HV Exit Exam • Set 7 Question 12 of 30

A 'Kick fuse' (time-lag or slow-blow fuse) is characterized by having:

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Direct Answer

Option C: Inverse time-current characteristics

Time-delay (slow-blow) fuses exhibit an inverse time-current characteristic: high overload currents trip rapidly while harmless motor starting current surges pass without blowing.

All Options

Square law instantaneous response

Linear fast response

Inverse time-current characteristics (Correct Answer)

Constant delay regardless of current

Detailed Explanation & Context

Time-delay (slow-blow) fuses exhibit an inverse time-current characteristic: high overload currents trip rapidly while harmless motor starting current surges pass without blowing.

Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • High Voltage Safety Officer & Switchgear Operations (HV).

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Q1 High Rupturing Capacity (HRC) fuses provide the most effective and rapid protection under conditions of: Q2 For high-speed motor circuit breakers, the total closing time from command signal to contact touch is typically in the order of: Q3 Which type of protective relay is commonly used to protect electric motors against continuous moderate overload? Q4 According to Preece's Law, the fusing current (I) of a fuse wire is related to its wire diameter (D) by the relationship: Q5 In a circuit breaker contact gap, ionization of the medium is NOT facilitated by: Q6 An ideal fuse wire material should possess which combination of physical properties? Q7 For extra-high-voltage (EHV) transmission networks above 220 kV, which circuit breaker type is predominantly selected? Q8 The number of power-frequency AC cycles in which a modern high-speed circuit breaker completes its tripping and arc clearing operation is: Q9 Which of the following metals is best suited for manufacturing precision HRC fuse elements due to its resistance to oxidation and low specific resistance? Q10 In a circuit breaker, the current that is flowing through the contacts at the precise instant of contact separation is known as the: