Practical Marine Electrical Knowledge: Program 8. Electric Propulsion & High Voltage Practice

Summary

This video, part of the 'Practical Marine Electrical Knowledge' series, explores advancements in marine electric propulsion, focusing on high voltage safety, testing, and diesel-electric systems. It discusses the shift toward electric propulsion in modern shipping, especially cruise liners, and the importance of maintaining stable power distribution for both propulsion and hotel services. The video covers high-voltage operations, safety protocols, power management systems, and fault-finding procedures. It also explains the use of synchronous motors, thyristors, frequency converters, and testing techniques, emphasizing the importance of rigorous safety measures in marine electrical systems.

Takeaways

• ⚡ Electric propulsion is increasingly used in modern ships, with a focus on diesel-electric systems and a future shift towards gas turbine-electric propulsion.
• 🛳️ Cruise liners and specialized vessels require significant power for propulsion and hotel services, sometimes exceeding 40 megawatts.
• 🔋 High voltage systems, like 6.6 kV and 11 kV, are used to reduce equipment size and fault levels in modern marine electrical setups.
• ⚠️ Strict safety procedures, including work permits, isolation certificates, and lockout systems, are essential when handling high voltage systems.
• 💡 Testing procedures, such as insulation resistance tests and circuit earth checks, are critical to ensure that circuits are safe before maintenance.
• 🎛️ Power management systems (PMS) control generator sequencing and distribution to optimize fuel economy and ensure reliable power to all ship services.
• 🌊 Synchronous motors, often used for ship propulsion, rely on variable speed drive technology for precise control, especially at low speeds.
• 🔑 Interlocking systems ensure that high voltage equipment is properly earthed and disconnected before access is granted to operators.
• 🔌 Harmonics in the power supply, introduced by converters, require harmonic filters to prevent voltage disturbances and equipment malfunction.
• 🛠️ Regular maintenance, including relay testing and thermal imaging, is vital for detecting issues like hot spots and ensuring the safety of electrical systems.

Q & A

What is the primary focus of the video script?

The video highlights recent advances in marine electric propulsion systems, high voltage operations, safety procedures, and testing in modern ships.

Why is it important to familiarize oneself with the ship's electrical system upon joining?

Familiarity with the electrical system is crucial for effective troubleshooting during blackouts or major breakdowns and ensures safe and efficient operations.

What is a growing trend in modern shipping for propulsion systems?

Diesel-electric propulsion is currently the most common, but there is a growing interest in gas turbine-electric propulsion for future applications.

Why do modern cruise liners require more than 40 megawatts of power?

In addition to propulsion, cruise liners have extensive power needs for passenger services such as entertainment, air conditioning, lifts, galley operations, and telecommunications, which collectively require large power generation.

What safety procedures are essential when dealing with high-voltage equipment?

Strict safety procedures include filling out documentation such as permits to work, risk assessments, electrical isolation certificates, and ensuring isolation points, protective equipment, and warning signs are in place.

How is the insulation resistance of a high-voltage circuit tested?

The high-voltage prod is used to confirm the circuit is dead, and the insulation resistance tester measures between phases and the earth to ensure the circuit is safe and meets the required resistance levels.

What is the role of the Power Management System (PMS) on a ship?

The PMS controls the distribution of power across the ship, manages generator loads for efficiency, and can prioritize essential services like hotel operations while optimizing fuel economy.

What is synchro-phasing in marine propulsion, and why is it used?

Synchro-phasing aligns the rotation of two propeller shafts to reduce hull vibration, especially in cruise ships, and is used under calm sea conditions to improve passenger comfort.

What are thyristors and why are they important in marine electric propulsion?

Thyristors are semiconductor switches used in frequency converters to control the AC current supplied to the motors. They are essential for variable-speed drive systems in modern electric propulsion, enabling efficient speed control.

What are the potential issues with voltage harmonics in marine electrical systems?

Voltage harmonics can cause overheating and malfunction of circuits. Harmonic filters are used to absorb these disturbances, but if they fail, safety procedures must be followed to locate and resolve the fault.