Maintenance And Repair If Rotating Electrical Machinery Flashcards
What’s not the main objectives of shipboard preventative maintenance?
Generators being synchronized out of phase
The accumulation of dirt, moisture, and oil in generator and motor ventilation ducts causes local or general overheating for what reason?
The resistance to the dissipation of heat is increased
If you need to find the detailed procedures for cleaning electrical machinery, you should refer to what chapter of the NSTM?
300
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?
A suction blower placed at the opening opposite the air jet
What is not a cleaning solvent you should use when cleaning electrical equipment?
Alcohol
What type of bearing is designed to support loads resulting from forces that are applied perpendicular to the shaft?
Radial
In motor construction, what factor determines whether a thrust or radial bearing is installed?
Whether the motor is mounted vertically or horizontally
In operating machinery, you should suspect malfunctioning ball bearings of which of the following symptoms occur?
A high temperature
You are starting a motor. You can expect serious bearing problems if high temperatures are reached within what specified amount of operating time?
10-15 minutes
When grease cups for a motor aren’t used to grease bearings, where should they be kept?
In the custody of the responsible maintenance personnel
Of the following motors, which one can you grease without disassembling the bearing housing
A fire pump motor with an accessible drain hole
In the absence of other instructions, at what specified level should you maintain the oil in an oil lubricated, ball bearing motor housing?
Almost level with the bearing inner ring at the lowest point
To prevent damage to a bearing that you are pulling, you should place the bearing puller on the shaft and what other assembly?
The inner race
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?
To prevent damaging the shaft
When bearings are replaced on a shaft, the pressure should be applied to which of the following locations?
The bearing inner race
You are using the infrared method for mounting a motor bearing. The bearing temperature should NOT exceed which of the following temperatures?
203 degrees F + or - 10
Because of grease deterioration or contamination, which of the following methods of mounting bearings is undesirable?
The infrared method
Which of the following types of bearings are used on large propulsion generators and motors?
Journal
The sleeve bearings of a motor overheat. As a watch-stander, what action should you take?
Secure the load and let the motor run until the bearing cools
What type of bearing is designed to support loads resulting from forces that are applied perpendicular to the shaft?
Radial bearings
What bearing is used when the load is completely axial?
Thrust bearing
What type of bearing is used in an application where there are radial and thrust loads?
Angular contact bearing
What bearing types are examples of anti friction bearings?
Angular contact bearing
Radial bearing
Thrust bearing
What factors determine the grade of brush uses in a motor or generator?
The time in service
The size of the motor or generator
The load and speed of the motor or generator
What method should you use to calculate brush pressure?
Divide the spring pressure by the brush contact area
When seating a brush, you should use sandpaper and what other equipment?
A brush seater
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?
The brush
In the direction of rotation
