Single-Phase Motors Overview

<p>Adjustable pulleys provide more flexibility for speed adjustments in specific applications. (D)</p> Signup and view all the answers

<p>Excessive tension can increase bearing and shaft wear, potentially shortening motor lifespan. (B)</p> Signup and view all the answers

<p>Lighter materials reduce rotational inertia, which improves motor efficiency. (B)</p> Signup and view all the answers

<p>The amount of electrical current available to the motor. (C)</p> Signup and view all the answers

<p>Adjusting the pulley can alter the speed ratio between the motor and driven equipment. (C)</p> Signup and view all the answers

<p>Low starting torque (C)</p> Signup and view all the answers

<p>The direction of rotation is changed (B)</p> Signup and view all the answers

<p>Air-cooled condensers (B)</p> Signup and view all the answers

<p>Operates with three phases 120 degrees out of phase (C)</p> Signup and view all the answers

<p>It reduces the motor's operational speed (B)</p> Signup and view all the answers

<p>Very efficient and suitable for high-torque applications (A)</p> Signup and view all the answers

<p>High starting torque is present (B)</p> Signup and view all the answers

<p>1 hp to thousands of horsepower (C)</p> Signup and view all the answers

<p>Causes belt slippage. (B)</p> Signup and view all the answers

<p>Causes increased vibration and noise. (A)</p> Signup and view all the answers

<p>Results in uneven wear. (B)</p> Signup and view all the answers

<p>Fine-tunes equipment speed. (B)</p> Signup and view all the answers

<p>Increased noise and slippage. (B)</p> Signup and view all the answers

<p>Proper selection and alignment of pulleys. (C)</p> Signup and view all the answers

<p>Increased maintenance costs. (C)</p> Signup and view all the answers

<p>Combination Misalignment. (B)</p> Signup and view all the answers

<p>Simpler design (A)</p> Signup and view all the answers

<p>Low-torque fan sections (C)</p> Signup and view all the answers

<p>The gradual increase in speed (C)</p> Signup and view all the answers

<p>To improve motor efficiency during operation (A)</p> Signup and view all the answers

<p>It will overheat when operating at full load (B)</p> Signup and view all the answers

<p>Improved airflow control (C)</p> Signup and view all the answers

<p>825 rpm (C)</p> Signup and view all the answers

<p>To maintain proper heat rise (B)</p> Signup and view all the answers

<p>To prevent slippage or excessive wear (C)</p> Signup and view all the answers

<p>Run capacitor (C)</p> Signup and view all the answers

<p>Voltage is steady and accurately recorded (B)</p> Signup and view all the answers

<p>Capacitance(MFD) = Start Winding Amps x 2652 / Voltage (D)</p> Signup and view all the answers

<p>The capacitor should be replaced (B)</p> Signup and view all the answers

<p>Open Load (D)</p> Signup and view all the answers

<p>Ammeter (A)</p> Signup and view all the answers

<p>To provide a higher starting torque by creating a phase shift. (A)</p> Signup and view all the answers

<p>Because the capacitor is no longer needed for motor operation at that point. (D)</p> Signup and view all the answers

<p>CSCR motors use a second capacitor for running, while capacitor-start motors only use one for starting. (B)</p> Signup and view all the answers

<p>CSCR motors provide improved efficiency during both starting and running. (C)</p> Signup and view all the answers

<p>Compressors, pumps, fans, and air conditioning units. (A)</p> Signup and view all the answers

<p>The motor will start, but eventually it will overheat and potentially be damaged. (D)</p> Signup and view all the answers

<p>The capacitor in a capacitor-start motor helps create a higher starting torque compared to a split-phase motor. (A)</p> Signup and view all the answers

<p>Internal overload is open. (C)</p> Signup and view all the answers

<p>Back EMF from the motor. (A)</p> Signup and view all the answers

<p>Back EMF from the motor. (C)</p> Signup and view all the answers

<p>187.2V - 253V (A)</p> Signup and view all the answers

The capacitor creates a phase shift, helping the motor overcome initial resistance and start efficiently. It's removed once the motor reaches running speed.

The capacitor is disconnected from the circuit once the motor reaches operating speed. This is because it's not needed for continuous operation and could even damage the capacitor.

A capacitor-start motor produces much higher starting torque compared to a basic split-phase motor, enabling it to handle heavier loads.

Like the split-phase motor, its design is relatively simple with fewer components compared to more complex motors.

A motor that utilizes both start and run capacitors, providing higher starting torque and efficient continuous operation.

The start capacitor has a higher microfarad rating than the run capacitor, increasing starting torque.

The start capacitor is removed after the motor reaches speed, while the run capacitor remains in the circuit to aid continuous operation.

CSCR motors are highly efficient for both startup and continuous operation due to the presence of both start and run capacitors.

A type of AC motor that uses shading coils on each pole to create an induced current and a rotating magnetic field.

Coils placed on each pole of a shaded-pole motor that help start the motor. They create an induced current which generates a rotating magnetic field.

The ability of a motor to overcome inertia and begin to rotate. Shaded-pole motors have lower starting torque because of their design.

Refers to how the motor converts electrical energy into mechanical energy. Efficiency is measured by the ratio of output power to input power. Shaded-pole motors are less efficient than some other motor types.

A type of AC motor that uses three single-phase power supplies, each with 2 or 4 poles, to create a rotating magnetic field.

The speed at which the magnetic field in a motor rotates. In a three-phase motor, the synchronous speed is determined by the number of poles and the frequency of the power supply.

The difference between the synchronous speed and the actual speed of the motor. It's caused by the load placed on the motor, and is typically lower for higher loads.

A motor rated for use with three-phase power. These motors are known for their efficiency, high starting torque, and ability to handle large loads.

A type of AC motor that utilizes a single capacitor for both starting and running the motor. It's considered the simplest type of split-phase motor due to the lack of a separate start winding and a start switch.

A type of AC motor that uses two windings: a start winding and a run winding. During motor start-up, a capacitor connected to the start winding creates a phase shift, causing the motor to start rotating. This capacitor is disconnected once the motor reaches a certain speed.

A capacitor connected to the start winding in a split-phase motor to create a phase shift for starting torque. It's only energized during the starting phase of the motor, typically disconnected by a centrifugal switch once the motor reaches a certain speed.

A capacitor connected to the run winding in a split-phase motor. Responsible for maintaining the motor efficiency and performance while it's operating at a steady speed.

A special type of PSC motor with multiple wiring connections. The speed of the motor can be adjusted by altering the resistance in the circuit. Common in HVAC systems for controlling fan speeds.

The number of magnetic poles in a motor determines the synchronous speed of the motor. A motor with more poles will rotate slower, while a motor with fewer poles will rotate faster. The actual speed of the motor is slightly lower due to slip.

The process of starting a motor gradually without abrupt acceleration. This reduces noise and wear and tear, especially beneficial for fan applications close to the return air intake.

Measuring resistance between the motor's start and run terminals provides the highest resistance reading.

If you know the resistance between start and common, and run and common, you can calculate the start-to-run resistance by adding those two values.

All three windings in a three-phase motor are designed to have equal resistance.

Motor pulley size affects the driven equipment speed. A larger pulley increases speed, while a smaller pulley decreases it.

A larger pulley can increase motor load and current draw, potentially shortening lifespan if the motor is undersized.

A smaller pulley reduces motor load and current draw, but if the speed is too low, it can affect equipment performance.

Pulley diameter directly influences belt tension, which must be matched to the desired speed ratio between the motor and equipment.

Proper pulley adjustment ensures optimal motor operation, efficiency, and reliability.

The belt is too tight, causing excessive strain on the motor, potentially leading to overheating or premature failure.

The belt is too loose, causing slippage and reducing torque transfer. This leads to decreased system efficiency and increased wear on both the belt and pulley.

Adjusting pulley position along the motor shaft can improve belt alignment, reducing wear and ensuring smooth power transmission.

Variable pulley allows for fine-tuning motor speed without replacing components. However, incorrect adjustments can cause speed mismatches, inefficiency, or motor overload.

The motor and driven pulley are aligned parallel with their grooves aligned. This prevents belt wear, excess vibration, and stress on motor bearings.

Pulleys are not parallel, causing uneven belt wear, vibration, and inefficient power transfer.

Pulley grooves aren't aligned, causing belt tracking issues, slippage, and increased noise.

A mix of angular and offset misalignment, leading to severe mechanical problems like increased wear and vibration.

A tool used to measure the electrical current flowing through a specific circuit, providing insights into the motor's power consumption.

A measurement of a capacitor's ability to store electrical charge, often expressed in microfarads (µF).

The maximum deviation allowed for a measured value from its nominal rating, expressed as a percentage.

A test that involves measuring the current flowing through a motor's start winding and the voltage across the start capacitor, then calculating the capacitance.

A common failure mode in electric motors where the winding insulation breaks down due to excessive heat, causing shorts and decreased performance.

A common failure in electric motors where the bearings supporting the motor shaft wear out, leading to increased friction, noise and potential damage.