NETA Battery and UPS Systems Testing 3

Question 1

What test method does NETA recommend for identifying high-resistance inter-cell and inter-tier connections in a battery system?

Accepted Answer

Millivolt drop testing under load current

Answer

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.

Question 2

How is a DC ground fault detected in a station battery system during NETA testing?

Accepted Answer

By measuring resistance from the positive and negative bus to ground

Answer

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.

Question 3

A significant increase in a battery cell's internal resistance compared to its manufacturer baseline or initial acceptance test value indicates which condition?

Accepted Answer

Cell degradation, sulfation, or impending failure

Answer

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.

Question 4

What is the condition known as thermal runaway in a VRLA battery system?

Accepted Answer

A self-reinforcing cycle where temperature rise increases charge current, which further increases temperature, potentially leading to failure or fire

Answer

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.

Question 5

According to NETA maintenance testing standards, when should inter-cell connection resistance that has increased above its initial baseline value trigger replacement or remediation?

Accepted Answer

50% above baseline

Answer

NETA and IEEE standards recommend investigating and remediating inter-cell connections when their resistance exceeds 50% above the original measured baseline value.

(NETA) InterNational Electrical Testing Association Certified Technicians Practice Test

(NETA) InterNational Electrical Testing Association Certified Technicians Practice Test

NETA Battery and UPS Systems Testing 3