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

Insulation resistance (megohmmeter) testing

Answer

Float voltage comparison at string level

Answer

AC impedance spectroscopy

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

By disconnecting all battery cells and measuring open-circuit voltage

Answer

By applying AC voltage to the DC bus and measuring current

Answer

By comparing individual cell float voltages to the string average

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

Normal aging within manufacturer specification

Answer

Overcharging causing electrolyte boiling

Answer

Correct equalization charge has been applied

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

Battery temperature drops below the freezing point of electrolyte

Answer

Excessive discharge current causing cell reversal

Answer

Loss of electrolyte through the pressure relief valve during normal operation

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

10% above baseline

Answer

20% above baseline

Answer

100% above baseline (double the baseline)

Question 6

What does a DC ground fault in a station battery system directly indicate?

Accepted Answer

An unintentional conductive path between a DC conductor (positive or negative) and earth ground

Answer

A failed battery cell with reversed polarity

Answer

Excessive AC ripple on the DC bus from the charger

Answer

An open circuit in the battery string

Question 7

What level of PPE is required when performing battery acceptance or maintenance testing regardless of the system voltage?

Accepted Answer

Face shield, chemical-resistant gloves, and insulated tools at minimum

Answer

No PPE is required for systems below 50V DC

Answer

Safety glasses only for sealed VRLA battery systems

Answer

Full arc flash suit rated for the prospective fault current