Energy and Power
Working principle of thermal motor protection relay
Thermal motor protection relays contain three bimetal strips together with a trip mechanism in a housing made of insulating material. The bimetal strips are heated by the motor current, causing them to bend and activating the trip mechanism after a… Read more
Mar 09, 2013 | By Edvard Csanyi
Energy and Power
An Overview Of Short Circuit Current (part 3)
Fault calculations are carried out to find the magnitude of fault current at various voltage levels of electrical system. One of the key components in the calculation process is to determine the total impedance of the circuit from the utility /… Read more
Mar 08, 2013 | By Asif Eqbal
Environment
Why Bats Are Insanely Attracted To Wind Turbines?
Recent studies have reported large numbers of bats being killed at wind farms in many parts of North America and Europe. Project monitoring has also discovered significant bat mortality at the Mexico La Venta II wind farm. Bat kills at wind… Read more
Mar 06, 2013 | By Edvard Csanyi
Testing and Commissioning
Transformer Routine Test – Measurement of Voltage Ratio and Check of Phase Displacement
The no-load voltage ratio between two windings of a transformer is called turn ratio. The aim of measurement is: Confirming the no-load voltage ratio given in the customer order specifications, determining the conditions of both the windings and the connections… Read more
Mar 02, 2013 | By Edvard Csanyi
Electronics
Super Capacitors – Different Than Others (part 2)
Continued from first part: Super Capacitors – Different Then Others (part 1) Equivalent circuit How to measure the capacitance? Charge Method Discharge Method Measure Capacitance Capacitor types Advantages of the supercapacitors Super capacitors can be illustrated similarly to conventional film,… Read more
Mar 01, 2013 | By sravankumarpadala
Energy and Power
An Overview Of Short Circuit Current (part 2)
Continued from previous technical article: An Overview Of Short Circuit Current (part 1) Sub transient reactance Xd” is the apparent reactance of the stator winding at the instant short circuit occurs, and it determines the current flow during the first… Read more
Feb 27, 2013 | By Asif Eqbal
Energy and Power
An Overview Of Short Circuit Current (part 1)
There are essentially four types of faults: three-phase, single line-to-ground, double line-to-ground, and line-to-line. Each of these types of faults can result in different magnitudes of fault current. In all types, however, there is a common element: an abnormally low-impedance… Read more
Feb 25, 2013 | By Asif Eqbal
Electrical Lectures
Super Capacitors – Different Than Others (part 1)
Capacitors store electric charge. Because the charge is stored physically, with no chemical or phase changes taking place, the process is highly reversible and the discharge-charge cycle can be repeated over and over again, virtually without limit. Electrochemical capacitors (ECs) variously… Read more
Feb 23, 2013 | By sravankumarpadala
Energy and Power
And Now Something We All Use – The Socket Outlets
A socket outlet is a female socket connected to the power wiring in the building and will accept the male plug attached at the end of the flexible cord of an appliance such as a vacuum cleaner, electric fire or… Read more
Feb 22, 2013 | By Edvard Csanyi
Medium Voltage
Things You Should Know About Medium Voltage GIS
Environmental Concerns Safety Concerns Special Handling Procedures Installation Concerns Operation and Maintenance Concerns End of Life / Recycling Concerns Conclusion Medium voltage (5-38 kV) gas insulated switchgear (GIS) differs greatly from the medium voltage AIS – Air insulated switchgear commonly… Read more
Feb 20, 2013 | By Edvard Csanyi
Testing and Commissioning
Transformer Routine Test – Measurement Of No-Load Loss And Current
The no-load losses are very much related to the operational performance of a transformer. As long as the transformer is operated, these losses occur. For this reason, no load losses are very important for operational economy. No-load losses are also… Read more
Feb 18, 2013 | By Edvard Csanyi
Electric Motor
Direct Starting Of Squirrel-Cage Induction Motors
The direct starting (Direct On Line, DOL) is the simplest and most cost-efficient method of starting a motor. This is assuming that the power supply can easily deliver the high starting current and that the power transmission components and the working… Read more
Feb 16, 2013 | By Edvard Csanyi
High Voltage
Using High-Speed Grounding Switches
Automatic high-speed grounding switches are applied for protection of power transformers when the cost of supplying other protective equipment is deemed unjustifiable and the amount of system disturbance that the high-speed grounding switch creates is judged acceptable. The switches are… Read more
Feb 15, 2013 | By Edvard Csanyi
Energy and Power
Medium Voltage Switchgear (2) – Selection of Switching Devices
Continued from first part: Medium Voltage Switchgear (1) – Basics of Switching Devices Switching devices are selected both according to their ratings and according to the switching duties to be performed, which also includes the switching rates. Selection according to… Read more
Feb 13, 2013 | By Emmanouil Angeladas
Energy and Power
The Basics of Switching Devices In Medium Voltage Switchgear (Part 1)
According to international rules, there are only two voltage levels: Low voltage: up to and including 1kV AC (or 1,500V DC) and High voltage: above 1kV AC (or 1,500V DC). Most electrical appliances used in household, commercial and industrial applications work with low… Read more
Feb 11, 2013 | By Emmanouil Angeladas
