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Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
How is the resistance of a metallic conductor affected by variation in temperature?
In general, pure metal conductors increase in resistance as their temperature increases. This is not necessarily true for alloys, as some alloys are manufactured to have an approximately constant resistance over a wide range of temperatures.
How many lumens output in a 500 watt quartz Halogen bulb?
The bulb will have an efficacy of 17-20Lm per watt, so in total 500W = 8,500-10000 lumens. However, the bulbs light output is non directional, so a lot of the spilled light is in directions that you don't want it to go, so 50-70% of the figure can be used when specing up an LED variant.
What is insulation resistance in capacitor?
ideally there will not be any resistance to the capacitor,so at this condition it should not not discharge the stored energy. but practically small resistance will be there in the capacitor so the energy stored by the capacitor will be discharged through resistance.
The kva rating includes the power factor of the connected load.
KW * Power Factor = kva.
AnswerThe above answer is incorrect, as it's actually kV.A x power factor = kW.
The answer is straightforward, the output of the UPS is the product of its rated output voltage and its rated output current, and the product of voltage and current is 'apparent power', expressed in volt amperes.
What is interpole winding in DC machine?
For a D.C motor it is the field windings which must always be in series with the armature windings.
What is meant by cut off voltage in diode?
Cutoff voltage is the point at which the battery is fully discharged. This is usually the point at which the device will shut itself off.
Does hermetically sealed transformer have a conservator?
no,hermetical transformers do not have conservator.
Explain the term floating earth in portable appliances?
A 'floating ground' (or 'floating earth'), in the context of your question, describes an appliance whose metal enclosure is ungrounded when it is designed to be grounded. This can happen, for example, when the supply cable's ground wire is not connected to the earth pin at a plug, or has become accidentally disconnected at the appliance.
The purpose of grounding an appliance's metal enclosure is to provide a low-resistance path to earth in the event that an internal live conductor should accidentally make contact with that enclosure -thus causing the local overcurrent protective device to disconnect the appliance. If the ground wire becomes disconnected, then this protection will no longer apply, and the appliance becomes a shock hazard.
What is the purpose of auto transformer?
Helps with the starting of large electric motors.
AnswerAn autotransformer is a transformer with a single winding, rather than two separate windings. It can be used as a step-up or as a step-down transformer, provided there is no requirement for electrically-isolating the secondary circuit from the primary circuit.
What are peripheral effects of power electronics equipments?
The operations of power electronic converters are mainly based on the switching of power semiconductor devices. Due to this the converters introduce voltage and current harmonics into the source as well as load. These harmonics can cause problems of distortion in the output voltage and current and also electromagnetic interference with the neighboring systems. To reduce these harmonics to an acceptable level it is necessary to introduce filters on the input and output of the converter. To evaluate the performance of the converter the quality of the waveform (voltage and current) needs to be measured using factors such as total harmonic distortion (THD), harmonic factor (HF) and input power factor (IPF). The implementation of proper control algorithm in the controller, generation of harmonics and distortion in the output waveform can be reduced. The switching of the power devices in power electronic converter can cause radio frequency interference due to electromagnetic radiation as a result gating circuits may generate erroneous control signals. This interference problem can be avoided by the use of grounded shielding.
What is the power of an electrical appliance?
It depends on the appliance. All appliances are required to have a 'nameplate' which contains information on their power and voltage ratings.
As we know that P=VI, and P is a constant value for any particular motor, so if the voltages will drop current will increase so that the product of V and I be the that particular constant value for any particular motor
What is an equipotential surface?
It's a surface over which electric charges are evenly distributed, caused by the mutual repulsion between charges of the same polarity.
What are brushes with reference to DC motors?
Bushes, with reference to DC motors is a brushed DC motor which is a motor that designed to run from a direct current (DC) power source. This type of motor is an internally committed electric motor.
What is applications of earthing?
An earthing system can be defined as the electrical potential of the conductors relative to the EarthÍs conductive system. The choice of earthing method can influence the safety and electromagnetic compatibility of the power supply, and regulations can vary considerably among countries.
How do you define voltage gradient?
A voltage gradient or, more accurately, potential gradient, is the change in electric potential measured between a point of high potential and a point of low potential. It is normally measured with respect to one or other of these two points.
A practical example of a potential gradient can be demonstrated by connecting a variable resistor as a potentiometer. If an external voltage is applied across opposite ends of the potentiometer, then a potential gradient can be observed by connecting a voltmeter between one end of the potentiometer and its wiper terminal, and varying the position of the wiper. As the wiper is moved from one end of the potentiometer to the other, the potential will be seen to fall towards zero.
