Schneider Electric Cahiers Techniques

Schneider Electric Cahiers Techniques – A collection of documents intended for engineers and technicians

Cahiers Techniques is a collection of documents intended for engineers and technicians, people in the industry who are looking for more in-depth information in order to complement that given in product catalogues. Furthermore, “Cahiers Techniques” are often considered as helpful “tools” for training courses.

Schneider Electric provides knowledge on new technical and technological developments in the electrotechnical field and electronics. They also provide better understanding of various phenomena observed in electrical installations, systems and equipment.

Each “Cahier Technique” provides an in-depth study of a precise subject in the fields of electrical networks, protection devices, monitoring and control and industrial automation systems.

About Schneider Electric

Schneider Electric SA. The Group’s principal activities are electricity and automation management. The Group operates under three major segments:

• Electrical distribution
• Automation and Control
• Secured energy

Energy and Automation

Introduction, Motors and Control

Siemens A.G. is Europe’s largest electrical and electronics company, producing over 50,000 products manufactured at 400 sites in 40 countries.

Referring to the Siemens history of achieving success through well engineered refinements of other people’s inventions, one Fortune analyst noted that “second is best” might well serve as Siemens’ motto. But opportunism is not the only interesting facet of Siemens’ history, which is also a story of a long family tradition and intimate involvement with some of the most important events of the 19th and 20th centuries.

Siemens and Halske was founded in Berlin in 1847 by Werner Siemens and J. G. Halske to manufacture and install telegraphic systems. Siemens, a former artillery officer in the Prussian army and an engineer who already owned a profitable patent for electroplating, was the driving force behind the company and remained so for the rest of his life.

The company received its first major commission in 1848, when it contracted to build a telegraph link between Berlin and Frankfurt.

Beside some very good books and guides, Siemens as one of the world leader in industry and automation, has released and this 18 books ‘Basics of energy and automation’ related to electricity in general, motors and control, power distribution etc.

All documents, EE software and EE books are free to Download

No.	Basics of Energy and Automation: Introduction, Motors & Control	Download
1	Basics of Electricity
2	Basics of Electrical Products
3	Basics of AC Drives
4	Basics of AC Motors

Power Substation Guides

Electricity generation

An electrical substation is a subsidiary station of an electricity generation, transmissionand distribution system where voltage is transformed from high to low or the reverse using transformers. Electric power may flow through several substations between generating plant and consumer, and may be changed in voltage in several steps.

A substation that has a step-up transformer increases the voltage while decreasing the current, while a step-down transformer decreases the voltage while increasing the current for domestic and commercial distribution. The word substation comes from the days before thedistribution system became a grid.

The first substations were connected to only one power station where the generator was housed, and were subsidiaries of that power station.

Equipment in substation

Substations generally have switching, protection and control equipment and one or more transformers. In a large substation, circuit breakers are used to interrupt any short-circuits or overload currents that may occur on the network. Smaller distribution stations may use recloser circuit breakers or fuses for protection of distribution circuits. Substations do not usually have generators, although a power plant may have a substation nearby.

Other devices such as power factor correction capacitors and voltage regulators may also be located at a substation.

Substations may be on the surface in fenced enclosures, underground, or located in special-purpose buildings.

High-rise buildings may have several indoor substations. Indoor substations are usually found in urban areas to reduce the noise from the transformers, for reasons of appearance, or to protect switchgear from extreme climate or pollution conditions.

Where a substation has a metallic fence, it must be properly grounded (UK: earthed) to protect people from high voltages that may occur during a fault in the network. Earth faults at a substation can cause a ground potential rise. Currents flowing in the Earth’s surface during a fault can cause metal objects to have a significantly different voltage than the ground under a person’s feet; this touch potential presents a hazard of electrocution.

All documents, EE software and EE books are free to download.

Guides

No.	Description	Download
1	Answering Substation Automation Questions Through Fault Tree Analysis
2	Applying an Ethernet LAN in a Substation
3	Power Plant Accoustic
4	Power Transformer Maintenance And Acceptance Testing
5	Selecting Energy Efficient Distribution Transformers

Electrical Engineering Guides

Nikola tesla - Serbian-American inventor, mechanical engineer, and electrical engineer.

Electrical engineering is a field of engineering  that generally deals with the study and application of electricity, electronics  and electromagnetism. Companies and industry experts has been always releasing technical books and guides in order to spread their knowledge.

On this page you can find very usefull books and guides related to electrical science industry, automation and telecommunications.

All documents, EE software and EE books are free to download.

Electrical books and guides

No.	Description	Download
***	Schneider Electric – Cahier Techniques – FOLDER
***	ABB Drives – Technical Guides – FOLDER
***	Siemens – Basics of Energy and Automation – FOLDER
***	Relays In Details (Including Protective Relays) – FOLDER
***	Power Substations – FOLDER
1	Electrical power supply and distribution
2	Energy-Efficient Electric Motor Selection Handbook
3	Coordinated Power Systems Protection
4	UPS selection, installation and maintenance
5	Engineering Symbology, prints and drawing

Electrical MS Excel Spreadsheets

Electrical Tools - MS Excel Spreadsheets

Electrical tools (MS Excel Spreadsheets)

This section is dedicated to tools every electrical engineer can use in daily work. These spreadsheets below will make your job much more easier, alowing you to shorten the time used for endless calculations of cables, voltage drop, various selctions of circuit breakers, capacitors, cable size and so on.

Most of spreadsheets are developed by two electrical engineers and programmers mr. Jignesh Parmar and mr. Hemant Kashikar. They all really did an awsome job, you must admit.

Location of Current Transformers in HV Substation

Siemens High Voltage Instrument Transformers

Power flow

Current transformers are used for protection, instrumentation, metering and control. It is only the first function that has any bearing on the location of the current transformer.

Ideally the current transformers should be on the power source side of the circuit breaker that is tripped by the protection so that the circuit breaker is included in the protective zone.

In many circuits the power flow can be in either direction and it then becomes necessary to decide which location of fault is most important or likely and to locate the current transformers on the side of the circuit breaker remote from those faults. In the case of generator (and some transformer) circuits it is necessary to decide whether the protection is to protect against for faults in the generator or to protect the generator against system faults.

Current transformers can often be located in the generator phase connections at the neutral end and will then protect the generator from the system faults and to a large degree give protection for faults in the generator.

When current transformers can be accommodated within the circuit breaker, they can in most cases be accommodated on both sides of the circuit breaker and the allocation of the current transformers should give the desired overlapping of protective zones.

Short To Full name

Short To Full name

Abbreviation           Expansion
ACDB                                                 Alternate Current Distribution Box
AMF                                                   Auto Mains Failure
AQA                                                   American Quality Assessors
AVM pads                                          Anti Vibration Mould pads
AGL                                                   Above Ground Level
BB                                                      Battery Bank
BIS                                                     Bureau Of Indian Standards
BOM                                                  Bill Of Material
BTS                                                    Base Trans Receiver Station
BV & DV                                           Build Vendor & Delivery Vendors
CELL Site                                          Composition Of Tower, DG and Shelter
CDMA                                               Code Division Multiple Access
CPRI                                                  Centre Of Power Research Institute
CT & PT                                            Current & Potential Transformer
CVCL                                                Certificate Generator Set
DG Set                                               Diesel Generator Set
Day Markings                                     Orange & White pint bands on tower
DPR                                                   Daily Progressive Report
EAT                                                   Electrical Acceptance Testing
EGB                                                   External Grounding Bus Bar
FA                                                      Final Acceptance
FCU                                                   Fan Control Unit
FS                                                      Foll Scope
FTA                                                   First Time Acceptance
GBT                                                   Ground Base Tower
GI                                                      Galvanized Iron
GSM                                                  Globar System Mobilization
ICAO                                                 International Code Of Aviation Organization
IGB                                                    Internal Grounding Bus Bar
ISO                                                    International Organization Of Stanards
ISO-9001 & 14001                            9001 represents Quality & 14001 Environment
ISMB                                                 I Section Medium Beam
MCB                                                  Miniature Circut Board
MHz                                                   Mega Hertz
MIS                                                    Management Information System
MW Antenna                                      Micro Wave Antenna
NGL                                                   Normal Ground Level
Night Beacom                                     Aviation Lamp
OFC                                                   Optical Fibre Cable
O & M                                               Operations & Maintenance
O & E M                                           Operations & Equipment Mainenance
OPC                                                  Ordinary Portland Cement
PABX                                                Public Automatic Branch Exchange
PCB                                                   Printed Circuit Board
PCC                                                   Plain Cement Concrete
PCM                                                  Phase Change Material
PIU                                                    Power Interface Unit
PM                                                    Project Management
PMC                                                 Project Management Consultancy/ Company
PPC                                                  Pozzalana Portland Cement
RC                                                    Rate Contract
RCC                                                 Reinforce Cement Concrete

Selection Of Number Of Cable Cores With Emphasis On Sizing Parameters

Selection Of Number Of Cable Cores With Emphasis On Sizing Parameters (photo by dnvkema.com)

Dependance On Installation Site

The selection of number of cable cores basically depends on the type of system where it is going to be installed.

Generally we have two types of systems:

1. A perfectly balanced system and
2. A system with some degree of unbalance (or Unbalanced System).

Generally cable sizing includes below parameters:

1. Cable installation conditions and the load it will carry
2. Continuous current rating of the cable
3. Voltage drop and short circuit considerations
4. Earth fault loop impedance

Here, I am going to describe that how the number of cores can be selected.

3-Core Cables

These cables are used generally for a perfect balanced 3-phase system. When the currents on the 3-live wires of a 3-phase system are equal and at an exact 120° phase angle, then the system is said to be balanced. The 3-phase loads are identical in all respects with no need of aneutral conductor.

An important example of 3-phase load is electric motor and that is why, they are fed through 3-Core cables in most cases.

3.5-Core Cables

A 3-phase system may have a neutral wire. This wire allows the 3-phase system to be used athigher voltages while it will still support lower voltage single phase loads.

It is not likely in such cases that the loads will be identical, so the neutral will carry the out-of-balance current of the system. The greater the degree of imbalance, the larger the neutral current.

3-5-core cable construction (figure by mitesh-raval.blogspot.com)

When there is some degree of unbalance and the amount of fault current is very small, then 3.5 core cables are used. In these types of cables, a neutral of reduced cross section as compared to the 3-main conductors is used, which is used to carry the small amount of unbalanced currents.

4-Core Cables

When there is severe out-of-balance conditions, the amount of fault current will raise to a very high level. Generally in the case of linear loads, the neutral only carries the current due to imbalance between the phases.

4-core PVC insulated and sheathed copper conductor power cable

The non-linear loads such as switch-mode power supplies, computers, office equipment, lamp ballasts and transformers on low loads produce third order harmonic currents (Definition of Harmonics and Their Origin) which are in the phase of all the supply phases.

These currents do not cancel at the star point of a three-phase system as do normal frequency currents, but add up, so that the neutral carries very heavy third harmonic currents.

That is why the neutral of the cable feeding the equipment are not reduced and made with cross sectional area same as that of the main conductor to carry this high amount of current.

5 and 6-Core Cables

Some conditions may arrive when the amount of fault (neutral) current becomes very large than the phase currents. When the load concerned to this type of situation is fed through a multi-core cable, it is necessary to use a 5-Core or 6-Core Cable.

5-core PVC insulated and sheathed copper conductor power cable

In this condition, two (or three) conductors can be used in parallel formation to carry the high amount of generated unbalanced currents.