Electrical Engineering

In short circuit test very low voltage at primary approx 5 % of the rated voltage is given and secondary is short circuited by an ammeter. Due to low voltage very low flux is developed in core of the transformer and due to that iron losses are very low which can be neglected. By Rizwan: actually it is operated at (10-15)% of the rated voltage and as you know n case of low voltage low magnetic flux is produced and then there will...

On three phase 208 volts one leg does not have the potential of 208 volts. It takes two legs to provide the 208 volts. The potential is across AB, BC and CA. Voltage to the grounded neutral A-N, B-N and C-N will produce a potential of 120 volts. In a wye configured secondary three phase four wire you have the potential of 120/208 volts. ...

yes lenz law states that every current opposes the reason which cause the generation of that current . it is very useful for considering back emf in dc motor. The lenz law also help us to determine the supply voltage of DC motor. ...

Ohm's Law states: "The current flowing through a conductor is directly proportional to the applied voltage, provided the temperature of the conductor remains constant." It specifically refers to conductors and not resistors. And it takes into consideration the need to maintain a given temperature as the voltage and current vary. At the time, Georg Ohm already knew that allowing the temperature to vary would break the constant ratio. Keep in mind that this was a historic new understanding that he had discovered was applicable...

The Current-Voltage relationship of a diode is not constant (not a straight line) and hence the resistance cannot be measured. Due to this non-linear nature of the the curve, there exists a unique value of resistance at every point of the curve which is called dynamic resistance (not static of constant resistance). The dynamic resistance equals the change in voltage divided by the change in current, when the voltage is changed by a small amount. In other words it is the slope...

Inductive load power is reactive, it is given by the formula: pL(t)=VL(t)IL(t), in time domain (instant power); PL(s)=VL,RMS(s)IL,RMS(s), in Laplace transform domain (RMS denotes root mean square amplitude). VL is the voltage across the inductor L and IL is its current (current enters in the "+" voltage reference pin, by applying user convention in which absorbed power is positive). Power is reactive since voltage and current are always in quadrature: VL(s) = s L IL(s), in Laplace domain (derived from the time-domain formula vL(t)= L diL(t)/dt). A real-life inductor will...

The instrument used to measure electrical current is called an ammeter, which is actually a shortened form of 'amp meter'. The current is measured in amperes. In scientific labs, a much more sensitive instrument called a galvanometer is used to measure very small currents. ...

A: Hissing is because is overheating before it destroy itself. But other noises are caused by loose lamination of the core. B: Hissing noise is produced due to this reason but here is another important point is about frequency (e.g for 50 Hz) the core lamination face attractive and repulsive forces fifty times in one cycle because frequency is 50 Hz. Another Answer The original answer is unnecessarily melodramatic. Transformers are fitted with protective devices that will disconnect the transformer long before a rise in...

Generally a single-phase transformer will have two windings. One of the Low voltage side and one on the high voltage side. North-American distribution transformers will have three: one high-voltage winding, and two low-voltage windings connected in series. However... ...a single-phase transformer can also have several primary and several secondary windings. The primary windings can be connected in series or in parallel with each other, as can the secondary windings. For example, taking the primary winding as an example, it could consist of two 120-V rated...

There are various types of bus bar arrangements 1. single bus bar arrangement 2. double bus bar arrangement 3 Tie bus bar arrangement ...

A welding transformer is an electrical transformer used in welding power supply. It pulls relatively low current drawn from the mains power (typically limited to 15 A to avoid tripping the circuit breaker) and converts it to the typical 50 A to 500 A used in arc welding and higher currents used in spot welding. The main difference between a Normal Step Down Transformer & a Welding transformer , is Not only to Step Down ( lower ) the outlet supply voltage...

The spacial distance between line legs increases as the line voltage increases. This also holds true from line voltage to ground. So as no voltage was stated then no correct answer can be given. ...

A motor converts electrical energy into mechanical energy and a generator converts mechanical energy into electrical energy. Longer answer The primary difference between a motor and a generator is that one converts electrical energy into mechanical energy (that's the motor) and the other converts mechanical energy into electrical energy (that's the generator). In some cases of direct current (DC) machines, but not alternating current (AC) machines, there is so little difference that a single device (it might be called a motor-generator) can be used as...

There is no voltage in three phase wire. The ability of wire to carry voltage is dependant upon the insulation that surrounds the wire. The thicker the insulation the higher the voltage potential can become. Three standard insulation voltages are 300, 600 and 1000 volts. Another Answer First of all, there is no such thing as a voltage 'on' a wire. 'Voltage' is another word for 'potential difference', so a voltage can only exist between two wires. Voltages in three-phase systems are generally specified...

It depends on the voltage, the sag of the line, and the distance between towers. Generally there is a minimum height that the power line must be above the ground, defined by voltage level. If the geography requires there to be a great distance between structures (such as a river crossing), the towers will be made tall enough to accomodate this. In general, the lower voltage lines may be as short as 25 feet, while taller ones can be over 200 feet. ...

In circuit analysis, there is steady state and transient conditions. transient conditions are how the circuit acts immediately following some action (such as turning on power, closing a switch, losing power, etc.). Steady state conditions is everything else. ...

There are several type of circuit breakers now a day we are using these are as follows: 1. M.C.B. (Miniature circuit Breaker) Rating : 1, 2, 4, 6, 10, 16, 20, 25, 32, 63 Amperes 2. M.C.C.B. (Miniature current circuit Breaker) Rating : 10, 16, 20, 25, 32, 63, 100, 200, 250, 400 Amperes. 3. A.C.B. (Air Circuit Breaker) Rating : 400, 800, 1000, 1200, 1500, 1800, 2000 Amperes. 4. A. B. Switch (Air Breaker) used in High tension line. 5. SF6 Breaker (Contact break...

The plural of 'ohm' is ohms, not ohm's. The alpha-numeric code for identifying the resistance of a resistor is quite straightforward. The letter is used as a multiplier. For example, k = x1000 and M = x1000 000. In other words, k represents kilo, and M represents mega. The position of the letter represents the position of the decimal marker. So, 1M5 represents 1.5 x 1000 000, or 1.5 megohms. 15M represents 15 x 1000 000, or 15 megohms. etc. Similarly, 1k5 represents 1.5 x 1000, or 1.5...

Answer for USA, Canada and countries running a 60 Hz power supply service. If it is a 220 volt motor with split windings to run on 110 volts then there is usually a connection chart on the motor somewhere on or behind the motor wiring cover plate. There will be at least 4 lugs for running it in series for 220V or parallel for 110V and possibly a couple more terminals to reverse its direction. Enter the model number of the motor on...

You cannot. It must be taken out of the circuit and then tested on its own. That's not 100% true because, if it has wires at its ends, you can cut through one wire with an appropriate tool and then test the capacitor "out of circuit". If the capacitor is ok you can then re-join the two cut wire ends by applying a blob of solder carefully. (But, to avoid damaging the capacitor, use a suitable heat sink to shield the body...

It depends. If it's an inductive ammeter (the kind that clamps around a wire), it won't work at all. If it is the type of ammeter that is actually placed in the circuit, it will work but it won't be accurate. Comment Actually, modern 'clamp on' ammeters WILL measure d.c. currents. It uses the Hall Effect to measure the current. ...

Auto Mains Failure

A search on the Internet is probably your best bet.

Use either DC to Dc converter or voltage regulators for the required voltages. Answer A common method is to use a voltage divider circuit. This comprises a number of resistors, connected in series, across the power supply. This creates a series of voltage drops across each resistor and, by choosing resistors of appropriate value, the desired load voltage can be achieved. For example, if three identical resistors are connected in series across 9 V, then the voltage across each resistor will be 3 V, and...

For normal power factors (pf=80%), you have 0.8 kW for every kva. In general however, kW = pf x kVA. Where pf is the power factor, it is the cosine of the angular difference between the voltage and the current of a circuit in alternating current circuits. ...