Overview
ISO 7637-2:2011, "Road vehicles - Electrical disturbances from conduction and coupling - Part 2: Electrical transient conduction along supply lines only," defines bench test methods to evaluate and ensure compatibility of automotive equipment with conducted electrical transients on 12 V and 24 V vehicle power systems. The standard covers both transient emissions (sources that generate disturbances) and transient immunity (equipment resistance to injected pulses). It applies to passenger cars and commercial vehicles regardless of propulsion (ICE or electric) and includes a function performance status classification for immunity (see Annex A).
Key topics and technical requirements
- Scope and applicability: Bench tests for devices installed on nominal 12 V and 24 V electrical systems; applies to all road vehicles independent of propulsion.
- Test procedures: Detailed setups for voltage transient emissions and transient immunity tests using standardized bench configurations.
- Measurement instrumentation: Use of oscilloscopes, voltage probes and waveform acquisition equipment with appropriate sampling rates and triggering to capture full transient waveforms.
- Artificial network: Required artificial network to standardize impedance loading when measuring emissions.
- Test hardware: Specification of elements such as shunt resistor, switch representation (ignition/relay), power supply layout and grounding to mimic vehicle installation.
- Pulse generation: Use of a test pulse generator to inject characteristic pulses (3a/3b and other pulses described) with peak voltage adjustment tolerances (+10%/0%). Note: pulses 4, 5a, 5b are now specified in ISO 16750-2 and ISO 21848 (see foreword).
- Environmental and setup parameters: Typical ambient temperature (23 ± 5 °C) and supply voltages used in tests (U = 13.5 ± 0.5 V for 12 V systems; U = 27 ± 1 V for 24 V systems). wiring, grounding, and DUT placement requirements to ensure repeatable laboratory results.
- Reporting and evaluation: Recordings of highest positive and negative waveform acquisitions (minimum ten acquisitions unless stated), and evaluation per Annex B.
Practical applications and users
Who uses ISO 7637-2:2011:
- Automotive OEMs and vehicle system integrators defining supplier test plans and vehicle-level EMC requirements.
- Tier‑1 suppliers and component manufacturers validating electronic control units (ECUs), relays, actuators and sensors for conducted transient immunity and emissions.
- EMC test laboratories performing standardized bench tests to provide repeatable, comparable results.
- Design and compliance engineers for early-stage design verification, failure analysis, and supplier agreements.
Practical benefits:
- Identifies susceptibility to supply-line transients and helps prevent in-vehicle malfunctions.
- Provides repeatable bench procedures for device qualification and supplier verification.
- Supports documentation of function performance status after transient exposure.
Related standards
Keywords: ISO 7637-2:2011, electrical transients, automotive EMC, conducted immunity, 12 V, 24 V, artificial network, transient emissions, transient immunity, bench testing.