QETPP key terms

A DC voltage is applied between an insulated conductor and ground (or between windings) to measure resistance; low values suggest moisture, contamination, or degradation.

Ratio of insulation resistance at 10 minutes to 1 minute; indicates insulation condition and moisture susceptibility; typically >2 acceptable for rotating machines, but limits vary by class.

Applies a specified AC or DC overvoltage for a set time to verify insulation can withstand transient or operating stress without breakdown; can be destructive if misapplied.

Applies incremental DC test voltages in steps and records insulation resistance at each step; a downward trend can reveal insulation weakness that a single-voltage test misses.

Injects a high DC current through closed contacts and measures the micro-ohm voltage drop; compares results to manufacturer limits or previous baseline to detect pitting, contamination, or loose joints.

Records open/close times, simultaneity, bounce, and travel of breaker contacts using a timing analyzer; verifies mechanical and trip-coil performance against manufacturer specifications.

A device that monitors current, voltage, frequency, or other quantities and initiates trip or alarm signals when settings are exceeded; coordination depends on correct settings and testing.

Applies simulated current and voltage signals to relay terminals to verify pickup, timing, and logic without energizing primary equipment; requires accurate source and lead connections.

Injects current through the primary conductor and current transformer to verify the entire protection chain, including CT ratio, wiring, relay response, and trip circuit.

Verifies the turns ratio and relative polarity of a current transformer by injecting a known primary or secondary signal and measuring the output; errors affect metering and protection.

Measures the connected secondary load (VA and impedance) on a current transformer to ensure it does not exceed the CT's rated burden, which could cause saturation and protection misoperation.

Analyzes protective device time-current characteristics to select settings that isolate faults with minimal outage while preserving upstream selectivity and limiting equipment damage.

Calculates available fault currents at each bus under defined system conditions; results set equipment ratings and protective device interrupting requirements.

Estimates incident energy and arc flash boundary at working distances, enabling selection of PPE and labeling under standards such as NFPA 70E and IEEE 1584.

A documented procedure that isolates energy sources, applies locks and tags, and verifies de-energization before work; prevents unexpected energization or release of stored energy.

Confirms a circuit is at zero energy by testing with a known-good voltage detector, checking all conductors and phases, and re-testing the detector after use.

Clothing and equipment such as arc-rated garments, face shields, gloves, and hearing protection selected from an arc flash and shock risk assessment to reduce injury severity.

Applies a known voltage to one winding and measures the induced voltage on another to verify turns ratio and polarity; deviations can indicate shorted turns or tap problems.

Compares transformer winding impedance over a range of frequencies to a baseline; shifts in the signature can indicate winding deformation, core movement, or bushing issues.

Samples insulating oil and measures dissolved gases; gas concentrations and ratios help diagnose overheating, arcing, partial discharge, or paper degradation in oil-filled transformers.

Detects small electrical discharges within insulation by measuring high-frequency current pulses, acoustic signals, or electromagnetic emissions; PD can precede insulation failure.

Measures dielectric losses in insulation as the ratio of resistive to capacitive current; increases can indicate moisture, contamination, or aging in bushings and windings.

Uses an infrared camera to find abnormal temperature rises in energized equipment; hot connections, overloads, and phase imbalances appear as thermal anomalies compared with similar components.

Measures voltage sags, swells, harmonics, transients, and unbalance over time to diagnose equipment misoperation and verify compliance with standards such as IEEE 519.

Deviation of a voltage or current waveform from a pure sine wave, quantified by total harmonic distortion (THD); high THD can overheat transformers, motors, and neutral conductors.

Measures resistance to remote earth of a grounding system, often by fall-of-potential or clamp-on methods; low resistance limits step and touch voltages during faults.

A three-point method that injects current into a ground electrode and measures voltage at varied probe spacings to determine earth resistance, avoiding the influence of nearby electrodes.

Uses the Wenner four-pin method or similar to measure earth resistivity at depth; results inform ground grid design and electrode spacing.

Discharges a stationary battery at a constant load to a defined end voltage and compares delivered capacity with rated ampere-hours; identifies aging cells and verifies backup time.

Compares an instrument's indication with a reference standard of known uncertainty and documents the deviation; adjusts or assigns correction factors when required.

A quantified range around a measured value that accounts for instrument accuracy, resolution, environmental effects, and procedure; it determines whether results meet tolerances.

An unbroken chain of calibrations linking an instrument's measurements to national or international standards, each step documented with stated uncertainty.

Test results recorded before and after adjustment or repair; as-found shows equipment condition at arrival, as-left shows condition after work and supports acceptance decisions.

A defined set of measurements and functional checks performed before energization or handover to confirm equipment meets specifications, standards, and contract requirements.

The process of verifying and documenting that installed systems operate safely and meet design intent, including component tests, functional tests, and integrated system tests.

Operates equipment through its intended control sequences and interlocks to confirm correct response, often including trip circuits, alarms, and remote indications.

A reference set of measurements or performance data taken when equipment is known to be in good condition; later results are compared to it to detect trends.

Plots test results over time to distinguish normal aging from sudden deterioration; requires consistent test methods, conditions, and calibrated instruments.

The InterNational Electrical Testing Association's Acceptance Testing Specifications, which define recommended tests and tolerances for electrical power equipment and systems.