0
Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
The abbreviation, 'PT', stands for 'potential transformer' (in Britain, the abbreviation is 'VT', and stands for 'voltage transformer'). This, together with a 'current transformer', falls into a category of transformer known as 'instrument transformers'.
A 'PT' or 'VT' is used to reduce a high voltage to a level of voltage that can be safely read, remotely, by regular a.c. voltmeters or to provide inputs to high-voltage protection relays, while electrically- isolating the secondary circuit from the high-voltage primary circuit for the purpose of safety.
Why doesn't my electromagnet work when i only wrapped the wire around the nail for ten times?
If there are only a few wraps, the magnetic field will be weaker than if there are many more wraps.
What is the required color identification for the core of a protective conductor?
In Europe, the standard color for the protective (earth) conductor is a green/yellow stripe, although in most residential two-core (line and neutral; the protective conductor isn't counted) wiring, the protective conductor is bare.
Advantages of a full wave rectifier?
In half wave rectifier there are only two diodes connecting opposite to each other , hence their is possibility 0f only 90 degree phase will gane to us .thus we got the dc voltage wave . The half wave rectifier is cheaper one,it will give the pure dc.
Why in summers voltage coming is less in houses?
This is commonly a problem called "voltage drop". Simply, if you have any power supplying unit connected to an electrical load, it draws an amount of electrical current based on the load value. The voltage at the supply terminals is higher than on the load terminals, this is due to the resistance (impedance) of the connection wires (cables). The more the connection resistance (more resistance means less cross-sectional area), the less the load voltage (if source voltage and load current are kept constants). Another thing that affects the load voltage, is the load current itself. If the load current increases, the load voltage decreases (if source voltage and connection resistance are kept constants).
This means that any load current or connection resistance increase mean that the load voltage will decrease. This is exactly what happens in summer. In summer the ambient air temperature is high and hence all connection network elements (wires, cables, TL...) have higher resistance. Plus, most of the air conditioning units operate in summer (higher load current) which represent a bulk load to the network.
What sezi cable can you use to connect 10amps motor 3 phase?
14/3 copper with ground on a 25 amp breaker
Before I get chastised for recommending that 14 gauge wire be protected with a 25 amp breaker, which would be in violation of standard wiring requirements, Sec. 240.4(G) of the NEC tells us that the standard wiring requirements, i.e. 15 amps on 14 gauge wire, does not apply to motors. Table 430.52 tells us that an inverse-time circuit breaker (that's a standard type breaker) can be set to 250% of the FLC of the motor and 430.22 tells us that the branch circuit conductors are sized at 125% of FLC.
The question does not say that 10 amps is the FLC. The nameplate rating of a motor is not the FLC. FLC is determined by using the tables in Sect. 430. The name plate rating is used only for sizing current overloads, called "heaters". For my answer I have assumed 10 amps is the FLC.
What does the letter 'H' mean in electrical circuits?
It means generally "Hi"side of some electrical device (such as Hi -H- or Low -L- transformer side)
What is the value of resistivity?
Electrical resistance is measure in Ohms. A function of voltage divided by current. It is also dependant on the length and cross sectional area of the conductor.
How can Swinburne's test be adopted for series motor?
the method can not be used in the case of a d.c series motor
How do you calculate how to split a 7.5Kw load over 3 phases?
A 7.5 kW three phase load will be balanced by the manufacturer. When connected to a three phase source the line current on each phase will be equal.
= A Reactance Modulator =
A reactance modulator changes the frequency of the tank circuit of the oscillator by changing its reactance. This is accomplished by a combination of a resistor, a condenser, and a vacuum tube (the modulator) connected across the tank circuit of the oscillator as in Fig. 33 A, and so adjusted as to act as a variable inductance or capacitance. Fig. 33 A. Principle of a reactance modulator The net result is to change the resonant frequency of the LC circuit by amounts proportional to the instantaneous a.f. voltages applied to the grid of the modulator tube, without changing the resistance of the LC circuit or the amplitude of the oscillations. A modulator circuit is shown in Fig. 33 B. Fig 33 B. A reactance modulator The voltages supplied to both the modulator and oscillator must be carefully stabilized to prevent undesired frequency changes. The speech amplifier (Fig. 33 A) does not have to deliver any power and need supply only a small output voltage, say 10 or 15 volts. A pentode and triode, R-C coupled, will be sufficient even with a sensitive microphone and a high-powered oscillator. The frequency change of LC per volt change on the a.f. grid of the modulator tube will be greater when C1,Fig. 33 B, is made smaller. The blocking condenser C2 has a comparatively high value, and hence offers but small reactance to r.f. currents. Fig. 19 H. An RC phase shifter In Fig. 33 B, the radio-frequency voltages which are developed across the tank in the oscillator circuit also appear across the RC1 circuit and across the parallel 6L7 modulator tube. Now look up the phase-shifting circuit of Fig. 19 H. The resistance r has been replaced by the internal resistance of the modulator tube of Fig. 33 B. The voltage drop across C1 is 90° out of phase with the tank voltage. It is applied to the control grid of the 6L7 whose r.f. plate current responds in the same phase. Thus this current is made to lag 90° behind the tank voltage. The r.f. plate current flows through the tank circuit and, combined with the current therein, is equivalent to a new current whose phase differs from the normal value just as though an additional reactance (not resistance) had been connected in with L and C. This, of course, changes the frequency of the LC circuit and hence of the transmitter. When a.f. is fed into the modulator tube, it causes proportionate changes in the r.f. plate current and hence in the equivalent reactance of the LC circuit.
What is the purpose of OC and SC tests on single phase transformer?
Open circuit and short circuit tests are performed to determine transformer characteristics. In the case of a single phase transformer, SC tests would be performed to determine the impedance. The open circuit test will give excitation information (% excitation at specific voltages, often 90%, 100% and 110%, and no load losses).
What is the meaning of ingress in electrical?
You are probably referring to moisture ingress. Moisture ingress into underground electrical cables, particularly high-voltage cables, can act to break down the insulating properties of that cable, and lead to a short circuit. Accordingly, underground cables incorporate a sheath (lead in older cables), which is impervious to moisture ingress, which surrounds the cable cores, and is located beneath the outer armouring. But moisture ingress can occur with all types of electrical equipment, and the manufacturers take steps to prevent this from happening.
How do they make the magnets so strong for the Maglev train?
Lots of electricity ... which takes power.
In a power station where dc is actually converted to ac while distribution?
The generated voltage in a power station is AC voltage, not DC. So, it is never converted to AC, because it is already AC.
What happens when you lose an input phase on a three phase bridge rectifier?
If the rectifier is wye connected, ripple will increase. If it is delta connected, ripple will substantially increase. Whether or not the rest of the rectifier, filter, and regulator are damaged will depend on how much current is being pulled by whats left, and by how deep the ripple actually becomes.
A megger measures very high resistance to check insulation, therefore it must use very high voltages so as to detect the very small current flowing.
Question is incorrect. in a 240 Volt single phase circuit, how can you have A phase and B phase?
A fractional horsepower motor is an electric motor with output power 746 watt or less watt.
Adept motors is the best manufacturer and supplier of FHP motors in pune,maharashtra and India. It offers thousands of choices the FHP motors including reversible motors with high quality. Adept motors provide wide range and best quality of FHP motors with best quality and features.
For more detail information 9766963047.
Where is the circuit breaker on a 1995 Jaguar XJR?
The Circuit Breaker on a 1995 Jaguar XJR is located under the firewall in place of the blue hydro chronic area that is in between the legs of the upsidedown woman that fell on to her knees when the location of the firewall was found to make contact with the engine at 3.2 seconds then became the location of the circuit breaker of the 1995 Jaguar XJR. Your Welcome.
Why does a synchronous generator typically run at lagging power factor?
When a synchronous generator is running at lagging power factor the current it supplies lags its terminal voltage. Thus it acts as a source of reactive power, or magnetizing vars.
Reactive power is needed to create the magnetic fields in devices such as transformers and induction motors.
The Power factor of a utility depends on the type of load it supplies. Usually the Loads on utility are inductive loads (where the current lags behind the Voltage) and hence the power factor at which the utility operates is lagging. Most loads connected to utility are inductive loads like motors, fans, rolling mills which cause the power factor of the utility to be of lagging in nature.
How you check the elcb is working or not?
By simulating a earth leak on the device connected to ELCB. A short between phase and the body or earth point. Care must be taken. It must be done by a trained Electrician only. It is dangerous to do it.
Why Fuel consumption varying when the generator load varies?
with decrease in fuel consumption the amount of steam produced is also reduced.Hence when lower quantity of steam passes through the turbine the torque generated is less and since generator and turbine are coupled on a single shaft the generator torque also decrease which reduces load.
Is the larger a parallax shift the closer an object is?
Yes, that's the way it works. A parallax angle of 1" (arc-second) means that the object is at a distance of 1 parsec (that's how the parsec is defined); at a parallax angle of 1/10 of an arc-second, the object would be at a distance of 10 parsec, etc. A parsec is approximately 3.26 light-years.
An ideal voltage source charges capacitor in?
A: A voltage source Will charge a capacitor to 63% of its input value, The value to get there is stated a Resistance time capacitor as time. Mathematically it will never get there but engineering consider 5 times RC time constant as close enough,
