ashfordeOU Electrostatic Discharge (avionics/do160/electrostatic-discharge)
Use when the task is DO-160 Section 25 electrostatic discharge (ESD) testing: selecting the equipment category and air discharge test level, computing stored energy and discharge waveform currents from the generator model, checking the discharge count per test point, and judging whether a surface is an applicable test point for personnel accessibility.
Domain quick reference
- DO-160G (RTCA, EUROCAE twin ED-14G) section 25 covers immunity of equipment to electrostatic discharge from personnel handling.
- There is a single equipment category, A, tested at 15 kV air discharge on the equipment bonded to the ground plane. Worked: the category test level function returns 15.0 kV for category A and rejects any other category.
- The discharge generator follows the IEC 61000-4-2 human-body model: 150 pF storage capacitance and 330 ohm discharge resistance.
- Stored energy: E = 0.5 * C * V^2. Worked: 150 pF at 15 kV gives 0.5 * 150e-12 * (15e3)^2 = 0.016875 J (16.9 mJ); at 8 kV it gives 4.8 mJ. Energy scales with the square of the test voltage.
- First peak current: 3.75 A/kV. Worked: 15 kV gives 56.25 A; 2 kV gives 7.5 A.
- Current at 30 ns: 2 A/kV. Worked: 15 kV gives 30 A. Current at 60 ns: 1 A/kV. Worked: 15 kV gives 15 A.
- Rise time window: 0.7 to 1.0 ns. Worked: 0.8 ns is valid; 0.5 ns and 1.2 ns are outside the window.
- RC time constant: tau = R * C. Worked: 330 ohm and 150 pF give 330 * 150e-12 = 49.5 ns.
- Discharges per test point: 10 positive and 10 negative, at the selected level. Worked: 10 and 10 is a valid plan; 9 and 10 is not.
- Test points: surfaces accessible to personnel during normal operation or during maintenance. Connector pins are not applicable test points (DO-160G).
- Pass criteria: equipment operates as specified during and after the discharges with no permanent degradation of performance.
- The actual level and waveform tables are standard data; read them from the current revision of DO-160. This skill is selection and verdict logic only, no standard tables reproduced.
Workflow
- Confirm the applicable DO-160 revision and equipment installation.
- Confirm the equipment category with category_test_level_kv and read the test level (15 kV air discharge for category A).
- Compute stored energy with stored_energy_joules.
- Compute the discharge waveform currents with peak_current_amps, current_at_30ns_amps, and current_at_60ns_amps.
- Check the rise time with rise_time_valid_ns and the network time constant with rc_time_constant_ns.
- Check the discharge plan with discharge_count_valid (10 positive, 10 negative per test point).
- Judge each candidate surface with test_point_applicable.
- Classify the result with pass_verdict.
Pitfalls
- Confusing section 25 ESD with section 22 lightning induced transients (avionics/do160/lightning-protection): ESD uses a 150 pF / 330 ohm air discharge generator at 15 kV, while lightning uses level and waveform set tables on induced transients; do not reuse lightning levels for ESD.
- Confusing ESD with power input testing (avionics/do160/power-input): section 16 covers bus voltage limits, sag and surge transients, and frequency tolerance; ESD discharges are applied to accessible surfaces, not to the power pins.
- Treating ESD as part of the environmental test matrix (avionics/do160/environmental-qualification): section 25 is a standalone EMC section with its own applicability rule (personnel accessibility), not a category letter in the temperature or vibration tables.
- Testing connector pins: DO-160G excludes connector pins as ESD test points; a surface that is a connector pin is not applicable even when accessible.
- Using fewer than 10 discharges per polarity: the plan must include at least 10 positive and 10 negative discharges per test point.
- Applying contact discharge levels from IEC 61000-4-2 without checking the DO-160 category: DO-160 section 25 specifies the air discharge test at 15 kV for category A.
- Using a generator model other than 150 pF and 330 ohm: automotive models (for example 330 pF) do not match the DO-160 human-body model and change the stored energy and waveform currents.
- Judging pass on operation alone: the verdict requires both operation as specified and no permanent degradation of performance.
Behavior contract (gate 3)
The selection and verdict logic is exercised by the gate 3 contract test: scripts/test_electrostatic_discharge.py against scripts/electrostatic_discharge_logic.py (stdlib unittest, offline). Run: python3 scripts/test_electrostatic_discharge.py
Compliance
- Standards referenced, not reproduced: DO-160 text is proprietary (RTCA); summary-only per standards-map.yaml and brief 06.
- The level, waveform, and discharge count tables are standard data; read them from the current revision before use.
- compliance: STANDARDS-REF, gated: false.