NETA ETT Level 3 flashcards
NETA ETT Level 3 · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Arc flash PPE category 2
- Arc-rated PPE category corresponding to incident energy up to 8 cal/cm²; requires arc-rated shirt and pants or coverall plus face protection and hearing protection.
- Restricted approach boundary
- Boundary within which only qualified persons may work, requiring shock protection; distance depends on voltage and is closer than the limited approach boundary.
- Electrically safe work condition
- State achieved by identifying and disconnecting all sources, locking out, releasing stored energy, and verifying absence of voltage with a tested meter.
- NETA ATS purpose
- Acceptance Testing Specifications define inspections, electrical tests, and acceptable values for new equipment before it is placed into service.
- IEEE C57.152 scope
- Guide for diagnostic field testing of liquid-immersed power transformers, covering test methods and interpretation of results for in-service units.
- IEEE 400.2 scope
- Standard for field testing of shielded power cable systems using very low frequency (0.1 Hz) AC voltage, including withstand and diagnostic tests.
- Meter counts error
- Specification term added to percent-of-reading error; one count equals the smallest digit shown on the display at that range.
- CAT III rating
- Measurement category for distribution-level circuits and fixed installations; withstands higher transient overvoltages than CAT II but less than CAT IV.
- True-RMS meter
- Instrument that computes the root-mean-square value of a waveform, giving correct readings on distorted or non-sinusoidal signals where averaging meters err.
- Polarization Index
- Ratio of insulation resistance at 10 minutes to that at 1 minute; values of 2.0 or higher generally indicate dry, uncontaminated insulation.
- Dielectric Absorption Ratio
- Ratio of insulation resistance at 60 seconds to that at 30 seconds; below 1.25 is questionable and above 1.4 is good for Class A insulation.
- Guard terminal use
- Connection that shunts surface leakage current around the meter so the reading reflects volume resistance of the insulation rather than contamination on surfaces.
- IR temperature correction
- Insulation resistance roughly halves for each 10 °C rise; readings are corrected to a reference temperature such as 40 °C before comparison.
- Kelvin four-wire method
- Measurement technique using separate current and voltage leads so lead resistance is excluded; required for accurate readings below about 1 ohm.
- Copper resistance correction
- Formula R2 = R1 × (234.5 + T2)/(234.5 + T1) converts measured winding resistance to a reference temperature using the copper constant 234.5 °C.
- Transformer turns ratio test
- Verifies the voltage ratio and polarity between windings; deviation beyond about 0.5% from nameplate suggests shorted turns or tap errors.
- SFRA test
- Sweep frequency response analysis compares a transformer's impedance signature to a baseline; shifts in resonance peaks indicate winding deformation or core movement.
- Dissolved gas analysis
- Test of insulating oil for fault gases; acetylene indicates arcing, ethylene indicates thermal faults, and hydrogen indicates partial discharge or corona.
- Doble power factor test
- Insulation power factor test run in configurations CH, CL, CHL, and guarded variants; rising values indicate moisture or contamination in the insulation.
- Breaker contact resistance
- Micro-ohm measurement across closed contacts; rising values versus baseline indicate pitting, misalignment, or loosened connections in the current path.
- Breaker motion analysis
- Records contact travel, velocity, bounce, and damping during operation; slow closing or excessive bounce indicates worn linkages or incorrect spring adjustment.
- Minimum trip voltage
- Test confirming the breaker closes and trips within 70-110% of rated control voltage; failure indicates a weak coil or mechanism problem.
- CT ratio and polarity
- Test injecting primary current and measuring secondary output; P1-to-S1 is subtractive polarity, and reversed polarity causes differential relay misoperation.
- CT saturation knee point
- Point on the excitation curve where secondary current no longer rises proportionally; beyond it, ratio error grows rapidly during faults.
- Relay pickup test
- Slowly increasing current or voltage until the relay operates; the value is compared to the setting sheet to confirm correct calibration.
- Differential relay slope test
- Injects through-current and internal fault current to verify the restraint characteristic; through-current must not trip and internal faults must trip.
- VLF cable testing
- Very low frequency (0.1 Hz) AC withstand test per IEEE 400.2, preferred for aged XLPE cable because it limits space charge compared with DC testing.
- Fall-of-potential method
- Three-point grounding test placing the potential probe at 62% of the distance to the current probe to reduce mutual coupling error in the reading.
- Time domain reflectometry
- Cable fault location method sending a pulse and timing its reflection; distance equals velocity of propagation times time divided by two.
- Surge comparison test
- Applies a steep-front voltage pulse to each motor phase and compares waveforms; differences reveal turn-to-turn or coil-to-coil insulation faults.
- Motor minimum IR
- Per IEEE 43, minimum insulation resistance in megohms equals rated kV plus one, corrected to 40 °C; lower values require drying before energization.
- Motor current signature analysis
- Analyzes the stator current spectrum for sidebands around line frequency to detect rotor bar faults, eccentricity, and bearing problems without disassembly.