Aux 1 Unit 15 Q5

Paralleling AC generators is a critical procedure requiring precision and adherence to safety protocols to ensure a smooth and stable connection to the main switchboard. Here’s a detailed description of the process:

Prerequisites:

• Generator Readiness: Ensure the incoming generator is in good working order, has been warmed up, and is producing the correct voltage and frequency.
• Switchboard Readiness: Confirm that the main switchboard is energized and stable, with the existing generator(s) running and supplying power.
• Qualified Personnel: The paralleling procedure should be carried out by qualified electrical personnel with experience in generator synchronization.

Procedure:

1. Safety First:

• Lockout/Tagout: Implement proper lockout/tagout procedures to prevent accidental energization of the incoming generator or any circuits during the process.
• Communication: Establish clear communication between the person operating the synchronizing panel and the person controlling the incoming generator.
• Protective Equipment: Wear appropriate personal protective equipment (PPE), including insulated gloves and safety glasses.

2. Check Generator Parameters:

• Voltage: Adjust the incoming generator’s voltage to match the busbar voltage using the Automatic Voltage Regulator (AVR).
• Frequency: Adjust the generator’s speed (using the governor control) to match the busbar frequency.
• Phase Sequence: Verify that the phase sequence of the incoming generator matches the busbar phase sequence using a phase sequence indicator.

3. Connect Synchronizing Equipment:

• Synchroscope and Voltmeters: Connect a synchroscope and voltmeters to the incoming generator and the busbar to monitor the phase angle difference and voltage levels.
• Synchronizing Lamps (Optional): If available, connect synchronizing lamps across the corresponding phases of the generator and busbar.

4. Observe Synchronization Parameters:

• Synchroscope: The synchroscope should show a slowly rotating pointer, indicating the phase angle difference. The pointer should rotate clockwise if the incoming generator is running faster (“fast”) and counter-clockwise if it’s running slower (“slow”).
• Voltmeters: The voltage readings on both voltmeters should be approximately equal.
• Synchronizing Lamps: The lamps should brighten and darken alternately, with the flickering slowing down as the phase angles approach coincidence.

5. Adjust Generator Speed and Excitation:

• Matching Frequency: Adjust the generator’s speed to match the busbar frequency, bringing the synchroscope pointer to a slow rotation or near standstill.
• Matching Voltage: Fine-tune the generator’s excitation using the AVR to match its voltage with the busbar voltage.

6. Close Breaker at the Correct Moment:

• Phase Coincidence: Close the generator breaker when the synchroscope pointer is at the 12 o’clock position (or as indicated by the manufacturer), indicating that the phase angles are nearly in phase.
• Lamp Indication (Optional): If using synchronizing lamps, close the breaker when the lamps are dark (or very dim), indicating phase coincidence.

7. Monitor and Adjust:

• Check Parameters: After paralleling, monitor the generator’s voltage, current, frequency, and power output to ensure it’s sharing the load properly with other generators.
• Adjust as Needed: Make any necessary adjustments to the governor or AVR to maintain stable operation and load sharing.

Key Points:

• Safety First: Prioritize safety and follow all electrical safety procedures.
• Precise Synchronization: Ensure that the voltage, frequency, phase sequence, and phase angle are within acceptable limits before closing the breaker.
• Communication: Maintain clear communication between the operator and the person controlling the generator.
• Gradual Load Application: After paralleling, gradually increase the load on the incoming generator to avoid sudden surges and maintain system stability.

By adhering to these procedures and precautions, you can safely and effectively parallel an incoming AC generator to the main switchboard, ensuring a smooth transition and reliable power supply for the vessel’s electrical system.