Electrical Engineering

In many languages both AND and OR operators perform short-circuit evaluation.

there are different types of proximity sensors namely inductive capacitance and infrared. the working principle of inductive proximity sensor is,

it consists coil, oscillator, detector and trigger circuit. when current flows through a coil magnetic field will be generated and when the metal get contact with that field

the voltage is induced in the metal the detector detects this loss in voltage and triggering circuit will give the contact output...

praveen achalkar

MCF mangalore

it is cheaper to use high voltage of transmission because, it is cheaper to boost the voltage

up really high and keeps the current low, also the big pylons with huge insulators will

reduce the energy wasted. the transformer have to step the voltage up for efficient

transmissions and it bring back down to safe usable levels. the voltage is increase

by a step up transformer it's then reduced again at the consumer end using a step

down transformer.

The only thing missing from the above narrative is the reason itself:

Every conductor has some resistance. When an electric current flows through a

conductor, the resistance of the conductor causes loss of some of the energy. The

loss is LESS when the voltage is higher and the current is smaller. The big pylons,

the huge insulators, and all the step-up and step-down transformers wouldn't be

necessary if the voltage was the same 110 volts all the way from the generating

plant to your house. But shipping it at high voltage saves more energy than the

cost of all that extra infrastructure.

The secondary of a CT must always have a load connected. An open circuit secondary can result in the development of a dangerously high secondary voltage. If a CT is energized but is not used, the output terminals of the CT must be shorted out.

Yes, like the dynamo on a bicycle that provides power for the light, instead it can run an electric motor with the help of a few cheap diodes(Bridge diode setup)

Very few conductors obey Ohm's Law, and its the rise in temperature of the conductor when current flows though it that prevents it from obeying Ohm's Law. Some alloys, such as constantan, obey Ohm's Law over a limited range because, over that range, changes in temperature don't affect their resistance.

It's really time that we stopped teaching Ohm's Law, as it is not universal, and applies to very few conductors and hardly any electronic components!

The 2011 National Electrical Code introduced a new Article. 110.24 - requiring a LABEL on non-dwelling Electrical Services indicating both the date and the Maximum Available Fault Current (MAFC) calculation at the Line In Terminals of the Main Overcurrent Protective Device. The Formula is relatively simple once the Electrical Contractor obtains the FAULT DUTY (Also termed Maximum Fault Current) from the Utility. This data represents the Transformer KVA Rating, the voltage at the secondary and the Per Unit Impedance at the Secondary terminals of the providing Transformer. MAFC is then calculated considering the Type of Wire from the Transformer terminals, the type of raceway utilized, and the Number of Sets of Service Entry Conductors associated with the installation.

The formula for a typical 3 phase 4 wire Service is:

Sq Root of 3 X L (Wire Length) X I (Short Circuit Current Utility provided) DIVIDED BY:

C (Constant) X n (Sets of SE Conductors X E (Line to Line Voltage XF Secondary)

This answer is termed Calculating the "F" Factor. F factor is then simply compared to a Chart to find a multiplier "M". {Always Less Than One (1)}

This multiplier M is times the XF SCC. This answer is the Maximum Available Fault Current. Note that the type of raceway, PVC or Metallic, the type of Wire, Copper or Aluminum, the number of "barrels" will affect by inductive reactance or impedance of the conductors, by lowering, to a small degree, the SCC at the

providing transformer. The most difficult number in the formula is the Constant "C", which must be obtained from an outside source such as Cooper Bussman's Point to point AFC calculation chart. Both "C" and "F" > "M" are located in the

Point to point Guide at Cooper Bussman. Electrical Inspectors will verify the MAFC Calculation and the Date of the Calculation when the Electrical Contractor places the required label on the Service Equipment, per NEC 2011 110.24

Keep in mind the Service Equipment (SUSE Rated) must have a SCCR Rating on its manufacturers plate. The SCCR (Short Circuit Current Rating) Must be higher than the Maximum Available Fault Current at it's Service Line in Terminals.

August 22, 2011 B. Head Certified Electrical Inspector, All Structures.

what is current capacity of 95 sqmm cable?

We know that relative speed is responsible to induce voltage. If rotor and the rotating field (stator) speed is same, no voltage will induced because relative speed will be zero. For IM relative speed is not zero and it does not move with sync. speed, and so it is called asynchronous motor.

MCC (Motor Control Center) panel is used for distributing power to electric motors. mcc is made up of steel structure to contain the combination motor control units,wire ways,internal wiring and busbars.

Air conditioner system senses the room temperature and then decides how much cooling has to be provided to room as per the setting. Say u need only 20 degree Celsius only.

To elaborate, in a closed loop system, the output in some way shape or form is fed back into the input of the control system. With an air conditioning system, the output is temperature. This temperature is read, and fed back into the control system to determine if additional cooling is needed or not.

An example of an open loop system would be if you programmed the air conditioning to turn on from 11AM to 5PM, then turn off. The output of the system (temperature) doesn't effect the input (when the system runs).

God of the motors. just ask milwaukee

In dc motors, the electric power is conducted directly to the armature (i.e., rotating part) through brushes & commutator. Hence, in this sense a dc motor can be called as a Conduction motor.

However, in ac motors, the rotor does not receive any electric power by conduction but by induction in exactly the same way as the secondary of a two winding transformer receives its power from the primary. That is why such motors are called as Induction motors. An induction motor can be treated as a rotating transformer i.e., one in which primary winding is stationary but secondary is free to rotate.

A DC shunt motor is a motor using DC supply with the the inductor connected parallel to the armature.

Plastic is a good insulator and a bad conductor of electricity, which makes it a good material to protect people from electric shocks when handling appliances.

On top of that, plastics are inexpensive and easy to shape.

Purpose: The megger tests the integrity of the insulation between conductors that run side by side and do not physically meet or connect. Meggers or Mega-ohm testers also are typically used to test the dielectric in coaxial cable. Meggers are used to test the insulation of buried cables by placing a lead to earth ground and one lead to the outer conductor of a coax cable or any or all conductors of multiple (more than one) buried wires. Method: introduce a high enough voltage to the conductors eventually the current will travel betwen the conductors. Read the indicator to see the amount of resistence to current flow on the meter indicator. the reading will generally be in millions of Ohms (megohms)

A 2.2 k resistor would be banded red, red, red, and possibly other bands depending on tolerance, etc.

The first two bands, red and red, mean 2 and 2. The third band means 2 zeros. The result is 2200.

0 black

1 brown

2 red

3 orange

4 yellow

5 green

6 blue

7 violet

8 grey

9 white

Fourth band:

none 20%

silver 10%

gold 5%

If the third band is gold or silver, then the multiplier is 0.1 or 0.01, respectively. For example, red, red, silver means 0.22 ohms.

P1 = V I1, Therefore, if P2=0.5*P1, then

I2=0.5*P1/V, or 0.5*I1

and if P3=2*P1, then

I3=2*P1/V, or 2*I1

In other words, current is proportional to power and inversely proportional to voltage.

-48 v is given to BTS because in this voltage Noise

generation is minimum.

Because two terminal comes out from the battery and

through red color wire we ground the +ive terminal so that

possibility of noise interference will get zero because noise

occurs only in the +ive terminal that's why we use -ive

voltage in the BTS.

1 megohm is 0.1 gigaohm.

1 gigaohm is 1000 megaohm.

1 megohm = 1,000,000 ohms = 106 ohms.

1 gigaohm = 1,000,000,000 ohms =109 ohms.

The secondary winding's current rating is the rated apparent power of the transformer (expressed in volt amperes) divided by its voltage rating (expressed in volts). This applies to both step down, and step up, transformers.