Electrical Lectures
Fundamental Characteristics of Circuit Breaker
The fundamental characteristics of a circuit breaker are: Its rated voltage Ue Its rated current In Its tripping current level adjustment ranges for overload protection (Ir or Irth) and for short circuit protection (Im) Current-level setting values which refer to the… Read more
Jun 05, 2012 | By Edvard Csanyi
Energy and Power
Understanding Vector Group of Transformer (Part 2)
Vector Groups are the IEC method of categorizing the primary and secondary winding configurations of 3-phase transformers. Windings can be connected as delta, star, or interconnected-star (zigzag). Winding polarity is also important, since reversing the connections across a set of… Read more
Jun 04, 2012 | By Jignesh Parmar
Electrical Lectures
Understanding Vector Group of Transformer (Part 1)
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. The vector group of the transformer is determined by the connection between the windings… Read more
Jun 03, 2012 | By Jignesh Parmar
Industrial Automation
Using MODBUS for Process Control and Automation (2)
To communicate with a slave device, the master sends a message containing: Device Address Function Code Data Error Check Continued from first part of article Using MODBUS for Process Control and Automation (1) The Device Address is a number from… Read more
May 31, 2012 | By Edvard Csanyi
Smart Grid
Electric Vehicles and the Smart Grid
Another source of urgency for the smart grid is meeting goals for getting more “clean” cars and vehicles on the road. Electric vehicles largely eliminate greenhouse gas emissions from vehicle tail pipes. As part of the stimulus package, President Obama… Read more
May 30, 2012 | By Edvard Csanyi
Energy Efficiency
Electric Power Quality and Lighting (part 2)
Continued from first part: Electric Power Quality and Lighting (part 1) Power factor is a measure of how effectively a device converts input current and voltage into useful electric power. Mathematically it is defined as follows: Where P is active… Read more
May 29, 2012 | By Sufi Shah Hamid Jalali
Energy Efficiency
Electric Power Quality and Lighting (part 1)
Concerns about the effects of lighting products on power distribution systems have focused attention on power quality. Poor power quality can waste energy and the capacity of an electrical system; it can harm both the electrical distribution system and devices… Read more
May 26, 2012 | By Sufi Shah Hamid Jalali
Energy and Power
Process Design Basics for Station Facility
The purpose of this article is to establish the design basis electrical system Front End Engineering Design (FEED) and data design or standards uses in the gathering stations facility will be built. Electrical system design refers to the process flow diagram… Read more
May 25, 2012 | By ivan.kurniawan
Power Substation
Transformer Connection Star-Star
The windings of three phase transformers may be connected in by Y or Δ in the same manner as for three single phase transformer. Since the secondary’s may be connected either in Y or Δ regardless of which connection is used on… Read more
May 23, 2012 | By Jignesh Parmar
Industrial Automation
Using MODBUS for Process Control and Automation (1)
MODBUS is the most popular industrial protocol being used today, for good reasons. It is simple, inexpensive, universal and easy to use. Even though MODBUS has been around since the past century nearly 30 years, almost all major industrial instrumentation… Read more
May 21, 2012 | By Edvard Csanyi
Energy and Power
Special considerations when selecting transformer protection
Current transformer ratio selection and performance require special attention when applying transformer protection. Unique factors associated with transformers, including its winding ratios, magnetizing inrush current, and the presence of winding taps or load tap changers, are sources of difficulties in… Read more
May 19, 2012 | By Edvard Csanyi
Cables
Sizing of power cables for circuit breaker controlled feeders (part 3)
Continued from article Sizing of power cables for circuit breaker controlled feeders (part 2) This criterion is applied so that the cross sectional area of the cable is sufficient to keep the voltage drop (due to impedance of cable conductor)… Read more
May 17, 2012 | By Asif Eqbal
Electrical Lectures
Power Measurement In AC Circuits
Power measurement in AC circuits can be quite a bit more complex than with DC circuits for the simple reason that phase shift complicates the matter beyond multiplying voltage by current figures obtained with meters. What is needed is an instrument… Read more
May 15, 2012 | By Edvard Csanyi
Energy and Power
Introduction to instrument transformers
Instrument transformers (ITs) are designed to transform voltage of current from the high values in the transmission and distribution systems to the low values that can be utilized by low voltage metering devices. There are three primary applications for which… Read more
May 14, 2012 | By Edvard Csanyi
Cables
Sizing of power cables for circuit breaker controlled feeders (part 2)
Continued from article Sizing of power cables for circuit breaker controlled feeders (part 1) This criterion is applied so that cross section of the cable can carry the required load current continuously at the designed ambient temperature and laying condition. Ampacity… Read more
May 13, 2012 | By Asif Eqbal
