Relays And Contractors

Front 1

basic relay categories are

Back 1

plug in relays

industrial control relay

power relay

low voltage lighting relays

Front 2

plug in relays are also known as

Back 2

general purpose relays

Front 3

plug in relays are usually rated for

Back 3

10-15 amps they can also be used for motor loads under 1/2 hp

Front 4

there are 2 pin arrangements

Back 4

spade and tubular

Front 5

describe spade arrangment

Back 5

5-14 spade pins in rows and columns

Front 6

describe tubular pins

Back 6

8-11 tubular pins arranged in a circle

Front 7

how many pins for NO/NC contacts

Back 7

3

Front 8

how many pins for an operating coil

Back 8

2 or 3

Front 9

a latched relay has 2 operations

Back 9

1 change the position of thecontacts one way

2 change the position of the contacts back again

Front 10

a latch relay will

Back 10

stay latched to a position even when de energized

Front 11

latching relay may have 1 or 2 operating coils why

Back 11

one to latch the contacts and another to reset them

Front 12

when are industrial relays needed

Back 12

where reliability and longevity are critical

Front 13

where do you terminate for industrial relays and what are the terminations called

Back 13

terminate on the relay the NO is called double make and NC for double break

Front 14

industrial relays can be customized how

Back 14

with adder decks to contain additional contacts

as well as additional timers and latches can be installed

Front 15

power relays get used for

Back 15

direct switching of small motors and heaters NOT subject to a high cycle rate

Front 16

power relays are rated for

Back 16

2 hp and 30 amps

Front 17

low voltage lighting relays are also called

Back 17

low voltage systems

Front 18

low volt relays operate at

Back 18

less than 30v

Front 19

a low volt relay is designed for use with

Back 19

switches and panels from that manufacturer

Front 20

pilot devices are

Back 20

push buttons

float switches

pressure switches

limit switches

thermostats

Front 21

two manufacturers are

Back 21

nema and IEC

Front 22

NEMA is for

Back 22

simplicity

Front 23

IEC are known for being

Back 23

smaller with a smalller creepage path

Front 24

reversing contactors are

Back 24

an assembly of two non reversing contactors with a mechanical and electrical interlock

Front 25

when an overload block is added the assembly is called

Back 25

reversing motor starter

Front 26

non reversing contactors have how many switching terminals

Back 26

3 main switching terminals

Front 27

mechanically interlocked contactors mounted where

Back 27

side by side in a control box

Front 28

mechanically interlocking them is to

Back 28

prevent both from operating at the same time

Front 29

nameplates on a relay include

Back 29

rating for operating the coil

rating for the coil contacts

style and arrangement

contact terminal mumbering

Front 30

the coils rating is

Back 30

not usually included because the current draw is small. but the relay is coil is relevant to the voltage of the circuit

Front 31

depending on what a contact controls what ratings may be on the relay

Back 31

1voltage

2current rating for continuous use general use non inductive or resistive loads

3hp rating at various voltages

4 nema pilot duty rating

5 IEC classifacation

Front 32

forms are

Back 32

names for industrial relays

like form a

form b... ext

Front 33

review pg 11,12,15

Back 33

its short

Front 34

bifurcated contacts have

Back 34

multiple paths to lower resistance

Front 35

laminations help reduce

Back 35

eddie currents

Front 36

the shading coil dose what

Back 36

prevents chattering noise and its arcing and heating

Front 37

review pg 21 about shading coils

Back 37

ghdjg

Front 38

read the chart of contact material pg 23

Back 38

pg 23

Front 39

the sooner a contact closes means

Back 39

less arcing and longer life

Front 40

contact bounce is

Back 40

the contact closing hard enough to bounce causing a second arc

Front 41

review pg 26

Back 41

g

Front 42

proper relay spring tension helps

Back 42

1keep contacts apart

2holding them together

3opening them fast enough

4closing firm but gently to prevent bouncing

Front 43

why is a wiping action used

Back 43

to keep arcing on the tips on the contacts and self cleans the faces

Front 44

bridge type contact arrangements are good for

Back 44

provides good contact and a wiping action

Front 45

a relay is a manually operated switch t or f

Back 45

false is a electrically operated

Front 46

what is the seal in voltage or pick up voltage

Back 46

usually 85% of the rated voltage

Front 47

the drop out voltage is

Back 47

it varrys with design but it is about 50% of the rated coil voltage

Front 48

after armature seals the current

Back 48

drops

Front 49

when the air gap is closed the resistance

Back 49

increases

Front 50

the current before a armature closes can be

Back 50

4 to 10 times higher

Front 51

insulation breakdown from exceeding voltage rating can cause a

Back 51

short

Front 52

an overly high voltage can cause a lower rated relay to

Back 52

snap violently

Front 53

a supplied voltage shall never be more than

Back 53

110% of its rating

Front 54

during a lower than rated voltage the current drawn could be

Back 54

up to 10 times greater than seal in value

Front 55

review pg 33

Back 55

chart

Front 56

is armature is blocked what will happen to the coil

Back 56

probably burn out

Front 57

when supply is cut off is armature dose not drop out what would be responsible

Back 57

residual magnetism

contacts welded

or jammed