Practical Marine Electrical Knowledge: Program 4. Motors and Starters

Summary

This video, part of a series on Practical Marine Electrical Knowledge, focuses on three-phase cage induction motors. It covers essential testing techniques, including continuity and insulation resistance tests, and demonstrates how to dry out motors exposed to water. The program also explores single-phase motors, various motor starters, and critical electrical safety practices. Maintenance strategies based on company policies and the importance of vibration monitoring are emphasized. Viewers will learn about common motor faults, troubleshooting steps, and specialized applications, all aimed at enhancing operational safety and efficiency on ships.

Takeaways

• 🔌 Understanding the electrical components of three-phase induction motors is crucial for effective maintenance and troubleshooting.
• ⚡ Always isolate electrical circuits before performing any maintenance work to ensure safety.
• 🚨 The layout of the main and emergency switchboards is essential knowledge for any crew member on a ship.
• 🧪 Insulation resistance testing is key to diagnosing issues in electric motors, especially after exposure to water.
• 💧 When drying out a water-drenched motor, use current injection from a welding set while carefully monitoring temperature.
• 🔍 Regularly check and clean the terminals, cables, and other components to prevent failures in electric motors.
• 🚀 For single-phase motors, specific maintenance procedures include checking the centrifugal switch and cleaning the commutator.
• 🔄 Star-delta starters and auto-transformer starters help manage starting currents effectively, preventing damage to motors.
• 🛠️ Regular inspection of starter control systems and contactors is necessary to ensure they operate correctly.
• 📚 It's recommended to consult the accompanying book, 'Practical Marine Electrical Knowledge,' for more detailed study.

Q & A

What is the primary focus of the marine electrical knowledge program?

The primary focus is on practical knowledge regarding the maintenance and testing of three-phase cage induction motors used on ships.

What are the most commonly used electric motors on board ships?

The most commonly used electric motors on board ships are three-phase squirrel cage rotor induction motors.

What is the importance of understanding the layout of the main and emergency switchboards?

Understanding the layout is crucial for effective troubleshooting during blackouts or major breakdowns.

What is the golden rule of electrical safety before working on installations?

Before any work is done, the circuit must be isolated by removing supply fuses or locking the circuit breaker in the open position.

What methods are used for maintaining motors on board ships?

Modern maintenance relies on vibration monitoring and insulation resistance trends to schedule maintenance and detect developing issues without removing motors from service.

What are some common faults that can occur in electric motors?

Common faults include overheating, failure to start, running at low speed, earth faults, and single phasing faults.

How should a motor that has been drenched in water be dried out?

It should be washed with fresh or distilled water, cleaned with approved electrical cleaning fluid, and dried using current injection from a welding set.

What types of single-phase motors are discussed in the program?

The program discusses commutator motors and capacitor start motors.

What is the function of motor starters like Direct Online and Star Delta starters?

Motor starters are used to start and stop motors, while also providing protection against overcurrent, undervoltage, and single phasing conditions.

What precautions should be taken when working with electrical circuits?

Always isolate the circuit, post warning signs, and verify the circuit is dead using a voltmeter or line tester before starting work.