🔍 Key Concepts
• Instantaneous overload relay vs thermal overload relay – how they behave when current suddenly rises
• Typical protection requirements for motors driving a fan, pump, winch, and machine tool
• Risk of sudden jamming, shock load, or line-parting and the need for very fast electrical trip
💭 Think About
• For each device, ask yourself: if it suddenly jams or is overloaded, which one creates the most immediate danger to people, structure, or equipment?
• Which of these motors is most likely to experience very high current instantly (like a short or hard stall) rather than a slow, gradual overload?
• Which devices can usually tolerate a brief overload without serious hazard, and which device cannot?
✅ Before You Answer
• Verify which load is most likely to be subjected to sudden mechanical locking or shock loads in normal use.
• Check which equipment, if it fails to stop immediately on overload, could damage the ship, cargo, or seriously injure personnel.
• Confirm which motors are more commonly protected by thermal (time‑delay) overloads versus those needing instantaneous tripping.