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Exam Flashcards

1
Q

List 3 Disadvantages of the Torque Synchro Chain

A
  1. Stuck Position Error: If any one of the receiver rotors sticks, it modifies the transmitted signal, causing other receivers to align incorrectly.
  2. Limited Torque Output: The torque output is limited, meaning it can’t drive very heavy loads effectively.
  3. Overall Accuracy: The accuracy of the torque synchro chain is limited to about 1 degree due to the small change in flux which cannot overcome the inertia of the receiver rotor for small movements.
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2
Q

Explain the operation of a Coarse/Fine Control chain using an example application

A

A coarse/fine control chain uses two separate control chains for improved accuracy:

  1. Coarse Chain: Manages large misalignments for quick, rough positioning.
  2. Fine Chain: Takes over near alignment for precise adjustments.

Example: In a naval gun system, the coarse chain moves the gun towards the target, and the fine chain fine-tunes the aim as it gets closer.

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3
Q

Explain how 180 degrees misalignment is avoided in EVEN systems

A
  1. Biasing: Add part of the reference voltage to the coarse CT output to shift the error voltage curve.
  2. Racking: Rotate the synchro body while holding the rotor to adjust the error voltage
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4
Q

State and briefly explain what technique is used to remedy the problem associated with EVEN gear ratio coarse/fine chains?

A

Stick-Off Bias.

  1. Biasing: Adding a portion of the reference voltage to the coarse control transformer’s output shifts the error voltage curve.
  2. Racking: Rotating the synchro body while keeping the rotor stationary adjusts the error voltage curve sideways.

These adjustments ensure the stable zero positions of the coarse and fine chains align, preventing 180-degree misalignment.

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5
Q

State the relationship between input, output and error for a closed loop system.

A

CHECK

θe = θi - θo

where:

•	θi is the input (desired state),
•	θo is the output (actual state),
•	θe is the error (difference between the desired and actual state).
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6
Q

What is the gain or sensitivity of a system in terms of θout and θIN.

A

Gain = θout / θIN

where:
- θout is the output,
- θIN is the input.

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7
Q

What are the three components of friction?

A

The four components of friction are:

  1. Static Friction: The resistance to the start of motion between two surfaces in contact.
  2. Kinetic (Dynamic) Friction: The resistance between two surfaces in relative motion.
  3. Rolling Resistance: The resistance encountered when an object rolls over a surface, caused by deformations in the object or surface.
  4. Viscous (Fluid) Friction: The resistance experienced by an object moving through a fluid (liquid or gas).
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8
Q

Name 3 problems associated with power drives and explain their symptoms?

A

Three problems associated with power drives and their symptoms are:

  1. Backlash: Causes oscillation and loss of motion between input and output when direction changes.
  2. Resilience (Yield): Leads to overshooting and oscillation due to torsional twist in drive shafts under torque.
  3. Friction: Causes sluggish movement, increased power requirement, and steady-state errors due to continuous resistance.
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9
Q

How to overcome the 3 problems associated with power drives?

A

To overcome the three problems associated with power drives:

  1. Backlash: Use high-quality, well-designed gears and use of hydraulic shrink fits.
  2. Resilience (Yield): Implement divided reset systems.
  3. Friction: Employ good design and maintenance.
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10
Q

What is the effect of crossing stator leads S1-S3 in a synchro chain in terms of rotation and phase?

A

The receiver stator flux rotates from a correct datum in the opposite direction to the input

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11
Q

What is the effect of stepping stator leads in a synchro chain in terms of rotation and phase?

A

Receiver stator flux steps 120 degrees out of alignment but rotates in the same direction as the input

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12
Q

What is the effect of crossing rotor leads in a synchro chain in terms of rotation and phase?

A

Receiver status flux lines up 180 degrees out of alignment.

Stator flux is completely reversed

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13
Q

Wiring faults

A
  1. Crossing Stator Leads:
    • Stator leads S1 and S3 (or S2 and S1, S3) are swapped.
  2. Stepping Stator Leads:
    • Stator leads are connected in a sequence that shifts alignment by 120 degrees, such as S1 to S2, S2 to S3, and S3 to S1.
  3. Crossing Rotor Leads:
    • Rotor leads R1 and R2 are swapped.
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14
Q

How does the CX/CT Synchro control system operate?

A
  1. Control Transmitter (CX): Turns the rotor’s position into electrical signals and sends them to the CT.
  2. Control Transformer (CT): Detects errors. If it’s not aligned with the CX, it creates an error voltage.
  3. Error Signal: Shows the misalignment between CX and CT rotors.
  4. Servo Motor Control: The error signal drives a motor to adjust the CT rotor to match the CX.
  5. Alignment: The system keeps adjusting until the CT aligns with the CX, making the error signal zero.

This keeps the system precisely controlled by constantly correcting the position.

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15
Q

What device acts as the error measuring device in the CX/CT synchro control system

A

Control Transmitter (CT)

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16
Q

What important function does the servo amplifier perform in the CT/CX synchro system?

A

phase discrimination.

It ensures the correct direction of drive by comparing the phase of the error signal with the reference signal .

17
Q

What would be placed in the chain to enable corrections/deflections to be input to the CX/CT synchro system?

A

Control Differential Transmitter (CDX)

18
Q

Why are two chains employed in a coarse and chain control system?

A

Two chains are employed to improve accuracy

This combination ensures both fast movement and precise alignment.

19
Q

Which device ensures a smooth change-over between chains in a coarse and fine control chain?

A

The Coarse/Fine Changeover Unit (CFCOU) ensures a smooth change-over between the coarse and fine chains.

20
Q

The Coarse/Fine Changeover Unit (CFCOU) is operated by the output of which chain?

A

coarse chain.

21
Q

What is the effect of crossing stator leads S2-S3 or S1 in a synchro chain in terms of rotation and phase?

A

When the transmitter is at datum the receiver status flux is displaced by 120 degrees and rotates in the opposite direction to the input

22
Q

What is the effect of open circuit leads in a synchro chain in terms of rotation and phase?

A

In the datum position and at 180 degrees there will be no flux generated in the receiver as there is no potential difference between lines. Hence no control of the receiver.

If line 2 is open the only flux that will be generated are across lines 1 and 3 so the device can only line up at 90 degrees and 270 degrees.

23
Q

Draw a closed loop position control system and describe how it works

A
  1. Input: Set the desired position.
  2. Error Detection: Compare the actual position with the desired position to find any error.
  3. Error Signal: Generate a signal based on the error.
  4. Motor Adjustment: The error signal drives a motor to correct the position.
  5. Continuous Correction: The system keeps adjusting until the actual position matches the desired position.

This ensures accurate and automatic position control.

24
Q

Draw a closed loop velocity control system and describe how it works

A
  1. Input: Set the desired speed.
  2. Error Detection: Compare the actual speed with the desired speed to find any error.
  3. Error Signal: Generate a signal based on the error.
  4. Motor Adjustment: The error signal drives a motor to adjust the speed.
  5. Continuous Correction: The system keeps adjusting until the actual speed matches the desired speed.

This ensures accurate and automatic speed control.

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