Describe a typical emergency power source for cargo ships, list essential services supplied simultaneously, and explain periodic testing?

flowchart TD
    A[Emergency Diesel Generator] -->|Supplies| B[Emergency Switchboard]
    B --> C[Emergency Lighting]
    B --> D[Navigation Lights]
    B --> E[Internal Communication]
    B --> F[Fire Detection & Signals]
    B --> G[Radio Installation]
    H[Periodic Test] -->|Simulated Blackout| A
    H -->|On-Load Verification| B

• Typical power source: diesel generator above the uppermost continuous deck with independent fuel supply and starting means
• Location: above uppermost continuous deck, accessible from open deck, not forward of collision bulkhead
• Independence: fire or casualty in main machinery spaces must not interfere with emergency supply
• Essential services: emergency lighting, navigation lights, internal communication, fire detection, emergency signals, radio installation
• Duration: at least 3 hours simultaneous operation for cargo ships under 5000 tons
• Testing: periodic on-load test with simulated blackout, including automatic start verification
• Governing instrument: SOLAS II-1 Reg 43