Podcast
Questions and Answers
What is the purpose of recording name plate information during motor replacement?
What is the purpose of recording name plate information during motor replacement?
Which of the following is NOT included in the important name plate data for motor replacement?
Which of the following is NOT included in the important name plate data for motor replacement?
What type of oil is recommended for sleeve bearings?
What type of oil is recommended for sleeve bearings?
What maintenance practice should be avoided to prevent damage to a motor?
What maintenance practice should be avoided to prevent damage to a motor?
Signup and view all the answers
How often should hand-packed bearings be disassembled and repacked with grease?
How often should hand-packed bearings be disassembled and repacked with grease?
Signup and view all the answers
What must be done before servicing an electric motor?
What must be done before servicing an electric motor?
Signup and view all the answers
Which maintenance practice is most necessary for electric motors?
Which maintenance practice is most necessary for electric motors?
Signup and view all the answers
What should not be mixed in motor bearings to avoid damage?
What should not be mixed in motor bearings to avoid damage?
Signup and view all the answers
What is a primary advantage of using a totally enclosed motor?
What is a primary advantage of using a totally enclosed motor?
Signup and view all the answers
Which type of drive utilizes a piece of rubber or plastic for connection?
Which type of drive utilizes a piece of rubber or plastic for connection?
Signup and view all the answers
What is the purpose of a capacitor in an electrical motor?
What is the purpose of a capacitor in an electrical motor?
Signup and view all the answers
Which type of motor is ideal for variable speed control?
Which type of motor is ideal for variable speed control?
Signup and view all the answers
What type of bearing is suitable for high shaft load capacity?
What type of bearing is suitable for high shaft load capacity?
Signup and view all the answers
What is the equivalent of 1 Horsepower (HP) in watts?
What is the equivalent of 1 Horsepower (HP) in watts?
Signup and view all the answers
What is the function of starting torque in a motor?
What is the function of starting torque in a motor?
Signup and view all the answers
Which motor control type provides protection against overheating?
Which motor control type provides protection against overheating?
Signup and view all the answers
What type of switch does NOT typically offer overload protection?
What type of switch does NOT typically offer overload protection?
Signup and view all the answers
What electrical measurement is represented by Hertz?
What electrical measurement is represented by Hertz?
Signup and view all the answers
Which component absorbs vibration and noise in a motor's base?
Which component absorbs vibration and noise in a motor's base?
Signup and view all the answers
Which type of pulley design reduces slippage and belt turnover?
Which type of pulley design reduces slippage and belt turnover?
Signup and view all the answers
What do thermal overload protections provide?
What do thermal overload protections provide?
Signup and view all the answers
What is the primary function of resistance temperature detectors (RTDs) in electric motors?
What is the primary function of resistance temperature detectors (RTDs) in electric motors?
Signup and view all the answers
What does the 'Duty' rating on a motor’s nameplate indicate?
What does the 'Duty' rating on a motor’s nameplate indicate?
Signup and view all the answers
What is the potential consequence of neglecting to clean motor surfaces and ventilation openings?
What is the potential consequence of neglecting to clean motor surfaces and ventilation openings?
Signup and view all the answers
Why is it crucial to consult the operator's manual before lubricating an electric motor?
Why is it crucial to consult the operator's manual before lubricating an electric motor?
Signup and view all the answers
What could happen if petroleum-based and silicone-based greases are mixed in motor bearings?
What could happen if petroleum-based and silicone-based greases are mixed in motor bearings?
Signup and view all the answers
For the common sleeve bearings, what type of oil is typically recommended?
For the common sleeve bearings, what type of oil is typically recommended?
Signup and view all the answers
In regard to hand-packed ball bearings, what maintenance should be performed on them?
In regard to hand-packed ball bearings, what maintenance should be performed on them?
Signup and view all the answers
In the replacement process, what is the primary benefit of accurately recording nameplate information?
In the replacement process, what is the primary benefit of accurately recording nameplate information?
Signup and view all the answers
Which motor enclosure design allows outside air to directly cool the windings?
Which motor enclosure design allows outside air to directly cool the windings?
Signup and view all the answers
In what type of environment would a totally enclosed motor be MOST appropriate?
In what type of environment would a totally enclosed motor be MOST appropriate?
Signup and view all the answers
Which type of motor mounting is specifically designed to reduce vibration and noise?
Which type of motor mounting is specifically designed to reduce vibration and noise?
Signup and view all the answers
Which of the following is a crucial consideration when selecting a motor shaft type?
Which of the following is a crucial consideration when selecting a motor shaft type?
Signup and view all the answers
What is a critical factor when mounting a sleeve bearing motor?
What is a critical factor when mounting a sleeve bearing motor?
Signup and view all the answers
Where are ball bearings MOST commonly used in motors?
Where are ball bearings MOST commonly used in motors?
Signup and view all the answers
What type of coupling utilizes a rubber or plastic hose as the driving connection?
What type of coupling utilizes a rubber or plastic hose as the driving connection?
Signup and view all the answers
For what purpose is a flexible shaft primarily used?
For what purpose is a flexible shaft primarily used?
Signup and view all the answers
Which type of drive is commonly seen on farms?
Which type of drive is commonly seen on farms?
Signup and view all the answers
Which pulley type is known for reducing slippage and preventing belt turnover?
Which pulley type is known for reducing slippage and preventing belt turnover?
Signup and view all the answers
What is the standard voltage frequency in North America?
What is the standard voltage frequency in North America?
Signup and view all the answers
What does the measurement of amperage indicate within an electrical motor?
What does the measurement of amperage indicate within an electrical motor?
Signup and view all the answers
What does the term 'breakdown torque' refer to in a motor's performance?
What does the term 'breakdown torque' refer to in a motor's performance?
Signup and view all the answers
What is the purpose of motor controls that limit inrush?
What is the purpose of motor controls that limit inrush?
Signup and view all the answers
Which type of thermal overload protection requires an external button to restore power after a trip?
Which type of thermal overload protection requires an external button to restore power after a trip?
Signup and view all the answers
Study Notes
Electrical Motor Selection & Maintenance
- Objectives: Identify components for motor selection, explore maintenance techniques, and identify motor replacement information.
Major Motor Types
-
Alternating Current (AC) motors:
- Single-phase motors
- Polyphase (three-phase) motors (require three-phase service).
-
Direct Current (DC) motors:
- Ideal for variable speed control.
- Used when AC is unavailable.
End Bells & Enclosures
-
Open enclosure:
- Motor casting and ends are vented
- Outside air cools the windings.
- Less expensive.
-
Totally enclosed:
- Motor casting and ends are enclosed.
- Prevents outside air (wet, flammable, corrosive, dirty) from entering the motor.
External Features
- Open enclosure
- Totally enclosed
External Features Mounting
- Solid, rigid base: Motor mount is part of the motor casting.
-
Resilient base:
- Mount is separate from the motor.
- Resilient rings absorb vibration and noise.
- Conductor attached to complete grounding.
Internal Features Shaft
- Shaft is a round rod protruding through the motor center.
- Responsible for power output.
- Keyed shaft and threaded shaft types must be considered.
Internal Features Sleeve Bearing
- Brass, bronze, or tin-lined cylinder.
- Mounted parallel to the floor.
- End shield may need rotating to prevent oil spill issues.
- Used where low noise is important.
Internal Features Ball Bearing
- Round steel balls in a special cage surround the shaft.
- Can be mounted in any position.
- Used when high shaft load capacity is needed.
Mechanical Considerations Drives
-
Types of direct drives:
- Flexible hose coupling drive: Plastic or rubber hose as the drive.
- Flange coupling: Two metal discs and a flexible middle disc; “flange” attaches to motor, other to equipment.
- Cushion-flange coupling: Tire-shaped cushion between flanges.
- Flexible shaft: Used for operating at various angles (e.g., grinders, buffers).
- Gear drives & Chain & sprocket drives
Mechanical Considerations Pulley & Belt Drive
- Often used in farming.
- Larger pulleys offer reduced slippage.
- Standard V pulley
- V-step pulley
- Adjustable V pulley
Mechanical Considerations Types of Pulleys
-
V-belt:
- Motor mounted closer to machine.
- Belt stays on better.
- Webbed multi V-belt: Two or more V-belts webbed together; eliminates slippage, belt turnover.
- Flat belt: Requires flat pulley on motor and machine.
- V-flat: One or more V-belts, one V-pulley and one flat pulley.
Electrical Considerations Voltage
-
Common 60Hz voltages:
- Single-phase motors: 115V, 230V, 115/230V
- Three-phase motors: 230V, 460V, 230/460V
Electrical Considerations Current (Amps)
- Measures current flow.
- Capacitor stores electrical energy and blocks current flow.
- Capacitor starts motor and assists primary windings' speed attainment.
Electrical Considerations Hertz Frequency
- Hertz measures electrical frequency (cycles per second).
- North America: 60Hz
- All other countries: 50Hz
Electrical Considerations Horsepower (HP)
- Measures work rate.
- 746 watts = 1 HP (at 100% capacity).
- Watts x % capacity = 746 or 1 HP.
Electrical Considerations Torque
- Force applied to a shaft.
- Usually expressed in inch-pounds.
- Torque = distance × weight.
- "Twisted force".
-
Torque Types:
- Starting (locked rotor) torque: Force from standstill to acceleration.
- Full-load torque: Force while running at rated horsepower and full-load speed.
- Breakdown (pull-out) torque: Maximum torque a motor can produce without speed drop due to load increase.
- Pull-up torque: Minimum torque when increasing from zero RPM.
Motor Controls
- Manual, semi-automatic, and automatic controls protect motors from overheating.
- Functions: Limiting inrush, reversing the motor, controlling speed, and acting as a brake.
- Types of switches: Pushbutton, toggle, snap action (with/without overload protection).
Overload Protection Thermal Protection (Overload)
- Built-in overload protection: Automatic reset (power restored once cooled). Unexpected starts can be hazardous. Manual reset (external button; for applications like saws and conveyors where unexpected starts are hazardous).
- Resistance temperature detectors(RTD): Resistors mounted onto machines used with heat detection instruments.
Replacement Factors
- Nameplate data
- Motor type
- Mechanical construction
- Electrical and performance characteristics.
Replacement Name Plate Data
- Most important step in the process.
- Record name plate information (saves time, avoids confusion, prevents misapplications)
-
Name Plate Data to Record:
- Type (AC or DC)
- Phase (single or three)
- Horsepower (HP)
- Rotations per minute (RPM)
- Duty (e.g., 15, 20, continuous)
- Code (current required for start)
Maintenance
- Properly selected and installed motors operate for many years with little maintenance.
- Disconnect power before servicing.
- Clean motor surfaces and ventilation openings (dust and lint) to prevent overheating and failure.
Maintenance Lubrication
- Essential maintenance type.
- Consult operator manuals.
- Excessive/frequent lubrication damages motors.
- Adhere to motor-supplied instructions.
- Avoid mixing petroleum and silicone grease in motor bearings.
Maintenance Bearings
- Sleeve bearings: Use SAE 20 non-detergent or electrical motor oil. Avoid over-oiling; wipe off excess.
- Ball bearings: Hand-packed bearings need disassembly and greasing every 2-5 years.
- Special fittings bearings require bottom plug removal for greasing.
Acknowledgements
- Credits for multiple sources of information used in creating these notes. (Note: Specific acknowledgments are included in the original OCR.)
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on selecting and maintaining electrical motors. This quiz covers various motor types, including AC and DC motors, and dives into essential features such as enclosure types and mounting options. Gain a better understanding of motor applications and maintenance techniques.
