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2nd Period Electrican > Motor control > Flashcards

Motor control Flashcards

1
Q

relays

A

electromagnetic switches control a load

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2
Q

plug in relays

A

general purpose
wire terminal basee
control circuits
10 - 15 amps

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3
Q

induistrial control relays

A

heavy duty
switching control circuits
bridge contacts to reduce arcing that pits and weld
adder decks to increase contacts

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4
Q

power relays

A

direct switching of small motors and heating
not subjected to high cycle rates
30 amps
2hp

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5
Q

low voltage lighting relays

A

lighting systems
less than 30 V
single pole contacts

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6
Q

contactors

A

electromagnetic operated switches for high current
overload protection is seperate

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7
Q

NEMA

A

general purpose
simple
limited

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8
Q

IEC

A

design for life cycle
smaller size

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8
Q

reversing contactors

A

2 non reversing contactors with a mechanical and electromagnetic interlock

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9
Q

mechanically interlocked contactor

A

2 contactors with mechanical interlock

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10
Q

mechanically held contactors

A

latch in
large lighting
reduce power consumption
2 coils one energizes, one deenergizes

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11
Q

definite purpose contactor

A

HVAC
auto thermostat

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12
Q

FORM A

A

SPST NO

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13
Q

FORM B

A

SPST NC

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14
Q

FORM C

A

SPDT

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15
Q

FORM X

A

SPST NO DM

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16
Q

FORM Y

A

SPST NC DB

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17
Q

BIFURCATED CONTACTS

A

DOUBLE THE NUMBER OF CONTACT POINTS
PARALLEL PATHS
REDUCE CONTACT RESISTANCE
INCREASE RELAY SWITCHING RELIABILITY

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18
Q

SHADING COILS

A

CONTINUOUS LOOP OF COPPER EMBEDDED IN ARMATURE
SEALS IN ARMATURE
MINIMIZES CHATTERING

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19
Q

CONTACT MATERIALS

A

SILVER LOW VOLTAGE APPLICATION SELF CLEANING CAN BE WELDED
COPPER HIGH VOLTAGE HARD SURFACE HIGH PRESSURE PRONE TO OXIDATION
CADMIUM PLATED FREQUENT SWITCHING STRONG SPRING TENSION LONG LIFE NOT AS CONDUCTIVE

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20
Q

CONTACT SPRING

A

ABSORB SHOCK OF CLOSING
MAINTAIN PRESSURE

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21
Q

ARMATURE SPRING

A

PUSHES ARMATURE OPEN ON DEENERGIZATION

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22
Q

INCORRECT SPRING TENSION

A

INCREASE RESISTANCE
CONTACT BOUNCE
EXCESSIVE ARCING

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23
Q

SEAL IN VOLTAGE

A

85% RATED VOLTAGE

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24
Q

DROP OUT VOLTAGE

A

50% RATED VOLTAGE

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25
Q

COIL CURRENT BEFORE SEAL IN ARMATURE

A

4 -10 TIMES HIGHER

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26
Q

HIGH COIL VOLTAGE

A

VIOLENT SNAP IN
DAMAGE TO CONTACSTS
NEVER 110% MORE

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27
Q

LOW COIL VOLTAGE

A

CONTACTS DONT CHANGE
COIL BURN OUT
CHATTERING
ARCING
PITTING HIGHER RESISTANCE

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28
Q

SHORT CIRCUIT

A

GROUND FAULT
LINE TO LINE FAULT

29
Q

OVERLOAD CONDITION

A

OVER NORMAL CIRCUIT CURRENT

30
Q

FUSES

A

SHORT LENGTH OF CONDUCTOR
PASSIVE CARRY NORMAL LOAD
ACTIVE OPEN CIRCUIT UNDER ABNORMAL CONDITION

31
Q

NON TIME DELAY FUSE

A

SINGLE ELEMENT FUSE
IMMEDIATE

32
Q

TIME DELAY FUSE

A

DUAL ELEMENT (THERMAL CUTOUT, FUSE ELEMENT)
INVERSE TIME
500%

33
Q

INSTANTANEOUS CIRCUIT BREAKERS

A

SHORT CIRCUIT OVER-CURRENT CONDITIONS
ELECTROMAGNETIC COMPONENT SENSE INCREASE IN MAGNETIC FIELD

34
Q

THERMAL MAGNETIC CIRCUIT BREAKER

A

TIME LIMIT CIRCUIT BREAKER
OVERCURRNT PROTECTION
SHORT CIRCUIT PROTECTION
INVERSE TIME

35
Q

TRIP FREE MECHANISM

A

TRIPS EVEN IF HELD IN ON POSITION

36
Q

MOTOR PROTECTION

A

OVERCURRENT DEVICE
OVERLOAD PROTECTION DEVICE

37
Q

tHERMAL OVERLOAD DEVICE

A

SOLDER POT
BIMETALLIC STRIP

38
Q

FUSE CHARACTERISTICS

A

FAST BLOW (NORMAL AND ULTRA)
SLOW BLOW
TIME DELAY
HALF CYCLE

39
Q

OVERCURRNET DEVICE RATING

A

CONTINUOUS NORMAL
INTERRUPTING MAXIMUM SAFELY OPEN

40
Q

FAULT CURRENT VALUES

A

CIRCUIT VOLTAGE
IMPEDANCE OF SHORT CIRCUIT PATH
kVA OF SUPPLY TRANSFORMER
PERCENT IMPEDANCE OF TRANSFORMER

41
Q

FUSED DISSCONNECT

A

FUSES FOR OVERCURRENT PROTECTION
DISCONNECT UNGROUNDED CONDUCTORS

42
Q

FULL LOAD AMPERES

43
Q

MOTOR CHARACTERISITCS

A

JOGGING LOWER THAN CONTINUOUS

44
Q

NEMA SIZE

45
Q

IEC SIZE

A

AC-1 TO AC-4

46
Q

FACTORS FOR MOTOR HEATING

A

MAGNITUDE OF LOAD
DURATION OF OVERLOAD
HOW OFTEN MOTOR STARTS
TIME TAKEN TO GET TO SPEED
AMBIENT TEMPERATURE
COOLING ABILITY
DUTY CYCLE

47
Q

SINGLE PHASING

A

LOSS OF ONE PHASE OUT OF THREE
LOOSE CONNECTION
BREAK IN MOTOR SUPPLY OR MOTOR WINDING
BLOWN FUSE
BURNT OUT CONTACT

48
Q

SERVICE FACTOR

A

1.15 = 1.25
<1.15 =1.15

49
Q

MELTING ALLOY OVERLOAD DEVICE

A

SOLID TO LIQUID
RESET BY HAND
AFFECTED BY AMBIENT TEMPERATURE
TAMPER PROOF
NOT AFFECT BY VIBRATION
REACTS TO SINGLE PHASING

50
Q

BIMETALLIC STRIP OVERLOAD DEVICE

51
Q

3 PHASE BIMETALLIC STRIP OVERLOAD

A

AUTO COMPENSATE FOR AMBIENT TEMP
ADJUSTABLE
MORE PRECISE

52
Q

LOW VOLTAGE PROTECTION

A

3 WIRE
MANUAL RESTART

53
Q

LOW VOLTAGE RELEASE

A

2 WIRE CONTROL
AUTO RESTART

54
Q

NEMA NUMBERING

A

2 3 FWD HOLDING CONTACTS
4 5 REV HOLDING CONTACTS
6 FWD CONTACTOR
7 REV CONTACTOR

55
Q

IEC NUMBERING

A

13 14 HOLDING CONTACTS
A1 A2 CONTACTORS
95 96 OVERLOADS

56
Q

SERIES FIXED RESISTANCE

A

CENTER HOT
2 ENDS COLD
CUSTOM ORDER
SPECICIF LENGTHS

57
Q

POLYMER INSULATED

A

ONE CONDUCTOR 2
CONDCUCTOR 1 END
3 CONDUCTOR 1 END
3500M

58
Q

PARALLEL FIXED RESISTANCE

A

CONSTANT WATTAGE SYSTEM
CUT TO LENGTH

59
Q

SELF REGULATING VARIABLE RESISTANCE

A

CHANGES RESISTANCE WITH TEMPERATURE
INVERSE REALTIONSHIP

60
Q

SKIN EFFECT HEAT TRACING

A

CURRENT FLOWS ONLY ON INSIDE OF FERROMAGNETIC TUBE
WELDED TO PIPE
HIGH VOLTAGE
GROUNDED 3 TO 15 KM

61
Q

SOFT START

A

GRADUAL RISE IN VOLTAGE

62
Q

INTERVAL TIMING

A

CHANGES CONDITIONS OF TIMED CONTACTS IMMEDIATELY
STAY CHANGED UNTIL A TIME PERIOD

63
Q

ONE SHOT

A

TIMING FUNCTIONS BEGINS EACH TIME START TERMINAL RECIEVES A SIGNAL

64
Q

REPEAT CYCLE TIMING

A

REGULAR ON AND OFF CYCLE

65
Q

TDOE

A

TIME DELAY ON ENERGIZATION

66
Q

TDOD

A

TIME DELAY ON DEENERGIZATION

67
Q

SECTIONS FOR INTERLOCK CIRCUITS

A

GENERAL STOP
FWD STOP
FWD START
FWD HOLDING
REV STOP
REV START
REV HOLDING

68
Q

PUSHBUTTON INTERLOCKING

2nd Period Electrican (4 decks)

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