HV Exit Exam • Set 7 Question 4 of 30
According to Preece's Law, the fusing current (I) of a fuse wire is related to its wire diameter (D) by the relationship:
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Direct Answer
Option C: I ∝ D^(3/2) (or D^1.5)
Preece's formula (I = k·d^(1.5)) establishes that the fusing current for a round conductor is proportional to the diameter raised to the power of 3/2.
All Options
A
I ∝ 1 / D
B
I ∝ D
C
I ∝ D^(3/2) (or D^1.5)
(Correct Answer)
D
I ∝ D²
Detailed Explanation & Context
Preece's formula (I = k·d^(1.5)) establishes that the fusing current for a round conductor is proportional to the diameter raised to the power of 3/2.
Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • High Voltage Safety Officer & Switchgear Operations (HV).
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