Megger Tests

The insulation resistance meter test method for determining the condition of electrical insulation has been widely used for many years as a general nondestructive test method.

A serious limitation of this test is that its operating voltage of 500 to 1,000 volts will not always detect insulation punctures, whereas the higher voltages used by the high-voltage, DC testers will detect these punctures.

The insulation resistance meter test will show following parameters:

(a) Relative amount of moisture in the insulation,
(b) Leakage current over dirty or moist surfaces of the insulation, and
(c) Winding deterioration or faults by means of insulation resistance versus time curves.

Description of Test

How To Use A Digital Multimeter

A digital multimeter is used to make various electrical measurements, such as AC and DC voltage, AC and DC current, and resistance. It is called a multimeter because it combines the functions of a voltmeter, ammeter, and ohmmeter.
Multimeters may also have other functions, such as diode and continuity tests.

What is HIPOT Testing (Dielectric Strength Test)?

Hipot Test is short name of high potential (high voltage) Test and it is also known as Dielectric Withstand Test. A hipot test checks for “good isolation.”
Hipot test makes surety of no current will flow from one point to another point.
Hipot test is the opposite of a continuity test.
Continuity Test checks surety of current flows easily from one point to another point while Hipot Test checks surety of current would not flow from one point to another point (and turn up the voltage really high just to make sure no current will flow).

Importance of HIPOT Testing

The hipot test is a nondestructive test that determines the adequacy of electrical insulation for the normally occurring over voltage transient. This is a high-voltage test that is applied to all devices for a specific time in order to ensure that the insulation is not marginal.

Basic-Stand-Alone-Application-of-Reclosers

Overcurrent protection

Reclosers are self-contained fault interrupting and reclosing devices, specifically designed for overcurrent protection in secondary distribution systems.
Reclosers are situated in selected locations within the overhead distribution network. With the correct protection setting and MV fuse selection coordination, concerning the whole supply loop from the supplying primary distribution substation feeder to the fuse-protected distribution transformer, it is possible to achieve a discriminative fault isolation function.

Traditionally, the recloser units do not have any remote communication facilities. To enhance the system monitoring and restoration facilities, the reclosers can be equipped with remote communicating protection and control units.

ABB – Electrical Installation Handbook PART I

Scope and objectives                         

Download:

Right here

The scope of this electrical installation handbook is to provide the designer and user of electrical plants with a quick reference, immediate-use working tool.
This is not intended to be a theoretical document, nor a technical catalogue, but, in addition to the latter, aims to be of help in the correct definition of equipment, in numerous practical installation situations.
The dimensioning of an electrical plant requires knowledge of different factors relating to, for example, installation utilities, the electrical conductors and other components; this knowledge leads the design engineer to consult numerous documents and technical catalogues.

This electrical installation handbook, however, aims to supply, in a single document, tables for the quick definition of the main parameters of the components of an electrical plant and for the selection of the protection devices for a wide range of installations.

Some application examples are included to aid comprehension of the selection tables.

Protection and control devices

Good Voltage Regulation and Justified Power Factor Correction

Power factor correction and voltage regulation are closely related. In many cases, the desired voltage regulation is costly to obtain. Larger or paralleled conductors to reduce voltage drop under load are, in many cases, the proper solution.
However, power factor correction may also be justified for four reasons:

1. To improve voltage
2. To lower the cost of electric energy, when the electric utility rates vary with the power factor at the metering point
3. To reduce the energy losses in conductors
4. To utilize the full capacity of transformers, switches, overcurrent devices, buses, and conductors for active power only, thereby lowering the capital investment and annual costs

Location of Current Transformers in HV Substation

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.

An example of calculating the technical losses of T&D lines

Introduction to Losses

There are two types of losses in transmission and distribution line.

1. Technical Losses and
2. Commercial Losses.

It’s necessary to calculate technical and commercial losses. Normally technical losses and commercial losses are calculated separately.

Transmission (technical) losses are directly effected on electrical tariff, but commercial losses are not implemented to all consumers.

Technical losses of the distribution line mostly depend upon electrical load, type and size of conductor, length of line etc.
Let’s try to calculate technical losses of one of following 11 KV distribution line

Vector Group of Transformer

Introduction:

Three phase transformer consists of three sets of primary windings, one for each phase, and three sets of secondary windings wound on the same iron core. Separate single-phase transformers can be used and externally interconnected to yield the same results as a 3-phase unit.
The primary windings are connected in one of several ways. The two most common configurations are the delta, in which the polarity end of one winding is connected to the non-polarity end of the next, and the star, in which all three non-polarities (or polarity) ends are connected together. The secondary windings are connected similarly. This means that a 3-phase transformer can have its primary and secondary windings connected the same (delta-delta or star-star), or differently (delta-star or star-delta).
It’s important to remember that the secondary voltage waveforms are in phase with the primary waveforms when the primary and secondary windings are connected the same way. This condition is called “no phase shift.” But when the primary and secondary windings are connected differently, the secondary voltage waveforms will differ from the corresponding primary voltage waveforms by 30 electrical degrees. This is called a 30 degree phase shift. When two transformers are connected in parallel, their phase shifts must be identical; if not, a short circuit will occur when the transformers are energized.”

 Basic Idea of Winding:

Calculate Voltage Regulation of Distribution Line

Introduction:

• Voltage regulation or Load Reguation is to maintain a fixed voltage under different load.Voltage regulation is limiting factor to decide the size of either conductor or type of insulation.
  
• In circuit current need to be lower than this in order to keep the voltage drop within permissible values. The high voltage circuit should be carried as far as possible so that the secondary circuit have small voltage drop.

Voltage Regulation for 11KV, 22KV, 33KV Overhead Line (As per REC):

• % Voltage Regulation= (1.06xPxLxPF) / (LDFxRCxDF)

Total Losses in Power Distribution and Transmission Lines-Part 2

(2) Non-Technical (Commercial Losses):

• Non-technical losses are at 16.6%, and related to meter reading, defective meter and error in meter reading, billing of customer energy consumption, lack of administration, financial constraints, and estimating unmetered supply of energy as well as energy thefts.

 Main Reasons for Non-Technical Losses:

(1)  Power Theft :

• Theft of power is energy delivered to customers that is not measured by the energy meter for the customer. Customer tempers the meter by mechanical jerks, placement of powerful magnets or disturbing the disc rotation with foreign matters, stopping the meters by remote control.

(2)  Metering Inaccuracies:

• Losses due to metering inaccuracies are defined as the difference between the amount of energy actually delivered through the meters and the amount registered by the meters.
• All energy meters have some level of error which requires that standards be established. Measurement Canada, formerly Industry Canada, is responsible for regulating energy meter accuracy.
• Statutory requirements5 are for meters to be within an accuracy range of +2.5% and – 3.5%. Old technology meters normally started life with negligible errors, but as their mechanisms aged they slowed down resulting
• in under-recording. Modern electronic meters do not under-record with age in this way.
• Consequently, with the introduction of electronic meters, there should have been a progressive reduction in meter errors. Increasing the rate of replacement of mechanical meters should accelerate this process

(3)  Un metered Losses for very small Load:

Total Losses in Power Distribution & Transmission Lines-Part 1

Introduction:

• Power generated in power stations pass through large & complex networks like transformers, overhead lines, cables & other equipments and reaches at the end users. It is fact that the Unit of electric energy generated by Power Station does not match with the units distributed to the consumers. Some percentage of the units is lost in the Distribution network. This difference in the generated & distributed units is known as Transmission and Distribution loss.
• Transmission and Distribution loss are the amounts that are not paid for by users.
• T&D Losses= (Energy Input to feeder(Kwh)-Billed Energy to Consumer(Kwh)) / Energy Input kwh x100
• Distribution Sector considered as the weakest link in the entire power sector. Transmission Losses is approximate 17% while Distribution Losses is approximate 50%.
• There are two types of Transmission and Distribution Losses

1. Technical Losses
2. Non Technical Losses (Commercial Losses)

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