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To limit the operating temperature an electrical machine should have proper current rating.

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Description :

Electrical specifications with values for washing machine. 

Answer :

1. Type: Top loading / Front loading type 2. Capacity range: 6kg to 15kg 3. Motor Used: Induction motor 4. Input voltage: 100V- 240V 5. Power: in 1200W / Output power 100–400W{can go upto 1000W) 6. Efficiency: Max efficiency 31% 7. Wattage: 2.100-2.400 W 8. Current: 13A 9. Frequency: 50hz

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56 views 1 answer
Description :

The steady state stability limit as compared to the transient state stability limit is always

Answer :

The steady state stability limit as compared to the transient state stability limit is always Greater

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Description :

Answer :

The operating speed of a synchronous motor can be changed to new fixed value by changing frequency.

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Description :

Which of the following statements is true?  (1) steady-state stability limit is greater than transient stability limit  (2) steady-state stability limit is equal to transient stability limit  (3) steady-state stability limit is less than the transient stability limit  (4) no generalization can be made regarding the equality or otherwise of the steady-state stability limit and transient stability limit

Answer :

Which of the following statements is true?  (1) steady-state stability limit is greater than transient stability limit  (2) steady-state stability limit is equal to transient ... made regarding the equality or otherwise of the steady-state stability limit and transient stability limit

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1.4k views 1 answer
Description :

Write down the basic parts of a lathe machine with their proper functions. 

Answer :

Important Parts of Lathe and their Functions 1. Bed It is the main body of the machine. All main components are bolted on it. It is usually made by cast iron due to its high compressive strength and ... carriage on bed. 12. Spindle: It is the main part of lathe which holds and rotates the chuck.

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Description :

Answer :

Synchronsizing power of a synchronous machine is inversely proportional to the synchronous reactance.

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Description :

Answer :

A synchronous machine with low value of short-circuit ratio has lower stability limit.

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Description :

If we change the excitation of synchronous machine will it affect on power factor?

Answer :

Yes, If we change the excitation of synchronous machine it will affect on power factor. If the synchronous motor is overexcited then it will have leading power factor and if the motor is underexcited then it will have lagging power factor.

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88 views 1 answer
Description :

If we change the excitation of synchronous machine will it affect on motor speed?

Answer :

No, If we change the excitation of synchronous machine it will not affect on motor speed.

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80 views 1 answer
Description :

V - curve of synchronous machine shows the relation between?

Answer :

V - curve of synchronous machine shows the relation between AC armature current and DC field current.

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65 views 1 answer
Description :

Why synchronous machine is called doubly excited machine?

Answer :

Armature windings of synchronous machines either deliver 3 phase AC or absorb 3 phase AC source,  whereas field windings are energized from DC source. Thus due to presence of AC on armature and DC on field windings, synchronous machines are often referred as doubly excited machines.

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Description :

Which machine is the exciter of synchronous machine?

Answer :

DC shunt machine is the exciter of synchronous machine.

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55 views 1 answer
Description :

An electrical circuit with 10 branches and 7 junctions will have

Answer :

An electrical circuit with 10 branches and 7 junctions will have  4 loop equations.

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Description :

Answer :

The efficiency of transformer is Greater than electrical Machine because there is no rotational losses in transformer and there is no air gap losses in transformer so losses is less in transformer compare to electrical machine so efficiency is higher in case of transformer.

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Description :

The command line interpreter that enables the users to interact with operating system is called the A) Window B) Shell C) Process D) Kernel 

Answer :

The command line interpreter that enables the users to interact with operating system is called the Shell 

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69 views 1 answer
Description :

A minimum clearance of 6.3 m to ground is required for overhead lines when operating voltages are :  (A) less than 66 kV (B) lie between 66 kV and 110 kV (C) more than 165 kV (D) lie between 110 kV and 165 kV

Answer :

A minimum clearance of 6.3 m to ground is required for overhead lines when operating voltages are : lie between 66 kV and 110 kV

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115 views 1 answer
Description :

In order to have a lower cost of electrical energy generation the load factor  (1) and the diversity factor should be low (2) should be low but the diversity factor should be high (3) should be high but the diversity factor should be low (4) and the diversity factor both should be high

Answer :

In order to have a lower cost of electrical energy generation the load factor and the diversity factor both should be high

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Description :

A certain power MOSFET has a maximum junction temperature specification of 1500o C, a junction-to-case thermal resistance of 1.00 C/W, and a junction-to ambient thermal resistance of 600 C/W. If the ambient temperature is 300o C, then the maximum allowable power dissipation in the device will be A) 1.52 W B) 1.72 W C) 1.92W D) 2.00 W

Answer :

A certain power MOSFET has a maximum junction temperature specification of 1500o C, a junction-to-case thermal resistance of 1.00 C/W, and a junction-to ambient thermal resistance of  ... 300o C, then the maximum allowable power dissipation in the device will be 2.00 W 

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Description :

A _________ is used to measure the stator % winding temperature of the generator.  (A) Thermocouple (B) Pyrometer (C) Resistance thermometer (D) Thermometer

Answer :

A Resistance thermometer is used to measure the stator % winding temperature of the generator. 

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Description :

Answer :

If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor.

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Description :

 operating principle of PUT.

Answer :

Constructional diagram & Operating principle of PUT:  The PUT is a PNPN device similar to SCR, but its operation is similar to the UJT. The PUT behave like a UJT whose trigger voltage VP can be set ... low resistance and VAK ≈ 1V). The PUT is also referred to as a complementary SCR (CSCR). 

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Description :

Transistor operating configurations

Answer :

Transistor operating configurations

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Description :

Draw construction of Megger and write operating principle of it.

Answer :

Megger:  Working: Two coils the current coil and pressure coil are mounted at an angle on the same spindle and form the part of the moving system. These coils are connected to a small hand driven ... . When the instrument is not working the pointer may rest at any position on the dial.

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Description :

Explain the operating principle of LASER and list applications of LASER diode.

Answer :

A basic construction of Laser diode is as shown . A PN junction is formed by two layers of doped gallium arsenide. There is highly reflective surface at one end of PN junction and ... 6. laser scanning and light beam illumination. 7. Military applications 8. Medical surgery 9.Diamond cutting

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Description :

The operating point of a protective current transformer is near the

Answer :

The operating point of a protective current transformer is near the Ankle point

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Description :

The operating time of instantaneous relay is

Answer :

The operating time of instantaneous relay is 0.1 sec

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Description :

In a single-phase induction motor, the operating direction is determined by the ________ A) Rotor B) Stator C) Starting circuit D) None of these

Answer :

In a single-phase induction motor, the operating direction is determined by the Starting circuit

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Description :

What is the power factor when a single phase watt meter operating on 200 V and 5 A for 5 hours makes 2016 revolutions and the meter constant in revolution is 420? A) 0.04 B) 1.04 C) 0.96 D) None of these

Answer :

What is the power factor when a single phase watt meter operating on 200 V and 5 A for 5 hours makes 2016 revolutions and the meter constant in revolution is 420? A) 0.04 B) 1.04 C) 0.96 D) None of these

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Description :

The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ (A) directly proportional to α and Φ (B) inversely proportional to α and Φ (C) directly proportional to α and inversely proportional to Φ (D) directly proportional to Φ and inversely proportional to α

Answer :

The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ directly proportional to α and inversely proportional to Φ

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Description :

In a 230 V, 50 Hz single-phase SCR bridge converter operating at a firing delay angle, α and with large R-L load, the input source current is (A) sinusoidal current (B) constant dc current (C) continuous rectangular pulses (D) alternating rectangular pulses

Answer :

In a 230 V, 50 Hz single-phase SCR bridge converter operating at a firing delay angle, α and with large R-L load, the input source current is alternating rectangular pulses

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132 views 1 answer
Description :

Two synchronous generators operating in parallel supply a common load of 2.5 MW. The frequency-power characteristics have a common slope of 1 MW/Hz and the no-load frequencies of the generators are 51.5 Hz and 51.0 Hz, respectively. Then the system frequency is (A) 50 Hz (B) 51 Hz (C) 51.25 Hz (D) 51.5 Hz

Answer :

Two synchronous generators operating in parallel supply a common load of 2.5 MW. The frequency-power characteristics have a common slope of 1 MW/Hz and the no-load frequencies of the generators are 51.5 Hz and 51.0 Hz, respectively. Then the system frequency is 50 Hz

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Description :

A 230 V/460 V single-phase transformer operating at 20 A and unity power factor has primary referred resistance of 0.2 Ω and reactance of 0.5 Ω. The approximate primary induced emf is (A) 216 V (B) 226 V (C) 234 V (D) 236 V

Answer :

A 230 V/460 V single-phase transformer operating at 20 A and unity power factor has primary referred resistance of 0.2 Ω and reactance of 0.5 Ω. The approximate primary induced emf is 226 V

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Description :

Answer :

Operating torques in analogue instruments are deflecting, control and damping.

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Description :

Answer :

The operating voltage of a meggar is about 100 V.

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Description :

Answer :

Annual operating expenditure of a power plant consists of fixed charges, semi-fixed charges, running charges.

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Description :

Answer :

The relay operating speed depends upon the spring tension, the rate of flux built up, armature core air gap.

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Description :

The secondary of a current transformer is always short-circuited under operating conditions because it?

Answer :

The secondary of a current transformer is always short-circuited under operating conditions because it avoids core saturation and high voltage induction.

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Description :

For a transformer, operating at constant load current, maximum efficiency will occur at?

Answer :

For a transformer, operating at constant load current, maximum efficiency will occur at unity power factor.

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96 views 1 answer
Description :

Operating frequency of power MOSFET is higher than that of power BJT. Justify the statement.

Answer :

Power MOSFET have high turning on and turning off capability high switching speed of MOSFET is due to the high rate of change of drain voltage. The switching losses of power MOSFET ... lower frequency. Hence, operating frequency of power MOSFET is higher than that of power BJT.

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Description :

Answer :

Active , Saturation , Cut-off region of operations in BJT.

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Description :

Explain the suitability of aluminium as an electrical conductor with respect to its mechanical and electrical properties. 

Answer :

Following are requirements of conductor:- i) High conductivity :  Material should have high conductivity, So that * cross section of conductor (size) reduces, * Copper losses reduces, * So Efficiency ... . Boiling point is 1820°C 9. Specific gravity is 2.7 10. High resistance to corrosion. 

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102 views 1 answer
Description :

A circuit breaker is designed to protect an electrical circuit from damage caused by :  (A) Over load (B) Short circuit (C) Over current (D) All of the above

Answer :

A circuit breaker is designed to protect an electrical circuit from damage caused by :  (A) Over load (B) Short circuit (C) Over current (D) All of the above

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87 views 1 answer
Description :

Power factor of an electrical circuit is equal to?

Answer :

Power factor of an electrical circuit is equal to R/Z, cosine of phase angle difference between current and voltage, kW/kVA.

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225 views 1 answer
Description :

State the insulating materials used in motor. Write temperature class and withstand temperature ranges for them. 

Answer :

The insulating materials used in motor are as belows: 1. Cotton, 2. Silk, or paper, 3. Press board, 4. Resins 5. PVC 6. Cellulose-Fiber, 7. Enameled coating, etc  ... Over 180° Mica, porcelain, ceramics, glass quartz, asbestos, treated glass fiber or treated asbestos. etc.

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72 views 1 answer
Description :

State two applications of : (i) PVC paper (ii) Porcelain with type of class based on withstand temperature is insulating material. 

Answer :

 (i) Application of PVC paper : 1. It is used in slot lining or motor winding insulation purpose 2. For Insulation of Transformer winding (ii) Application of Porcelain : 1. Mainly used for manufacturing ... on withstand temperature : * H' & C' Class of insulation i e. 180° and above 180°C 

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125 views 1 answer
Description :

Design a temperature detecting circuit  assuming a linear temperature (T, in degree Celsius) detecting signal in Voltage (mV)  V = 0.2 + 0.1 * T  T is from 10 (oC) to 80 (oC)  Design an amplifying circuit based on MOSFETs.  Output voltage should be larger than 0.5V  The output voltage should be linear with ... you show detail about how to detect the temperature, how the circuit work, restriction,...  really need the PSPICE circuit and how to simulation.  Thank you so much!

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40 views 0 answers
Description :

Temperature controller using SCR

Answer :

Temperature controller using SCR The temperature control circuit is used to regulate the temperature. Figure shows the temperature control circuit using thermostat as temperature detector and SCR as ... half-cycle and heater gets connected to source to produce heat and raise the temperature.

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178 views 1 answer
Description :

Describe the effects of temperature on conductivity of metals.

Answer :

For metallic conductors, the resistance of all pure materials increases linearly with temperature over a limited range of temperature hence conductivity decreases. For metallic conductors, ... vibrating ions collide with the moving electrons. Hence resistance increases with increasing temperature.

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47 views 1 answer
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