Maintenance And Repair If Rotating Electrical Machinery

Question 1

What’s not the main objectives of shipboard preventative maintenance?

Answer 1

Generators being synchronized out of phase

Question 2

The accumulation of dirt, moisture, and oil in generator and motor ventilation ducts causes local or general overheating for what reason?

Answer 2

The resistance to the dissipation of heat is increased

Question 3

If you need to find the detailed procedures for cleaning electrical machinery, you should refer to what chapter of the NSTM?

Answer 3

300

Question 4

You are blowing dust from a 75-kw generator using compressed air. What means should you use to remove the dust- laden air from the generator?

Answer 4

A suction blower placed at the opening opposite the air jet

Question 5

What is not a cleaning solvent you should use when cleaning electrical equipment?

Answer 5

Alcohol

Question 6

What type of bearing is designed to support loads resulting from forces that are applied perpendicular to the shaft?

Answer 6

Radial

Question 7

In motor construction, what factor determines whether a thrust or radial bearing is installed?

Answer 7

Whether the motor is mounted vertically or horizontally

Question 8

In operating machinery, you should suspect malfunctioning ball bearings of which of the following symptoms occur?

Answer 8

A high temperature

Question 9

You are starting a motor. You can expect serious bearing problems if high temperatures are reached within what specified amount of operating time?

Answer 9

10-15 minutes

Question 10

When grease cups for a motor aren’t used to grease bearings, where should they be kept?

Answer 10

In the custody of the responsible maintenance personnel

Question 11

Of the following motors, which one can you grease without disassembling the bearing housing

Answer 11

A fire pump motor with an accessible drain hole

Question 12

In the absence of other instructions, at what specified level should you maintain the oil in an oil lubricated, ball bearing motor housing?

Answer 12

Almost level with the bearing inner ring at the lowest point

Question 13

To prevent damage to a bearing that you are pulling, you should place the bearing puller on the shaft and what other assembly?

Answer 13

The inner race

Question 14

When cutting a seized bearing from a shaft, you should be careful to cut only 3/4 of the way through to inner ring. What is the reason for this precaution?

Answer 14

To prevent damaging the shaft

Question 15

When bearings are replaced on a shaft, the pressure should be applied to which of the following locations?

Answer 15

The bearing inner race

Question 16

You are using the infrared method for mounting a motor bearing. The bearing temperature should NOT exceed which of the following temperatures?

Answer 16

203 degrees F + or - 10

Question 17

Because of grease deterioration or contamination, which of the following methods of mounting bearings is undesirable?

Answer 17

The infrared method

Question 18

Which of the following types of bearings are used on large propulsion generators and motors?

Answer 18

Journal

Question 19

The sleeve bearings of a motor overheat. As a watch-stander, what action should you take?

Answer 19

Secure the load and let the motor run until the bearing cools

Question 20

What type of bearing is designed to support loads resulting from forces that are applied perpendicular to the shaft?

Answer 20

Radial bearings

Question 21

What bearing is used when the load is completely axial?

Answer 21

Thrust bearing

Question 22

What type of bearing is used in an application where there are radial and thrust loads?

Answer 22

Angular contact bearing

Question 23

What bearing types are examples of anti friction bearings?

Answer 23

Angular contact bearing
Radial bearing
Thrust bearing

Question 24

What factors determine the grade of brush uses in a motor or generator?

Answer 24

The time in service
The size of the motor or generator
The load and speed of the motor or generator

Question 25

What method should you use to calculate brush pressure?

Answer 25

Divide the spring pressure by the brush contact area

Question 26

When seating a brush, you should use sandpaper and what other equipment?

Answer 26

A brush seater

Question 27

When seating a brush, you should place the sandpaper between the brush and the commutator with the rough side toward what component and pull in what direction?

Answer 27

The brush In the direction of rotation