Motors Part II

Question 1

An ohmmeter reveals one group of three and three groups of two. What kind of motor is this?

Answer 1

Wye

Question 2

What is step one in lead ID for a delta motor?

Answer 2

Find three groups of Three

Question 3

IEC Leads
A =
B =
C =

Answer 3

U
V
W

Question 4

Second step in Delta ID?

Answer 4

Find centre points (resistances)

Question 5

How many leads are on a six lead motor (lol)

Answer 5

six

Question 6

There is only three leads in a JB. How many leads are in this motor and why is there only three?

Answer 6

There is six leads but only three are brought out to the JB. The other three are connected for us by the manufacturer

Question 7

In a Wye-Delta starter, where are the overloads located?

Answer 7

In the phases

Question 8

What does a wye-delta motor require?

Answer 8

Mechanical interlock, three contactors and three overloads (one set)

Question 9

What kind of motor goes with a wye delta started?

Answer 9

delta

Question 10

What are the labels on a wye delta motor starter?

Answer 10

1,4
2,5
3,6

Question 11

What do we look for in a wye/delta started

Answer 11

Three groups of two leads
1,4
2,5
3,6

Question 12

Name a few examples of applications for part winding motors

Answer 12

fans, pumps, refrigerant compressors, machine tools

Question 13

What does a part winding motor require?

Answer 13

two contactors, two sets of overloads, no mechanical interlocks

Question 14

What are the applications of an across the line started?

Answer 14

almost any except for fragile things that will get broken by a large bump from starting torque

Question 15

Why would we use a part winding starter?

Answer 15

When we don’t need high starting torque

Question 16

What transition type is in a part winding motor?

Answer 16

closed

Question 17

What is the current reduction for a part winding motor starter?

Answer 17

60-65%

Question 18

What is the torque reduction for a part winding motor started

Answer 18

60-65% squared

Question 19

How many conductors go from the part winding starter to the motor?

Answer 19

six

Question 20

Do all conductors in a part winding starter carry full current?

Answer 20

no

Question 21

How many leads are in a part winding motor starter?

Answer 21

six

Question 22

What are the labels in a part winding motor?

Answer 22

T1, T2, T3, T7, T8, T9

Question 23

How many groups of three are there in a part winding motor starter?

Answer 23

two groups of three

Question 24

What is the most common winding method in a part winding motor?

Answer 24

Wye

Question 25

What are the two types of motor starters?

Answer 25

across-the-line, reduced voltage

Question 26

What is the typical inrush current when using an across the line starter?

Answer 26

500-600%

Question 27

What is the typical starting torque when using an across the line starter?

Answer 27

150%

Question 28

Where are the motor leads connected in an across the line starter?

Answer 28

directly to the source

Question 29

A motor capable of a part winding start has ___

Answer 29

two or more sets of three phase windings

Question 30

In a part winding motor only ___ is energized at start

Answer 30

one coil

Question 31

What is the percentage of inrush current in a part winding start in comparison to an across the line start?

Answer 31

60 - 65%

Question 32

Why would we use a reduced voltage starter?

Answer 32

when the high inrush current could cause excessive volt drop

Question 33

What does a reduced voltage starter do?

Answer 33

reduces the inrush current

Question 34

Besides current, what do reduced voltage starters also do?

Answer 34

reduce starting torque

Question 35

Why may we want to reduce starting torque?

Answer 35

Some loads, such as fragile ones may be damaged by the bump from the starting torque

Question 36

What is the main timer in motor starters?

Answer 36

Time delay on energization

Question 37

What are the terminals we will see on a TDOE?

Answer 37

TO (Timed open) and TC (Timed closed)

Question 38

In an autotransformer RV start, starting current to the motor is proportionate to ____

Answer 38

starting voltage

Question 39

What is the transition type of a wye delta motor?

Answer 39

open but can also be closed

Question 40

What is the reduction in current at start of a wye delta motor?

Answer 40

1/3 of FVS

Question 41

What is the voltage reduction at start in a wye delta motor starter?

Answer 41

Root 3 of FVS

Question 42

What is the formula to size the overload of an autotransformer starter?

Answer 42

FLA x Service factor multiplier

Question 43

What are the main types of motor starters that we will need to know?

Answer 43

Across the line/full voltage, wye delta, part winding, autotransformer

Question 44

What is the motor current reduction in an autotransformer starter motor?

Answer 44

I motor = %tap x I FVS

Question 45

What is the line current reduction in an autotransformer starter?

Answer 45

I FVS x %Tap^2

Question 46

What is the only motor starter where the line current reduction will be different from the motor current reduction?

Answer 46

autotransformer

Question 47

What is a closed transition?

Answer 47

When there is always a path for current from start to finish

Question 48

What is the torque reduction in an autotransformer starter?

Answer 48

Torque FVS x % Tap^2

Question 49

In a closed transition, is there always a path for current to flow from start to run process?

Answer 49

yes

Question 50

What is an open transition?

Answer 50

When there is a break in the path for current to flow from start to run even if it is for a moment

Question 51

All autotransformers are ___ transition

Answer 51

closed

Question 52

In a wye delta starter, where are the overloads located?

Answer 52

in the phase