Richard Class

Question 1

LINE VA formula

3 phase

Answer 1

E line x I line x 1.73

Question 2

Line WATTS formula

3 phase

Answer 2

E line x I line x 1.73 x power factor

Question 3

Power factor formula (2)

Answer 3

Cos angle or watts/va

Question 4

Other names for VA and Watts

Answer 4

Power theoretical and power actual

Question 5

Maximum voltage imbalance BETWEEN PHASES

Answer 5

2%

Question 6

Why are brass bars skewed on squirrel rotor

Answer 6

To provide more uniform motor torque (less jitters)

Question 7

Maximum POWER SUPPLY. Variations

Answer 7

+/- 10%

Question 8

NEMA design with most efficiency

Answer 8

NEMA A

Question 9

TQ question

How to increase starting torque on VFD

Answer 9

Reduce frequency output….. but not really

Question 10

NEMA A

Current / starting torque

Answer 10

600%/ 150%

Question 11

NEMA B

Starting current / torque

Answer 11

500%/ 150%

Question 12

NEMA C

Starting current / torque

Answer 12

500%/ 225%

Question 13

NEMA D

Starting current / torque

Answer 13

400%/ 275%

HIGH INERTIA LOADS (punch press)

Question 14

Best method of joining conductors

Answer 14

Solder

Question 15

What is a class 2 circuit

Answer 15

Less than 150V at 100 VA

Question 16

The larger the capacitor the _____ it will charge and discharge

Answer 16

Slower

Question 17

Capacitors oppose the change in….

Answer 17

Voltage

Question 18

1 TC is equal to…

Answer 18

63.2% of difference
(0->100v = 63.2v)
(100->200v = 163.2v)

Question 19

E leads I. I leads E

By how many degrees

Answer 19

90

Question 20

Electrolytic start capacitors designed for maximum number of starts…

Answer 20

20 per hour at 3 second starts

Question 21

Current carrying conductors are affected by 4 factors

Answer 21

MALT
Material
Area (cross sectional)
Length
Temperature

Question 22

Analog Megaohmmeter (merger) when turned off reads…

Answer 22

Near infinite or over scale

Question 23

L and M terminals on OFC

Answer 23

Overload trip

Question 24

Timer settings on OFC heater

Answer 24

30/60/90 second time out

Question 25

OFC pressure connections

Answer 25

Crank case pressure
—————-
Oil pump discharge

Question 26

Purpose of resistor in OFC cct

Answer 26

Voltage drop resistor (120v)

Question 27

1mA will cause

Answer 27

Fuck all, no harm

Question 28

Damper actuator is fully open at ____ V

Answer 28

24, no voltage to actuator means fully closed

Question 29

Most common substation transformer configuration

Answer 29

4 wire Y

Question 30

VFD NETURAL carries _____ current

Answer 30

Excessive

Question 31

Counter torque causes motor to…

Answer 31

Slow down

Question 32

VFD construction

Answer 32

Thinner steel laminations in rotor
Better winding insulation
Shaft bonding rings
Insulated bearings

Question 33

TQ question

3 main parts of VFD

Answer 33

Rectifier
dc link filter
Inverter

Question 34

Voltage imbalance formula

Answer 34

Greatest difference
—————————
Average voltage

Question 35

Arc flash temp

Answer 35

35000F

Question 36

How many contactors does a wye delta starter need

Answer 36

3

Question 37

Reduced voltage starting method that is adjustable the entire way

Answer 37

Solid state

Question 38

Multi winding motors, can you apply more voltage across each winding?

Answer 38

No. Each winding is rated for a maximum set voltage
Eg.
240 volts is 2 windings in series (120 per winding)
120 is 2 windings in parallel (120 per winding still)

Part winding is reduced voltage on one winding (120 per winding)