Name of the College : SARASWATHI VELU COLLEGE OF ENGINEERING
University : Anna University
Subject Code/Name : EE2352/Solid State Drives
Degree : B.E
Sem : VI
Website : svcoe.ac.in
Document Type : Question Bank
Download Model Question Paper : https://www.pdfquestion.in/uploads/svcoe.ac.in/3388-EE2352.pdf
SVCOE Solid State Drives Question Paper
Two Marks Questions and Answers :
Solid State Drives (EE2352) S6 EEE
1. What is meant by electrical drives?
Systems employed for motion control are called drives and they employ any of the prime movers such as diesel or petrol engines, gas or steam turbines, hydraulic motors and electric motors for supplying mathematical energy for motion control. Drives employing electric motion are called electric drives
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2. Mention the different types of drives.
1)Group drive
2)Individual drive
3)Multimotor drive
3. List the different types of electrical drives.
1)dc drives
2)ac drives
4. What are the advantages of electric drives?
1) They have flexible control characteristics. the steady state and dynamic characteristics of electrical drives can be shaped to satisfy load requirements.
2) Drives can be provided with automatic fault detection systems, programmable logic controllers and computers can be employed to automatically ctrl the drive operations in a desired sequence.
3) They are available in which range of torque, speed and power.
4) It can operate in all the four quadrants of speed-torque plane. Electric braking gives smooth deceleration and increases life of the equipment compared to other forms of braking.
5) Control gear required for speed control, starting and braking is usually simple and easy to operate.
5. Mention the different factors for the selection of electric drives?
1) Steady state operation requirements.
2) Transient operation requirements.
3) Requirements related to the source.
4) Capital and running cost, maintenance needs, life.
5) Space and weight restriction.
6) Environment and location.
7) Reliability.
6. Mention the parts of electrical drives.
1) Electrical motors and load.
2) Power modulator
3) Sources
4) Control unit
5) Sensing unit
7. Mention the applications of electrical drives
Paper mills
Electric traction
Cement mills
Steel mills
8. Mention the types of enclosures
Screen projected type
Drip proof type
Totally enclosed type
Flame proof type
9. Mention the different types of classes of duty
Continuous duty
Discontinuous duty
Short time duty
Intermittent duty
10. Define equivalent current method
The motor selected should have a current rating more than or equal to the current. It is also necessary to check the overload of the motor. This method of determining the power rating of the motor is known as equivalent current method.
11. Define cooling time constant
It is defined as the ratio between C and A. Coolng time constant is denoted as Tau
Tau = C/A
Where C=amount of heat required to raise the temp of the motor body by 1 degree Celsius
A=amount of heat dissipated by the motor per unit time per degree Celsius.
12. What are the methods of operation of electric drives?
Steady state
acceleration including starting
deceleration including starting
13. Define four quadrant operation.
The motor operates in two mode: motoring and braking. In motoring, it converts electrical energy into mechanical energy which supports its motion. In braking, it works as a generator, converting mathematical energy into electrical energy and thus opposes the motion. Motor can provide motoring and braking operations for both forward and reverse directions.
14. What is meant by mechanical chars?
The curve is drawn between speed and torque. This characteristic is called mechanical characteristics.
15. Mention the types of braking
Regenerative braking
Dynamic braking
Plugging
16. Define and mention different types of braking in a dc motor?
In braking the motor works as a generator developing a negative torque which opposes the motion. Types are regenerative braking, dynamic or rheostat braking and plugging or reverse voltage braking.
17. List the drawbacks of armature resistance control?
In armature resistance control speed is varied by wasting power in external resistors that are connected in series with the armature. since it is an inefficient method of speed control it was used in intermittent load applications where the duration of low speed operations forms only a small proportion of total running time.
18. What is static Ward-Leonard drive?
Controlled rectifiers are used to get variable d.c. voltage from an a.c. source of fixed voltage controlled rectifier fed dc drives are also known as static Ward-Leonard drive.
19. What is a line commutated inverter?
Full converter with firing angle delay greater than 90 deg. is called line commutated inverter. such an operation is used in regenerative braking mode of a dc motor in which case a back emf is greater than applied voltage.
21. Write the expression for average o/p voltage of full converter fed dc drives?
Vm=(2Vm/pi)cospi……………..continuous conduction
Vm=[Vm(cos alpha-cos beta)+(pi+alpha+beta)]/pi]……..discontinuous conduction
22. What are the disadvantages of conventional Ward-Leonard schemes?
Higher initial cost due to use of two additional m\cs.
Heavy weight and size.
Needs more floor space and proper foundation.
Required frequent maintenance.
Higher noise and higher loss.
23. Mention the drawbacks of rectifier fed dc drives?
Distortion of supply.
Low power factor.
Ripple in motor current
24. What are the advantages in operating choppers at high frequency?
The operation at a high frequency improves motor performance by reducing current ripple and eliminating discontinuous conduction.
25. Why self commutated devices are preferred over thyristors for chopper circuits?
self commutated devices such as power MOSFETs power transistors, IGBTs, GTOs and IGCTs are preferred over thyristors for building choppers because they can be commutated by a low power control signal and don’t need commutation circuit.
26. State the advantages of dc chopper drives?
Dc chopper device has the advantages of high efficiency, flexibility in control, light weight, small size, quick response and regeneration down to very low speed.
27. What are the advantages of closed loop c of dc drives?
Closed loop control system has the adv. of improved accuracy, fast dynamic response and reduced effects of disturbance and system non-linearities.
28. What are the types of control strategies in dc chopper?
Time ratio control.
Current limit control.