Description : Explain what happens if a DC motor is fed with AC supply
Last Answer : Motor will run at low speed, sparking at brushes, heat due to eddy current will finally burn the motor.
Description : How is the speed of a DC motor varied?
Last Answer : To vary the speed of a DC motor we need a constant voltage power supply with a series POT resistor of higher watt rating. A Pulse Width Modulator (PWM) can be used.
Description : Which of the following converts electric energy into mechanical energy: a. Transformer b. DC generator c. Motor d. AC generator
Last Answer : d. AC generato
Description : What do we use for welding on ships? AC or DC?
Last Answer : Ask E/O on your ship.
Description : Why is DC not much in use now?
Last Answer : AC generators are a better technology and voltage transformation (by transformers) is easy is possible in AC and not DC.
Description : Is there phase in DC?
Last Answer : No
Description : The output from a full wave rectifier is (a) A pulsating uni-directional current (b) A DC voltage (c) Zero (d) An AC voltage
Last Answer : a) A pulsating uni-directional current
Description : In a half wave rectifier the rms value of AC component of the waves (a) Zero (b) Equal to DC value (c) More than DC value (d) Less than DC value
Last Answer : b) Equal to DC value
Description : The process of conversion of AC into DC is called (a) Amplification (b) rectification (c) purification (d)magnification
Last Answer : (b) rectification
Description : The only difference between construction of DC generator and Ac generator is that of: a. carbon brush b. Bar magnet c. electromagnet d. Horseshoe magnet
Last Answer : b. Bar magnet
Description : Which component is mainly used in a DC generator: a.slip ring b. commutator c. magnet d. coil
Last Answer : b. commutator
Description : Direct Current (DC) Next Topic : Alternating current (AC)
Last Answer : Direct Current (DC) is the unidirectional electric current. Uni meaning is one. And the flow of charge in same direction. We know that conventional current flow from positive terminal of battery to ... The magnitude of DC may constant or vary but direction do not change with respect to time.
Description : 1.Determine the permeability of magnetic material by plotting its BH curve 2. Measure voltage, current and power in 1-phase circuit with resistive load. 3. Measure voltage, current and ... .Make Star and Delta connection in induction motor starters and measure the line and phase values.
Last Answer : Practical no. 6 Aim: Make Star and Delta connection in induction motor starters and measure the line and phase values. Apparatus required: voltmeter, ammeter, induction motor Circuit diagram ... Result: Hence we have measured the line and phase value of star and delta connection.
Description : What are the parts of a brushless AC generator?
Last Answer : Yoke, armature, stator, rotor, primary exciter, main exciter, rotary diode rectifier assembly, impeller, bearing & housing, end cover, terminal block, AVR.
Description : A wire of uniform area of cross-section A length L and resistance R is cut into two parts. Resistivity of each part a. remains the same b. is doubled c. is halved d. becomes zero
Last Answer : a. remains the same
Description : What are the main electrical equipment used in HPS ? State the function of each parts of it in brief.
Last Answer : Following Main Electrical Equipment used in HPS & their function: 1. Alternator 2. Exciter 3. Transformer 4. Switchgear Function : 1) Alternator:- Alternator is coupled to ... part from the healthy section. It contains circuit breaker, relays, switches and other control devices.
Last Answer : Stepper Motor Such One Kind of Motor Which Equal In the corner Rotation Generated By To whom Step To say Is Since Step by step Step by step Equal In the corner Rotation Creation By So This one Stepper Motor Says.
Last Answer : that Motor AC And DC Both Supply A. Let's go Him Universal Motor Says.
Description : What are the differences between synchronous and induction motor?*
Last Answer : Synchronous motor : Constant speed on all loads, can be operated on a wide range of power factors, not self starting, requires dc excitation.
Description : Where is a rotor wound AC motor used?
Last Answer : For starting heavy torques, mostly used on portable machines and small winches.
Description : What can be possible reasons for a motor failing to start?
Last Answer : No power , Fuse blown , Overload trip, contactor coil burnt , Contactors contacts bad, control circuit relay faulty, stop switch open circuit and start switch does not operate, hold on contact does not make and motor burnt
Description : How can the direction of rotation of an AC motor be reversed?*
Last Answer : By interchanging any two supply lines.
Description : If a motor is wound star and you want to change to delta what should you do?
Last Answer : Open the terminal connection box. Remove the shorting link connecting the common connection (star) point of A2, B2 and C2. With the 3 phase windings marked A1A2, B1B2, C1C2, connect A2 to B1, B2 to C1 and C2 to A1.
Description : How is the speed of a 3-phase induction motor varied?
Last Answer : The speed of a normal 3-phase induction motor is a function of the frequency of the supply voltage. Changing the speed of such a motor hence requires building a 3-phase power frequency ... realised by using power MOSFETs (or IGBTs) capable of handling high voltages and fast switching speeds.
Description : What is a synchronous motor?
Last Answer : A constant-speed motor, the speed being dependent on the frequency of the ac supply and the number of poles for which it is designed.
Description : What is an induction motor?
Last Answer : An induction motor is an alternating current motor in which the primary winding on one member (usually the stator) is connected to the power source and a secondary winding or a squirrel-cage secondary winding on the other member (usually the rotor) carries the induced current
Description : Why are motor ratings given in KW and that of alternator and transformer given in KVA?
Last Answer : kW is the output mechanical power of a motor and is expressed in kW. kVA is the net (apparent) power input to the transformer. This input power is the output + losses. kW = kVA x system power factor
Description : In motor a permanent magnet provides: a. Electric field b. electric flux c. magnetic field d. gravitational field
Last Answer : d. gravitational field
Description : The most common source of AC voltage is: a. motor b. generator c. cell d. transformer
Last Answer : c. cell
Description : The application of mutual induction is: a. TV b. Radio c. Transformer d. Motor
Last Answer : c. Transformer
Description : When a motor is just started, back emf is almost ______: a. Infinite b. zero c. minimum d. maximum
Last Answer : d. maximum
Description : If the motor is overloaded, then the magnitude of ‘back emf’” a. Increases b. Decreases c. Constant d. Becomes zero
Last Answer : Increases
Description : State the need of energy conservation in electrical motor.
Last Answer : Need of energy conservation in Electrical motors: 1. Induction motors are used as electrical drives in industrial, commercial and residential sectors. 2. Considering all industrial applications, 70% of ... system. 8. To adopt advanced technology in design and to use better quality materials.
Description : Describe the following energy conservation methods of electrical motor. i) By motor survey ii) By matching loads with motor rating
Last Answer : Energy conservation methods of electrical motor: 1) By Motor Survey: Large industries have a massive population of LT motors. Load survey of LT motors can be taken-up methodically to ... -speed motors, eddy-current couplings, fluid couplings, and solid-state electronic variable speed drives.
Description : Give two basic speed control scheme of DC shunt motor?
Last Answer : Answer: 1. By using flux control method: in this method a rheostat is connected across the field wdg to control the field current. So by changing the current the flux produced by the field wdg can ... ) can be varied, and since speed is directly proportional to Eb-IaRa the speed can be controlled.
Description : State at least one function and the material used for the following parts of DC Motor.
Last Answer : Part Function Material Yoke -Provides mechanical support for poles -Acts as protecting cover for machine -Provides path for magnetic flux Cast Iron OR Cast Steel Field Winding - ... Pole core Provides mechanical support to field winding. Cast Iron OR Cast Steel
Description : State the function of following parts of DC motor : i) Yoke ii) Poles iii) Field winding iv) Commutator.
Last Answer : Function : i) Yoke: The yoke serves the following two purposes. i) It supports the other components such as poles and provides mechanical protection for whole machine. ii) It forms a part of ... one pole to another and thus to help the motor to develop a continuous and unidirectional torque
Description : Please ripley me due to emergency
Last Answer : To calculate the flux density in the ring, you need to use the following formula: B = (μ * I * N) / (2 * π * r) where: B is the flux density in the ring (in teslas) μ is the relative permeability ... 2 * π * 0.127 m) = 0.53 T So the flux density in the ring would be approximately 0.53 teslas.
Description : Can you help me solve my electrical mystery?
Last Answer : Any signs of animal life? They can get in the walls and chew on the wires. Or is it the entire area served by that breaker? The breaker could be bad. It happens with anything mechanical.
Description : How to tell if a power strip is burned out?
Last Answer : answer:Personally, I would either toss it, or down grade it to outdoor use only. I wouldn’t take a chance with it in the house. Yes, you can let it cool down, then test it again. But a failure is a failure. Does it have a reset button? What price range did you pay?
Description : I accidently soaked an extension cord. Is it safe to use it again after letting it dry out for awhile?
Last Answer : The plug end is easier to dry out than the socket end get out your blow-dryer and set it to high and blow the end that got wet for a while. That will get most of the water off/out of ... up or sputter. Most modern extension cords are pretty watertight so there shouldn't be any water down the wire.
Description : How can a solar array power source be bypassed when the batteries run low?
Last Answer : Ah got it. If anyone else is interested, you need an “automatic transfer switch” – or get a manual one for that mad scientist charm.
Description : How to stop a signal going through a wire?
Last Answer : Use a switch or a variable resistor
Description : Air conditioning will not turn on, is it electrical?
Last Answer : Pull the Thermostat off the wall and see if it is connected correctly to the AC switch. There should be no dangling wires, and the post labeled for the AC should have an attached wire.
Description : What is the speaker driving voltage of an amplifier?
Last Answer : I have to ask WHY? That said, Speakers and a light bulb are two different types of load, and the the lights will probably fry the output transistor.
Description : Why is my Garbage disposal leaking water from the bottom?
Last Answer : Replace it. The seal is leaking, and most cases it is just not worth the cost and work, quicker and cheaper to replace it .
Description : Have you ever taken a shower or bath during an electrical storm?
Last Answer : I’ve heard this rumor, and I too question it’s validity. I mean, if electricity can’t travel up a stream of urine (See mythbusters) I’m pretty sure it couldn’t travel through a shower stream. Perhaps through the drain? In either case, I’ve taken a shower in a storm before, and.. well, you see?
Description : Electrical breaker box is buzzing-why??
Last Answer : No! Do not upgrade the breaker. The wire must also be upgraded if you do. Try plugging it in a different room. Is the problem still there?
Last Answer : Laptop Yes A Portable Computer.
Last Answer : electricity Source , conductor , control Instruments , Usage Machines , Protection Machines In combination Such A Path Whose The middle With Current Flowing To be Can Him Circuit Or Circuit Says.