Equipment Maintenance Flashcards
Why must unqualified or inexperienced people be extremely careful when attempting to troubleshoot or repair electrical equipment?
Unqualified or inexperienced person must be extremely careful when attempting to troubleshoot or repair electrical equipment because they can be seriously injured and damage costly equipment if a mistake is made
page 153
What could happen when Machinery is not shut off locked out and tagged properly?
When machinery is not shut off locked out and tag properly the following accidents could occur:
Maintenance operator could be clean a pump and have it start that’s losing an arm hand or finger.
Electrical motors or controls not properly grounded could lead to possible severe shot paralysis or death.
Improper circuit such as wrong connections bypassed safety devices wrong fuses or improper wiring can cause fires or injuries due to incorrect operation of Machinery.
Page 153
How can you determine the proper voltage and allowable current in amps for a piece of equipment?
The proper voltage and allowable current in amps for a piece of equipment can be determined by reading the name plate information or the instruction manual for the equipment.
Page 154
What are two types of voltage?
Special types of voltage are direct current DC and alternating current AC
Page 154
Amperage is a measurement of what?
Amperage is a measurement of current or electron flow and is an indication of work being done or how hard the electricity is working page 155
How can you determine if there is voltage in a current?
You test for voltage by using a multimeter. Page 156
What are some of the uses of a multimeter?
A multimeter can be used to test for voltage open circuit blown fuses single phasing of motors and grounds. Page 157
What precaution should be taken before attempting to change fuses?
Before attempting to change fuses turn off power and check both power lines for voltage. Use a fuse puller. Page 157
How do you test for voltage with a multimeter when the voltage is unknown?
If the voltage is unknown and the multimeter has different scales that are manually set always start with the highest voltage range and work down. Otherwise the multimeter could be damaged. Page 158
What could be the cause of an amp reading different from the nameplate rating?
Amp readings different from the nameplate rating could be caused by low voltage, bad bearings, poor circulation, plugging or excessive load. Page 158
How often should Motors and wines be megged?
Motors and wiring should be megged at least once a year. And twice a year. If possible. Page 159
An ohmmeter is used to check the ohms of resistance in what control circuit components?
An ohmmeter is used to test the control circuit components such as: coils. Fuses. Relays. Resistors. And switches. Page 159
What is the most common pump driver used in lift stations?
The most common pump driver used in lift stations is the AC induction motor.
Page 160
Basic lift station maintenance procedures performed at least annually will help minimize what type of lift station failures
Types of lift station failures that can occur due to lack of proper maintenance include:
- Current and balances or imbalances which ultimately result in motor failure.
- Lose contacts or terminals in control and power circuits causing High Resistance contacts.
- Overheating resulting in arcing fire and electrical system damage.
- Dirty enclosures and components which allows a conducted path to build up between incoming phases causing phase to phase shorts.
- Corrosion that causes high resistance contacts with you. Page 160
What should be done when a fuse or circuit-breaker blows or trips?
If a fuse or circuit-breaker blows or trips the potential source of the problem should be investigated identify and correct it.
Page 162
What are fuses used to protect?
Fuses are used to protect operators main circuits Branch circuits and Equipment such as heaters and motors from excessive current. Page 162
Why must fuses never be bypassed or jumped?
A fuse must never be bypassed or jumped because the fuse is the only protection the circuit has. Without it serious damage to equipment and possible injury to operators can occur. Page 162
What are the two types of overcurrent devices that should be installed to protect the main control panel and wiring from damage due to excessive voltage or amperage?
Fuses and circuit breakers are overcurrent devices that should be installed to protect the main control panel and wiring from damage due to excessive voltage or amperage. Page 163
What types of annual maintenance should be performed with regard to fuses?
Annual maintenance that should be performed with regard to fuses include:
Inspect all bolted connections at all fuse clips of fuse holder for signs of looseness.
Check connections for any evidence of corrosion from washer or atmosphere air pollution.
Tighten connections.
Check fuse for obvious overheating.
Inspect insulation of the conductors coming into the fuses on the line side and out of the fuses on the load side for evidence of discoloration or bubbling which would indicate overheating of the conductors. Page 163
How does a circuit breaker work to provide protection from excessive current for equipment and conductors?
Circuit breakers provide protection from excessive current for equipment and conductors without the inconvenience of changing fuses.
Circuit breakers trip (open the circuit) when the circuit flow is excessive.
In a magnetic circuit breaker the current is sensed by a coil that forms and electromagnet
When the current is excessive the electromagnet activates a small armature that pulls a trip mechanism thus opening the circuit breaker.
In the thermal type of circuit breaker the current heat a bimetallic strip when heated sufficiently the strip Bends enough to allow the trip mechanism to operate. Page 163
Motor and supervisory control systems are composed of what types of auxiliary electrical equipment?
The motor and supervisory control systems are composed of the auxiliary electrical equipment such as relays Transformers light panels pump control logic alarms and other electrical equipment typically found in a lift station electrical system. Page 166
What are the three basic factors that contribute to the reliable operation of electrical systems found in lift stations?
The three basic factors that contribute to the reliable operation of electrical systems found in a lift stations include:
*And adequate preventive maintenance program must be implemented and maintained. *A knowledge of the system by the collection system operator even though the operator does not perform the actual maintenance.
Adherance to three principles keep it clean keep it dry keep it tight. Page 167
What are the two types of indication motor construction typical encounter when dealing with AC induction Motors?
The two types of induction motor constructions that are typically encountered when dealing with AC induction Motors are:
*Squirrel cage induction motor *Wound cage induction motor. Page 167
List the five most common causes of electrical motor failure.
The five most common causes of electric motor failure are: Overload (thermal) Contaminants. Single phasing. Bearing failures. Old age. Page 170
List the three components of a insulation temperature rating.
The three components of an insulation temperature rating consist of: Ambient operating temperature. Temperature rise. Hotspot allowance. Page 170-171
How are motor starters controlled?
Motor starters can be either manually or automatically controlled. Page 175
When are magnetic starters used?
Magnetic starters are usually used to start pumps compressors blowers and anything were automatic or remote control is desired. Page 175
What two types of overload protection devices are used on magnetic starters?
The two types of overload protection devices used on magnetic starters are:
A bimetallic strip that is precisely calibrated to open under higher temperature conditions to de-energize the coil.
A small solder pot within the coil that melts because of the Heat and will de-energizer the system. Page 176
How can the direction of rotation of a 3-phase motor be changed?
The direction of rotation of a 3-phase motor can be changed by changing any two of the power leads. Page 180
What is the key to effective troubleshooting?
The key to effective troubleshooting is practical step-by-step procedures combined with a common sense approach page 183
What are some of the steps that should be taken when troubleshooting magnetic starters?
When troubleshooting magnetic starters:
Gather preliminary information.
Inspect.
Contacts
mechanical Parts
magnetic parts
page 186-187What kind of information should be recorded regarding the electrical equipment?
Information that should be recorded regarding electrical equipment includes every; Change.
Repair.
Test.
Page 188
What are some uses of pumps?
Pumps are used to move waste water in collection systems with a gravity system is not feasible or too costly. In the collection system there are used in lift stations were it is necessary to lift the water from a low elevation to a higher elevation. Pumps also are used in High Velocity cleaners for cleaning collection systems. They are used to dewater trenches or excavations while installing pipelines or repairing them. Automobile have oil pumps and water pumps while backhoes have hydraulic pumps. Page 192
Why is it important to know how a pump is built?
If we know how pump is built it is easier to understand how to operate and maintain a pump.
What are the main points to keep in mind regarding the lubrication of a pump
Keep the right amount of right lubricant in bearings at all times. Follow your pump manufacturers lubrication instructions to the letter. The main points to keep in mind are:
Although too much oil will not harm sleeve bearings too much grease and anti-friction type bearings (ball or roller) will promote friction and heat
The main job of grease in anti-friction bearings is to protect steel elements against corrosion not friction.
Operating conditions vary so widely that no one will rule as to frequency of changing lubricant will fit all pumps.
So play it safe if anything change lubricant before it is too warm or too dirty. Page 194 195
Why is it so important to see that the pump and the motor flanges are parallel vertically and axially and that they are kept that way?
See that the pump and motor flanges are parallel vertically and axially and that they are kept that way.
If shafts are eccentric or meeting at an angle every Revolution throws tremendous extra load and bearings are both pump and motor.
Flexible couplings will not correct this condition if excessive.
Checking alignment should be a regular procedure and pump maintenance.
Foundations can settle on unevenly piping can change pump positions both can loosen. Misalignment is a major cause of pump and coupling wear. Page 195
Why must horizontal suction lift piping always slope upward toward the pump?
Horizontal suction lift piping always slopes upward toward the pump. The upsloping prevents air pocketing in the top of the pipe we’re trapped air might be drawn into the pipe and cause loss of suction. Page 195
