Battery and UPS Systems Testing Flashcards
7 cards from real NETA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Battery and UPS Systems Testing flashcards as text
What test method does NETA recommend for identifying high-resistance inter-cell and inter-tier connections in a battery system?
Answer: Millivolt drop testing under load current
Measuring the millivolt drop across each inter-cell connection under a known discharge current identifies high-resistance connections that would cause excessive voltage drop under load.
How is a DC ground fault detected in a station battery system during NETA testing?
Answer: By measuring resistance from the positive and negative bus to ground
Measuring insulation resistance from the positive bus to ground and the negative bus to ground detects unintended conductive paths to earth ground in the DC system.
A significant increase in a battery cell's internal resistance compared to its manufacturer baseline or initial acceptance test value indicates which condition?
Answer: Cell degradation, sulfation, or impending failure
Rising internal resistance relative to baseline is a key indicator of cell degradation, sulfation of plates, or electrolyte loss, signaling that the cell is approaching end of life.
What is the condition known as thermal runaway in a VRLA battery system?
Answer: A self-reinforcing cycle where temperature rise increases charge current, which further increases temperature, potentially leading to failure or fire
Thermal runaway occurs when elevated temperature reduces internal resistance, causing the charger to deliver more current, which generates more heat in a self-reinforcing destructive cycle.
According to NETA maintenance testing standards, when should inter-cell connection resistance that has increased above its initial baseline value trigger replacement or remediation?
Answer: 50% above baseline
NETA and IEEE standards recommend investigating and remediating inter-cell connections when their resistance exceeds 50% above the original measured baseline value.
What does a DC ground fault in a station battery system directly indicate?
Answer: An unintentional conductive path between a DC conductor (positive or negative) and earth ground
A DC ground fault is an unintended low-resistance path from a DC bus conductor to earth ground, which can cause protective relay misoperation and represents a safety hazard.
What level of PPE is required when performing battery acceptance or maintenance testing regardless of the system voltage?
Answer: Face shield, chemical-resistant gloves, and insulated tools at minimum
Battery systems present chemical hazards (acid, hydrogen gas) and high short-circuit current risks; NETA and NFPA 70E require face shields, chemical-resistant gloves, and insulated tools at minimum for all battery work.