Electrical Switchgear Verification Flashcards
7 cards from real CCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Electrical Switchgear Verification flashcards as text
During commissioning of a medium-voltage switchgear lineup, which test verifies the mechanical interlock between the main breaker and the bus tie breaker?
Answer: Mechanical interlock integrity test
Mechanical interlock integrity testing confirms that interlocks physically prevent simultaneous closing of incompatible breaker combinations.
What is the purpose of performing a high-potential (hi-pot) test on switchgear bus work prior to energization?
Answer: To verify insulation integrity can withstand overvoltage conditions
Hi-pot testing applies a voltage above rated levels to confirm insulation will not break down under fault or transient overvoltage conditions.
A circuit breaker's minimum trip current in the instantaneous zone is set incorrectly during commissioning. What is the primary risk?
Answer: Failure to clear downstream faults quickly enough to prevent arc flash escalation
An incorrect instantaneous setting may delay fault clearing, allowing arc flash energy to increase significantly and damage equipment.
When verifying draw-out switchgear racking mechanisms, what condition must be confirmed at the 'TEST' position?
Answer: Secondary control circuits remain connected while primary contacts are disconnected
In the TEST position, secondary control wiring stays connected so protective relay and control functions can be exercised without energizing primary circuits.
Which measurement is used to assess the condition of a vacuum interrupter in a medium-voltage circuit breaker?
Answer: Power frequency withstand voltage test across open contacts
A power frequency withstand test across the open contacts of a vacuum interrupter checks whether the vacuum bottle maintains its dielectric integrity.
During switchgear commissioning, a control power transformer (CPT) secondary fuse is found to be undersized. What is the correct action?
Answer: Replace with correctly rated fuse per design drawings before energization
Fuses must match design specifications to ensure proper protection of control circuits; undersized fuses risk nuisance blowing and oversized fuses risk unprotected faults.
What does a contact resistance test on a circuit breaker's main contacts primarily identify?
Answer: High-resistance joints that could cause overheating under load
Elevated contact resistance indicates pitting, contamination, or wear that will generate excessive heat when load current flows.