HV Exit Exam • Set 7 Question 16 of 30
The electrical contact resistance between closed circuit breaker contacts is least affected by which of the following parameters?
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Direct Answer
Option D: Surrounding ambient air temperature
Contact resistance R_c is primarily governed by mechanical contact force, surface roughness/contact area, and oxide films. Moderate changes in ambient temperature have negligible direct effect on R_c.
All Options
A
Mechanical contact pressure applied by springs
B
Surface profile and contour of the contact faces
C
Surface oxidation and contamination films
D
Surrounding ambient air temperature
(Correct Answer)
Detailed Explanation & Context
Contact resistance R_c is primarily governed by mechanical contact force, surface roughness/contact area, and oxide films. Moderate changes in ambient temperature have negligible direct effect on R_c.
Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • High Voltage Safety Officer & Switchgear Operations (HV).
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