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Questions and Answers
Explain how the use of resistance and inductance in the synchroscope's armature windings creates a rotating magnetic field.
Explain how the use of resistance and inductance in the synchroscope's armature windings creates a rotating magnetic field.
The inductance shifts the current by 90 degrees relative to the current in the resistance. These phase-shifted currents, when applied to the two armature windings, generate a rotating magnetic field necessary for the synchroscope's operation.
Describe what the direction of the synchroscope pointer's rotation indicates about the incoming machine's frequency relative to the system's frequency. Specifically, what does anti-clockwise and clockwise rotation mean?
Describe what the direction of the synchroscope pointer's rotation indicates about the incoming machine's frequency relative to the system's frequency. Specifically, what does anti-clockwise and clockwise rotation mean?
Anti-clockwise rotation means the incoming machine's frequency is lower, while clockwise rotation indicates it is higher than the system's frequency.
Why is the command to close the incoming alternator breaker issued at the one o'clock position on the synchroscope, rather than waiting for perfect synchronization at the twelve o'clock position?
Why is the command to close the incoming alternator breaker issued at the one o'clock position on the synchroscope, rather than waiting for perfect synchronization at the twelve o'clock position?
The command is issued at the one o'clock position to compensate for the time delay between issuing the command and the actual closure of the breaker. Issuing the command at the one o'clock position ensures the machine connects to the busbars when the pointer reaches the two o'clock position.
How does the synchroscope utilize principles analogous to an AC motor? What specific component and effect are most relevant?
How does the synchroscope utilize principles analogous to an AC motor? What specific component and effect are most relevant?
Explain how the alternating polarity of the poles, driven by the red and yellow phases of the incoming machine, contributes to the synchroscope's function.
Explain how the alternating polarity of the poles, driven by the red and yellow phases of the incoming machine, contributes to the synchroscope's function.
Flashcards
Synchroscope
Synchroscope
An instrument using AC motor principles to indicate synchronism between two AC sources.
Synchroscope Connection Points
Synchroscope Connection Points
The synchroscope connects to these phases to compare the incoming machine with the bus.
Inductance in Synchroscope
Inductance in Synchroscope
Causes a phase shift in current within the synchroscope's armature windings.
Anti-Clockwise Rotation
Anti-Clockwise Rotation
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Breaker Closure at One O'Clock
Breaker Closure at One O'Clock
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Study Notes
- Synchroscopes use AC motor principles.
- Two ports connect across any two phases, usually red and yellow, of the incoming machine.
- Armature windings get power from similar phases, like red and yellow, in the switchboard bus.
- The armature has two parallel windings.
- One winding half has resistance in series, the other has inductance.
- Inductance shifts current flow by 90 degrees relative to the resistance current.
- These currents create a rotating magnetic field when fed to the two armature windings.
- Pole polarity alternates north and south with red and yellow phase changes of the incoming machine.
- The rotating field interacts with the poles, moving the rotor clockwise or anti-clockwise.
- The synchroscope pointer rotates at the same time.
- Pointer direction shows the incoming machine's speed or frequency.
- Anti-clockwise rotation means the incoming machine's frequency is lower.
- Clockwise rotation means the incoming machine's frequency is higher.
- When the pointer rotates clockwise, issue a command to close the incoming alternator breaker around the one o'clock position.
- When the pointer rotates anti-clockwise, issue a command to close the incoming alternator breaker around the one o'clock position.
- Issuing the command at the one o'clock position connects the machine to the busbars when the pointer reaches the two o'clock position.
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Description
Synchroscopes operate like AC motors, using two ports to connect across phases. Armature windings powered by phases in the switchboard bus, consist of parallel windings with resistance and inductance. This creates a rotating magnetic field, interacting with poles to move the rotor and synchroscope pointer, indicating frequency differences.
