Single Pole Single Throw Relay

Single Pole Single Throw Relay an electromagnetic switch, consist of a coil (terminals 85 & 86), 1 common terminal (30), and one normally open terminal (87). It does not have a normally closed terminal like the SPDT relay, but may be used in place of SPDT relays in all diagrams shown on this site where terminal 87a is not used.

Dual Make SPST Relay  :

Single Pole Single Throw Relay an electromagnetic switch, consist of a coil (terminals 85 & 86), 1 common terminal (30), and two normally open terminals (87 and 87b). Dual make SPST relays (Figure 4) are used to power two circuits at the same time that are normally isolated from each other, such as parking lamp circuits on German automobiles. 

The diagram below center (Figure 5) shows a dual make SPST relay at rest, with the coil not energized. The diagram below right (Figure 6) shows the relay with the coil energized. The coil is an electromagnet that causes the arms that are always connected to the common (30) to pivot when energized whereby contact is made with the normally open terminals (87 and 87b). 
 

Diodes are most often used across the coil to provide a path for current when the current path to the relay is interrupted (i.e. switched off, coil no longer energized). This allows the coil field to collapse without the voltage spike that would otherwise be generated. The diode protects switch or relay contacts and other circuits that may be sensitive to voltage spikes. (JimR, contributor, install bay member)

Single Pole Double ThrowRelay

 Single Pole Double ThrowRelay an electromagnetic switch, consist of a coil (terminals 85 & 86), 1 common terminal (30), 1 normally closed terminal (87a), and one normally open terminal (87) (Figure 1). When the coil of an SPDT relay (Figure 1) is at rest (not energized), the common terminal (30) and the normally closed terminal (87a) have continuity. When the coil is energized, the common terminal (30) and the normally open terminal (87) have continuity. 

The diagram below center (Figure 2) shows an SPDT relay at rest, with the coil not energized. The diagram below right (Figure 3) shows the relay with the coil energized. As you can see, the coil is an electromagnet that causes the arm that is always connected to the common (30) to pivot when energized whereby contact is broken from the normally closed terminal (87a) and made with the normally open terminal (87). 

When energizing the coil of a relay, polarity of the coil does not matter unless there is a diode across the coil. If a diode is not present, you may attach positive voltage to either terminal of the coil and negative voltage to the other, otherwise you must connect positive to the side of the coil that the cathode side of the diode is connected and negative to side of the coil that the anode side of the diode is connected. 

UEE BITS

UEE BITS

1.       The motor having wider range of speed control is__________________

2.        For quick reversal the motor preferred is_____________________

3.       In sewing machine the motor is preferred is __________

4.       Which motor is generally used in rolling mills, paper and cements industries___________

5.       The drive motor for large rice mill would be__________

6.       Which motor is most commonly used in refrigerator_____________

7.       The  driver motor for a locomotive would be__________

8.       A pony motor is used for starting a_______________

9.       The motor used in elevator is__________

10.   Galvanizing is the process of applying a layer of__________

11.   Current range for arc welding is usually__________

12.   Electric welding produces temperature up to _____________

13.   Electronic components are joined by___________

14.   Because of high leakage reactance, the induction furnace works on__________

15.   Coreless induction furnaces are operated at_________

16.   For measuring temperature of electric finance the instrument used is____

17.   In a core less furnace, low current density prevents effect in the molten material__________

18.   Immersion water heater comes under?

19.   Annealing of material is performed by?

20.   If “f” is the supply frequency in high frequency induction type heating. The  depeth of penetration of heat is proportion to_______

21.   To produce a good weld the voltage across arc should be around_______

22.   A condenser is provide in tube light to___________

23.   The colour of light depend up on ___________

24.   Units Luminous intensity?

25.   Unit of luminous flux?

26.   The colour of sodium oxide vapour lamp is____________

27.   Mercury vapour at high pressure gives a colour of__

28.   Mercury vapour at low pressure gives a colour of_______

29.   In an incandescent lamp the filament material is made of______

30.   The gas used in a high pressure mercury vapour lamp is______

31.   The gas used in sodium vapor lamp is______

32.   Some times the rotating devices, in a room having fluorescent lamps, appear to be stationery. This is due to

33.   For regenerative braking, the regenerated power should have_________

34.   Contact with wire is maintained by__

35.    Quadrilateral speed time curves is used for_______

36.   The dc motor speed control method which gives the speed above rated speed____

37.    The dc motor speed control method which gives the speed below rated speed____

38.   The drive used in textile mills­­­­­­__________

39.   The drive used in cement mills____________

40.   The drive used in coal mills__________

41.   During regenerative braking energy is____

42.   The voltage used for Ac traction in INDIA is_____

43.   Which motor is a not self starting motor________

44.    In Xerox machine, the motor used is________

45.   The important application of scharge motor____

46.   The over efficiency of steam loco motive is_____

47.   The friction at the track is _____________

48.   The adhesive weight is more for________

49.    We can save energy during in which mode (braking)?

50.   The area under the speed time curve is?

UEE BITS

1.       Dc shunt motor

2.       Dc motor

3.       Universal motor

4.       Three phase synchronous motor

5.       Squirrel cage induction motor

6.       Squirrel cage induction motor

7.       Dc series motor

8.       synchronous motor

9.       3-ph induction motor

10.    Lead

11.   15 to 75 A

12.   3600^o

13.   Brazing

14.   Lagging p.f

15.   High frequency

16.   Pyrometer

17.   Pinching effect

18.   Indirect resistance heating

19.   Resistance heating

20.   1/f

21.   10 volts

22.   To improve p.f

23.   Wave length & frequency

24.   Candela

25.   Lumen

26.   Yellow

27.   Bluish white

28.   Bluish green

29.   Tungsten

30.   Argon

31.   Neon

32.   Stroboscopic effect

33.   The same frequency as that of the main supply

34.   Pantograph collectors along with springs & bow

35.   Urban services

36.   Field resistance method

37.   Armature resistance method

38.   Squirrel  cage 

39.   Slip ring IM

40.   Dc motors

41.   Returned to supply lines

42.   25 kv

43.   Squirrel cage IM

44.   Universal motor

45.   Rolling mills 

46.   15-35%

47.   Inversely proportional to speed

48.   Diesel traction

49.   Regenerative braking

50.   Schedule speed

POWER SYSTEM OPERATION AND CONTROL

1)    When the generating units in power plant are loaded with equal incremental costs then what will be cost of generation?

2)    When will the cost of generation decrease?

3)    What can we derive from the incremental curve for thermal generation?

4)    The optimal loading of generators corresponding to equal incremental cost point of all the generators. What is the equation called?

5)    What will happen to generator if the power demand increases suddenly?

6)    Which is the type of generation station with minimum running cost?

7)    What is the general form of fuel cost equation?

8)    The practical derivative dP_i =dPG_i is referred as?

9)    What is the equation by which the loss coefficient B₁₂  can be calculated?

10)                       Express incremental fuel cost.

11)                       Express the cause that provides steady state power output setting for the turbine.

12)                       Express the equation in terms of generation and B_mn  coefficientsin the transmission loss a two plant system.

13)                       What will be the value of the incremental loss for equal incremental cost for all plants?

14)                       Express the term ‘Penalty factor’.

15)                       The electric company has to decide in advance which generator to start up and when to connect them to network and the sequence in which the operating units be shut down and for how long. This computational procedure is called by the term?

16)                       The minimum demand that always exist on the system is called by the term?

17)                       What is an isolated system?

18)                       What is ALFC?

19)                       An extended power system can be divided into a number of load frequency control areas. What is the term used for inter connection?

20)                       The power flow between lines A and B by te line is given by equation?

21)                       What is ACE?

22)                       If all generators respond in unison then this is called?

23)                       What is the relation between kinetic energy and the speed of the generator?

24)                       What is the change in frequency of t he integral control area of the system?

25)                       What are the factors on which the system damping strongly depends?

26)                       When is the synchronizing power maximum?

27)                       In how many ways the position of pilot value can be effected via the linkage system?

28)                       What is the relation between two tie line powers if the areas are identical?

29)                       What is the damping coefficient formula?

30)                       What is the relation between T_g , T_t , T_p ?

31)                       What are the units for static frequency?

32)                       The speed changer has fixed setting and the load demand changes this is known as?

33)                       What is the range of turbine time-constant?

34)                       What is the synchronizing coefficient between two areas of power system?

35)                       What is the relation between frequency and the load angle?

36)                       What is ‘swing equation’?

37)                       What is the necessity of keeping the frequency of an alternator constant?

38)                       What is a synchronous condenser?

39)                       Which type of generation has maximum efficiency?

40)                       Which type of generation has maximum air pollution?

41)                       What is meant by ‘SCADA’?

42)                       The equation synchronizing coefficient between two generators?

43)                       What for series capacitor are used on transmission line?

44)                       What is the condition for uncontrolled case in a two area system?

45)                       What is the effect of series capacitor in a transmission line?

46)                       What is the effect of shunt capacitor at load bus?

47)                       Which of the compensator directly improve system load ability?

48)                       The value of penalty factor is?

49)                       What is the unit of speed regulation?

50)                       What is the unit of heat rate?

POWER SYSTEM OPERATION AND CONTROL  KEY

1)    Minimum

2)    When the load factor increases

3)    Fuel cost in Rs/hr

4)    Co ordination

5)    Frequency  will decrease

6)    Hydro electric

7)    (½)aPG_i²+bPG_i+d

8)    Incremental transmission losses

9)   

10)                       aPG_i+b

11)                       speed changer

12)                       B₁₁P₁²+B₂₂P₂²+2B₁₂P₁P₂

13)                       Zero

14)                       L_i =

15)                       Unit commitment

16)                       Base load

17)                       A single turbo generator supplying an isolated load

18)                       Automatic load frequency control

19)                       Tie-lines

20)                       P_AB =

21)                       Area control error

22)                       Control are

23)                       K.Ef²

24)                       Zero

25)                       f⁰ and H

26)                       no load

27)                       3 ways

28)                       P_tie1= -P_tie2

29)                       D=

30)                       T_g < T_t <T_P

31)                       HZ

32)                       Free governor operation

33)                       0.2 to 2 sec

34)                      

35)                      

36)                      

37)                      

38)                       An over excited synchronous motor

39)                       Hydro power

40)                       Steam power plant

41)                       Supervisory control and data acquisition system

42)                       T₁₂ =

43)                       To compensate for line inductive reactance

44)                      

45)                      

46)                       Improve system voltage

47)                       Series capacitance

48)                       More than unity

49)                       HZ/MW

50)                       Kcal/KWh