Transformers
What is transformer rating based on?
In the U.S., transformers are rated based on the power output they are capable of delivering continuously at a specified rated voltage and frequency under “usual” operating conditions without exceeding prescribed internal temperature limitations. Insulation is known to deteriorate with… Read more
Jan 30, 2013 | By Edvard Csanyi
Energy and Power
How to manipulate energized conductors with hot stick
Hot sticks are poles made of an insulating material. They have tools and/or fittings on the ends which allow workers to manipulate energized conductors and equipment from a safe distance. Hot sticks vary in length depending on the voltage level… Read more
Jan 28, 2013 | By Edvard Csanyi
High Voltage
High Voltage Substations Overview (part 2)
Continued from first part: High Voltage Substations Overview (part 1) Transformers are used for the transformation of high and medium voltage to low voltage, flanked by specific protective devices and control systems, which constitute the low voltage distribution substations. A… Read more
Jan 26, 2013 | By Emmanouil Angeladas
High Voltage
High voltage substations overview (part 1)
High voltage substations are interconnection points within the power transmission and distribution systems between regions and countries. Different applications of substations lead to HV substations with and without power transformers: Step up from a generator voltage level to a high voltage… Read more
Jan 25, 2013 | By Emmanouil Angeladas
Energy and Power
Comparison of Protection Relay Types
This comparison summarize characteristics of all protection relay types described in previously published technical articles: Using Protective Relay For Fighting Against Faults The Good Old Electromechanical Protective Relay The Solid State Relay (Static Relay) Overview Few Words About Digital Protection… Read more
Jan 23, 2013 | By Jignesh Parmar
Cables
Differences Between Earthed and Unearthed Cables
In HT electrical distribution, the system can be earthed or unearthed. The selection of unearthed or earthed cable depends on distribution system. If such system is earthed, then we have to use cable which is manufactured for earthed system. (which… Read more
Jan 21, 2013 | By Jignesh Parmar
Energy and Power
Power measurement in a three-phase system
Electrical power is measured with a wattmeter. A wattmeter consists of a current coil connected in series with load, while the other potential coil is connected parallel with load. Depending on the strength of each magnetic field movement, the pointer… Read more
Jan 19, 2013 | By Edvard Csanyi
Cables
Underground residential distribution layouts
Where general appearance, economics, congestion, or maintenance conditions make overhead construction inadvisable, underground construction is specified. While overhead lines have been ordinarily considered to be less expensive and easier to maintain, developments in underground cables and construction practices have narrowed… Read more
Jan 18, 2013 | By Edvard Csanyi
Transformers
D.M.C.R. Protection Relay for Oil Transformer
Introduction to D.M.C.R. Faults detected on live transformer unit: Dielectric fluid level is detected as low Overheating is detected Excess pressure is detected Standards Possibilities of D.M.C.R.: Oil level control and gas detection Pressure control Temperature control The DMCR is… Read more
Jan 16, 2013 | By Edvard Csanyi
High Voltage
Purpose of Disconnect Switches In HV Substation
Switches may be of several types, the common characteristic is that none are designed to interrupt fault currents and the insulation or insulators associated with them must coordinate with the rest of the system and a BIL (Basic insulation level)… Read more
Jan 14, 2013 | By Edvard Csanyi
Cables
Testing and Commissioning of MV/HV Cables
Compare cable data with drawings and specifications. Inspect exposed sections of cables for physical damage. Inspect bolted electrical connections for high resistance using one or more of the following methods: Use of a low-resistance ohmmeter in accordance with Section 1.2 above…. Read more
Jan 12, 2013 | By Edvard Csanyi
Energy and Power
Discrimination between residual current circuit breakers (RCCBs)
The operating principle of the residual current release is basically the detection of an earth fault current, by means of a toroid transformer which embraces all the live conductors, included the neutral if distributed. In absence of an earth fault,… Read more
Jan 11, 2013 | By Edvard Csanyi
Testing and Commissioning
Testing and Commissioning of Substation DC System
Power substation DC system consists of battery charger and battery. This is to verify the condition of battery and battery charger and commissioning of them. Following instruments will be used for testing: Multimeter. (Learn how to use it) Battery loading… Read more
Jan 09, 2013 | By Edvard Csanyi
High Voltage
Environmental Stresses On External Insulation
The external insulation (transmission line or substation) is exposed to electrical, mechanical, and environmental stresses. The applied voltage of an operating power system produces electrical stresses. The weather and the surroundings (industry, rural dust, oceans, etc.) produce additional environmental stresses…. Read more
Jan 07, 2013 | By Edvard Csanyi
Testing and Commissioning
Transformer routine test – The measurement of winding resistance
Measurement is made to check transformer windings and terminal connections and also both to use as reference for future measurements and to calculate the load loss values at reference (e.g. 75ºC) temperature. Measuring the winding resistance is done by using… Read more
Jan 05, 2013 | By Edvard Csanyi
