protections -- accessories.

  PCC and MCC---

  Low voltage switchgear is a system of standard sections -- Vertical panels of uniform height.-Discuss applicability, advantage & disadvantage -- Main Bus Bar -- The hot spot temperature 95°C---?? Auxiliary Interposing relay or terminal compartment alternatives ???? -- Sized for receiving specified number of cables -- three positions for the draw out trolley --Switchgear Components Power cum Motor Control Center -- what is PCC ????, MCC -- Can we equate this to high voltage board --what are panel sections --what is draw out etc. who prefers and why -- Control trafo module Minimum 2000 VA control transformer -- CB modules /SFU modules / Aux terminal module Switches / Fuses/Contactors/Thermal Overload Relay What is then diff between PMCC and MCC
  

  Cables---

  Why do we need cable? Types of cables -- what you mean by 3.3/6.6 kV : 6.6/6.6 kV : 6.6/11 kV: 11/11 kV – where are screens used -- core configurations – construction of HV and LV cable -- conductor types – temp withstand of insulations – laying conditions – derating factors applicable – bending radius -- points to be considered when selecting cables -- LV cable and hv cable main criteria
  

  Bus Duct---

  What is Busduct – HV – LV – phase segregated -- expansion joints at suitable intervals – wall frame assembly – different adopter chambers – care in specs for no problem installation – why phase cross over chambers
  

  Motors---

  • Motor application for various duties, different motor parts particularly terminal boxes. Alignment facilities to be specified work horse. Why DOL preferred. Number of starts per hour and why. Bidirectional vs. unidirectional. Problems if wrong direction specified. Turn down tank for lubrication. Motor class F with permissible rise as per class B. Where are terminal boxes located. Phase segregated terminal boxes. Fans. Lifting hook. Temperature detectors. Polarisation index. How terminal boxes in HT can be rotatable like LT motors.
  • Local Control Station---
  • Why local control station. How many types. What use "NO" contact of STOP Actuator. Ambient temperature effect. Why specify additional cable entry. Why 2 additional terminals. Effect of extreme temperatures on MOC of LCS.
  • Lighting DB---Configuration available should there be a lighting transformer. What is the criteria for max Lighting transformer capacity. Can't we design lighting system without lighting transformer. Limiting size of fuse in feeder.
  Lighting--- A good lighting is an aid to productivity & comfort feeling. The lighting system like functional lighting for plant, overall lighting for safety, escape route lighting, work station lighting without glare are addressed. Main point emphasized aesthetics with ease of maintenance, fault finding & isolation of defective lights in minimal time, retaining balance light for operation-coordinating with Civil, Architectural, HVAC group for lighting system & Supports for “no clash”. Developing standard installation drawings. Point by Point and coefficient method of lighting design is discussed
  • Diesel Generator Set -----
  Why DG sets- if required what capacity- input from where – when VD is high how solve – starting sequences - layout considerations POWER GENERATION SYSTEMS -- Prime Mover/Generator -- Generator & AVR -- Generator Excitation Control Systems -- Generator Protection -- Generator Synchronisation – main task of AVR – how to read droop characteristics and analyse generator operation – synchro methods -- jacking oil
  • Battery and chargers -----
  Battery classification-Types- applications – duties – types – vented vs valve regulated – allowed Hydrogen concentration -- Battery Room ventilation requirements – sizing fundamentals – typical load profile – Charger requirements
  • Power factor Correction -----

  Sizing Capacitor Banks:

  • Calculate total kW demand and power factor on each switchboard-(Refer to the load list for each switchboard)
  • Determine the value of the power factor to be improved (power factor shall generally be higher than 0.9 lag and below unity )
  • Packages -----
  • Why package specs – how to prepare them for no hiccup execution – should it be a diluted version – format for package scope – minutes of meeting etc
  • Uninterruptable Power Supply (UPS) -----
  What is UPS- where used- alternatives-abnormalities in Grid- UPS Configurations – Battery Sizing
  • Operation Modes:
  • Variable Speed drive -----

  Introduction --

  What Is a Variable Frequency Drive? How Does a VFD Work Types of Drives - DC & AC -- ‘Types of AC Drives’ -- ‘System Components of A.C. Drives’ -- Effects Of Drives On Electrical System Application –benefits of VFD – how much savings -- magnetic amplifier application
  • Schemes -----
  The DOL Scheme for HV developed from components specified, developing block components for a scheme, LV scheme, Interconnection drg for a typical scheme
  • Earthing -----
  • Purpose of earthing -- classification of earthing --concept of earthing -- applicable standards -- quantities of good earthing --factors affecting the earthing resistance -- different types of earthing electrode -- calculating resistance of baried earthing strip -- inputs required for earthing calculation -- . calculation of no. of earthing electrode factors effect on ground resistance
  • Hazardous area Classification -----
  • What is area classification -- why has this to be identifies -- methods of classification -- How to avoid explosion – use of fire tringle in practical situations- types of hazardous area equipment & applications – auto ignition temperature -- MEAG & max flame path- certification understand -- IIC and IIA/B area and equipments differences – Dust Hazard
  • Substation -----
  • Nerve centre of power – what is it – reliability – as per of substation design – Receive – Distribute – Protect – Meter – Monitor – Cont –Segregation -- Installation ease -- Ease of maintenance -- Handle emergencies -- Future expansion -- Replace any equipment in future – who are involved – what erupts to be accommodated -- space allotment for others - clearances – column spacing your priority
  • Power Lighting Earthing layouts -----
  • How to prepare – how to coordinate – generate weld able surface on concrete – construction friendly design for short execution time – Various methods of cable engineering
  • Light fitting installation standards
  • lightning protection – coordinate with Civil for conductor fixing on sheets of warehouse
  • Earth pits and interconnections – Earth bus – Earthing conductor
  • Protection -----
  Protective relays general – Introduction / operation principle / terminology of protective relaly / types of relays / instantaneous overcurrent relay / definite time over current relay inverse time overcurrent relay / directional over current relay Motor protection requirements - abnormal motor operating conditions. …..Prolonged starting / locked rotor condition -- Failure of / inadequate ventilation --Bearing failure -- overloads -- Frequent starting / jogging - Single phasing -- Inverted phase sequence -- Under voltages / Over voltages -- Under frequencies / over frequencies -- Surge voltages -- Internal faults within the motor -- Earth faults
  • Calculations -----
  Transformer Sizing -- Cable Sizing -- Lightning Protection -- Earthing Design Board Sizing -- Lighting Design --DG Sizing – Approach to battery sizing
  • Cathodic Protection & Heat tracing -----
  • Cathodic protection
  1. Stray direct current corrosion
  2. Bi-metallic corrosion
  3. Galvanic corrosion of a single metal
  4. Cathodic protection
  5. Methods of applications
  6. Selection of CP
  • Heat Tracing
  1. Types of heat tracing system
  2. Overview of heat tracing system
  3. Selection and sizing of appropiate heat tracer
  4. Codes, approvals and standard
  • Document list -----
  • Details all the documents generated by electricals – its input source - output sent to whom & why – specification list – calculations list – various schedules – standard drawings – P/L/E layouts – inter conn schedule are all addressed
  • Tutorials – assignments – unit test- final exam ----
  During the training the students are given assignments & tutorial work. These are followed by Weekly Assessments & final exam. The number of assignments will be at discretion of the faculty based on participants. The duration of Weekly Assessment & final exam are 2 & 3 hours respectively. These will be increased suitably based on participant’s enthusiasm, interest. These tests are designed to increase confidence of the participants by exposing them to variety of questions.
  • Data sheets ----

  The data sheets form integral part of any equipment – Typical HV board, Transformer and MCC discussed

  
  

  Site Visit will be arranged at industrial plant either in shut down or not working conditions.