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This riddle is subjected to precommisioning test of an instrumentation system in hypothetical industrial plant.
Author : Hamid - From: IRAN
The teacher was reviewing VOLTA experiments and how battery invention. One of the students asked him:
Author : Hamid
After one sever earthquake happened in the hypothetical nuclear power plant area, following observations were reported by special investigation committee that were authorized to estimate earthquake demolition in power plant.
Author : Hamid
Let's imagine the year 2107.In that time electrical power will be generated in nuclear power plants and electrical energy will be produced in big nuclear reactors.Also the electrical energy will be transmitted by superconductor cables.
Author : Hamid
Control and protection electrical circuits are one of the important portions of electrical systems designed and shown by standard symbols.
Author : Hamid
Consider two non parallel wires each carrying a current which located at one plane surface.
Author : Hamid - From: Iran
There are two sensitive auxiliary relay in one portion of DC control circuit (relay no.1 & no.2) separated by one semiconductor diode. Two relays (R1, R2), their two run up contacts (C1, C2) and that mentioned diode bridge (D) is located in "H" form.
Author : Hamid
Two lamps each of 60W & 100W with similar rated voltage are connected in series to a single phase & neutral ,240 V electric supply as per diagram.

Author : Ratnagiri Ramkumar from INDIA
According to some technical recommendation, we must  concern about metal under ground structures (e.g. pipe lines) corrosion in neighbor of power transmission lines.
Author : Hamid - From: IRAN
dc polarity in telecom
Why we use positive conductor as a grounding and negative for switching in telecom equipment?  
Author : maamir from pakistan
What is checking method of diode kit installed in genset and purpose ot this kit for excitation system?
Author : maamir from pakistan
what are the method of checking of instrumentation installed e.g Hour meter Voltmeter etc and safities?
Author : maamir from pakistan
A three phase and three wire energy meter has installed in a medium voltage network with a lot of third harmonic current and unbalanced load (approximately %10).
Author : Hamid - From: IRAN

I need more explanation or there is any document regarding the " Cross Current Componding"
Author : ashan - From: Iran
While welding  pipeline joint,using Arc welder machine(transformer),a welder was electrocuted,in spite of taking all safety measures and using Personal protective equipment.
Author : n.v.Mani - From: INDIA
30 KVA DG Set not take up the load of 7.5 H.P motor through AVR. While it runs on mains.Why?
Author : Harsh - Sisodia - From: India
Hi, I am upgrading power transformer from 220 KVA to 400 KVA due to increase in load. I have 185mm running from Power transformer to 400 V, 3 Phase distribution system.
Author : - - From: Pakistan
Why the shape of ball type items are fixed on earth screen cables top of power transmission lines? Please Explain?
Author : Ravi Perera
I have been asked this question below by one of my customers and I was wondering if any one can offer any advice.
Author : GUEST
Can some one help with calculation methodology to workout the rating of the Battery for UPS.
Author : GUEST
We have two similar capacitors, one of them is charged amount Q coulomb and V volt, other is empty about any charges.
Author : Hamid - From: IRAN
Please let me know for the same load cycle of both Lead Acid Plante Type Batteries and Ni-Cad Battery, what will be the capacity in  AH of NICad Battery  in relation (in percentage) to AH capacity of Plante Battery.
Author : V.Ambarani
Why dc component is present in short circuit current and how they are  appering during short circuit condition?
Author : kailash kumar - From: INDIA
A big industrial Company consist a shop with a little luminance space, their company workman called it dark workshop. That building is equipped by a lot of filament lighting devices (app. 80 numbers lamp) but it hasn't enough luminance for normal activities.
Author : Hamid - From: IRAN
one mcc panel contains feeders for 4 nos 5 hp motor,2 nos 10hp motor,3 nos 3hp motor,3 nos 1.5 hp motor.what will be the amps rating of incoming feeder?
Author : GUEST

I am looking into silicon solar cells but cannot find any sources which explain why open circuit voltage decreases with rise in temperature.
I know that voltage decreases with temperature but why?
Author : GUEST
What min. distance between different phases shall be considered in switchgears?
Author : GUEST
I am doing my Phd on Distribution Generation and i have studied the relevant standards. As far as concerning the permittable penetration level there is nothing to be found.
There is not a penetration level limit, neither an official definition of it. It is the ratio of what?
Author : GUEST
How can we estimate the inductance of rectangular strip bus bars in three phase system?
Author : GUEST
What is the influence of capacitor banks existing in short circuit level of power systems?
Author : Hamid - From: IRAN
Is there any limitation for using of capacitor in electrical systems as power factor corrector?
Author : ALI - From: IRAN
Super conductor cables are supposed to be the cables having zero resistance/impedance, so that it carries infinite current capacity which will further lead to v=0 since v=ir and r is 0 therefore v=0 how  could current flow when potential difference is  zero
Author : bipul - From: INDIA
In a switchboard some where I have seen 3P main breaker and some where 4P breaker, what is the technicality about breaking of neutral as well. please explain technical point of view.
Author : manirul - From: India

Is there any limitation for hazardous through current from human body?
Author : akbari nejad - From: IRAN
As you know the meaning of recorded KWH by electrical energy meters is the actual amount of produced energy by power source or the actual amount of consumed energy by loads in power system.
Author : Hamid - From: IRAN
When we use individual loads we use demand factor when we apply to a group of load we use diversity factor ....
Author : Iqbal Khan - From: Pakistan
Why strong spring usually is used in high current circuit breakers? Why required forces for operation of circuit breaker shall be increased when its rated current or short circuit capacity is increased?
Author : Mohammed - From: Syria
When bright of our illumination lamp reduce, we note the problem in quality of transmission electrical energy.
Author : Hamid - From: IRAN
What is local power factor compensation and its benefits?
Author : Tira - From: Syria
In design of a power plant for electricity generation , what is the relationship between design ambient temperature , daily temperature and average yearly temperaure . Is there any , standard , guide or reference in this connection ?
Author : AMIR KHASHAYAR - From: Iran
Could some one ps help me in determining 'Mechanical Heating  vs Equivalent input power'.
Author : SAM ELIEZER INJA - From: India
What are the types of Power Distribution Cable Termination and Joints?
Author : baba - From: Qatar
What is difference between voltage fluctuation and flicker and how can reduce voltage fluctuations?
Author : NASER - From: Egypt
If I need to connect two ac sources in parallel, what are the things I have to consider?
Author : Kotteeswaran - From: Chennai, Tamil Nadu
Can anyone send me a soft copy of the a checklist for handling over the new installation/comm'g of 11KV substation/OHL to maintenance DEPT
Author : BABA - From: Qatar
How many Secondary Substations (11kv/415v) are allowed in a Ring or Radial Cirucit in 11 kv Distribution System?
Author : BABA - From: Qatar
what is the relation ship between ac and dc resistances of a wire or coil?
Author : Sinnadurai Sripadmanaban - From: Srilankan
mounting height of power receptacles in homes and offices-how it affects users
Author : Unknown
why the supply frequency is 50hz and not 25hz or 100hz?
Author : mahesh - From: India
If we connect an incandescent or CFL or vapour lamp(FL/Hg/Na/MH) via a diode will there be flicker and will the power consumption be halved?
Author : Sinnadurai Sripadmanaban - From: Srilanka
Which is the best kind of lamp recommended for illuminating security fence and adjoining areas?.
Author : Sinnadurai Sripadmanaban - From: Srilanka
Can you give average values of power factor of appliances like incandescent,CFL , mercury vapour and other types of lamps and appliances like radio,TV,mixer/grinder, microwave oven,ceiling fan,fax,photocopier,computer,desk calculator,hair drier etc?.
Author : Sinnadurai Sripadmanaban - From: Srilanka
Can we collect charges in clouds before it discharges to objects in ground? Also is it possible to store energy discharged via a down conductor during a lightning strike in a capacitor?
Author : Sinnadurai Sripadmanaban - From: Srilanka
It is stated in IEC that 50&60Hz are most dangerous frequency regarding electrical safety. Then why these frequencies are selected universly for electric supply
Author : V.K.Nambiathiri - From: India
How to add extra kw in respect to diversity factor
If contract demand is 4500 KVA and in the month we received maximum demand is 3708 KVA.If we want to add 150 kw extra ,then how we can add it in respect to diversity factor?
Author : Naveen singh - From: India
Selection of demand factor for various loads
Author : soman - From: India
I was replacing the switch (1-way) controlling the fluorescent lighting in my garage.  The lamps were initially off from the switch but when I switched the circuit off at the MCB to isolate the circuit, ....
Author : Mike - From: UK
Non- Linear loads is more than 50 % of total connected load . Explain the selection of capacitors and also explain the advantages of High and Ultra High duty  capacitors.
Author : soman - From: India
Two  generator  sets are operating in parallel.  frequency and voltage  of gen sets is keep slightly more than system frequency . WHY? And also calculation of gen set frequency?
Author : soman - From: India
Currently we are installing 11kv, 300mm square cable from our substation to main source and the distance is 16km. ...
Author : Alex - From: Phil.
Why phase or positive is controlled in an electrical circuit. why not negative or neutral???....
Author : Kanagarajan - From: India
When the capaciotr bank is connected to a system with light load ,why we observe increase in voltage?
Author : Ashutosh Pailwan
why flame is coming when the phase cable connected to neutral cable?
Author : bojanki sankararao
To solve a KVAR sharing issue between CAT and Cummins
On my power station, there are 17 Cummins Gensets of 1000 KVA with PCC3100 Panel.
Author : Romain Daniel - From: France
Using a common stabilizer in the incoming of Electrical supply to a house results Energy savings?
Author : A. Selvakumar - From: India
how to adjust the mis matching CT in a low impedance transformer differential relay circuit
Author : Palaniraj - From: Indian
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