Testing and Commissioning
Testing of power transformer – Measurement of impedance voltage and load loss
The measurement is carried out to determine the load-losses of the transformer and the impedanse voltage at rated frequency and rated current. On Figure 1 above (Circuit for the impedance… Read more
Mar 12, 2014 | By Edvard
Energy and Power
Electrical Thumb Rules You MUST Follow (8)
Accuracy Class of Metering CT Accuracy Class Letter of CT Accuracy Class of Protection CT Continued from part 7: Electrical Thumb Rules You MUST Follow (Part 7) Metering Class CT… Read more
Mar 10, 2014 | By jiguparmar
Electric Motor
Motor Starting via Chokes or Resistors
The series-connected chokes (Figure 1) or resistors (Figure 2) reduce the voltage at the motor and hence also the starting current. The starting torque is reduced by around the square… Read more
Mar 07, 2014 | By Edvard
Energy and Power
The Risk Of Deadly Lightning Current and Few Things You Should Know
Lightning currents are load-independent currents, i.e. a lightning discharge can be considered an almost ideal current source. If a load-independent active electric current flows through conductive components, the amplitude of the current,… Read more
Mar 05, 2014 | By Edvard
Energy and Power
Total Losses in Power Distribution and Transmission Lines (2)
Continued from first part: Total Losses in Power Distribution & Transmission Lines (1) There are two types of transmission and distribution losses: Technical losses (explained in previous part) Non-technical losses… Read more
Mar 03, 2014 | By jiguparmar
Testing and Commissioning
Testing Procedures for HV Voltage Transformers
Equipment required for testing General inspection Insulation Resistance Test Polarity Test Transformer Turns ratio test Following equipment is necessary to perform testings: Polarity test kit Megger 500-5000V Ohmmeter Multimeter Autotransformers… Read more
Feb 28, 2014 | By Edvard
Cables
Practices for grounding and bonding of cable trays
Cable tray may be used as the Equipment Grounding Conductor (EGC) in any installation where qualified persons will service the installed cable tray system. There is no restriction as to… Read more
Feb 26, 2014 | By Edvard
Electric Motor
Physical Structure & Configuration of DC Machines
Figure 1 depicts a two-pole machine in which the stator poles are constructed in such a way as to project closer to the rotor than to the stator structure. This… Read more
Feb 24, 2014 | By Edvard
Electric Motor
Inspection and test procedures for Rotating Machinery, Synchronous Motors and Generators
Visual and Mechanical Inspection Electrical Tests Test Values Visual and Mechanical Tests Electrical Tests Pictures: Electrical machine wired for electrical testing The Electrical Machines Laboratory TABLE 100.10 – Maximum Allowable… Read more
Feb 19, 2014 | By Edvard
Transformers
How challenging can be transporting of a Large Power Transformer (LPT)
Transporting an Large power transformer (LPT) can be quite challenging. LPTs large dimensions and heavy weight pose unique requirements to ensure safe and efficient transportation. Current road, rail, and port… Read more
Feb 14, 2014 | By Edvard
Energy and Power
Effect of utility-induced surges in a steel mill with variable speed drives
A steel mill with variable speed drives (VSDs) had problems of frequent tripping of the VSDs with the indication overvoltage in AC line. Each tripping caused severe production disruption and… Read more
Feb 12, 2014 | By Edvard
Electrical Lectures
What is the short-circuit switching (making / breaking) capacity?
The switching capacity is the r.m.s value of a current at a given power factor cos φ as well as a given rated voltage at which a switchgear or a… Read more
Feb 10, 2014 | By Edvard
Energy and Power
Electrical Preventive Maintenance of Air Circuit Breakers
Remove and clean interphase barriers. Clean all insulating materials with vacuum and/or clean lint free rags. If it is necessary to use cleaning solvents, use only solvents recommended by the… Read more
Feb 07, 2014 | By Edvard
Energy and Power
Purposes and Examples of Safety Interlocking Devices
Most switchboards and motor control centres are fitted with a variety of electrical and mechanical safety interlocking devices. Their purposes are to protect against for example: Withdrawing the switching device while… Read more
Feb 05, 2014 | By Edvard
Energy and Power
Conceptual Model of Smart Grid Framework by IEC
From a communication point of view, each system plays the role of either supplier or consumer of information, or more typically both. In addition to this intersystem communication, these systems… Read more
Feb 03, 2014 | By Edvard
