Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
SAE J551-17: Vehicle Electromagnetic Immunity to Power Line Magnetic Fields
SAE J551-17 specifies test methods and procedures for evaluating the immunity of passenger cars and commercial vehicles to magnetic fields generated by power transmission lines and generating stations. This stabilized standard reflects basic and stable technology, making it a reliable reference for electromagnetic compatibility (EMC) testing. The standard covers frequencies commonly encountered in power distribution: 16 2/3, 50, 60, 150, and 180 Hz.
Scope and Key Requirements
The standard applies to vehicles exposed to power line magnetic fields and references SAE J551-1 for general principles and SAE J1812 for Function Performance Status Classification (FPSC). Key elements include test signal definition, functional status classification, region of performance, and test severity levels. Users specify severity levels based on vehicle application, with suggested levels provided in an appendix.
⚠️ Personnel Safety: Test personnel must avoid prolonged exposure to magnetic fields. It is recommended to remain more than 1.5 coil radius away from energized field coils. Verify that all test instrumentation is immune to the generated fields at its location.
Test Facility and Equipment Specifications
The test area must accommodate the vehicle and two magnetic-field generating coils with a minimum diameter of 3 meters. A dynamometer may be used to simulate road usage during testing. Below are the essential equipment specifications per SAE J551-17:
| Equipment | Specification |
|---|---|
| Function Generator | Sinusoidal signals at 16 2/3, 50, 60, 150, 180 Hz |
| Audio Power Amplifier | Bandwidth 16 2/3 Hz–2500 Hz, ~2000 W capability |
| Current Monitor | True rms AC, bandwidth 16 2/3 Hz–2500 Hz |
| Magnetic Field Monitor/Probe | Range 0–50 µT, DC rejection, same bandwidth |
| Magnetic Field Coils | Minimum 3 m diameter, capable of generating required field levels |
🔍 Engineering Insight: Field characterization is performed without the vehicle at incremental levels (e.g., 10 µT steps) up to the desired test level for both longitudinal and transverse axes. This data should be recorded and can be reused for the same coil separation. Characterization is recommended at least semi-annually.
Field Characterization and Test Procedure
The test procedure involves orienting the coils coaxially, placing the vehicle between them, and applying the current corresponding to specified test levels. The vehicle is exposed for a minimum of 30 seconds at each field level and frequency. Degradation in performance is monitored, and if observed, field strength is reduced to determine the susceptibility threshold. Testing must be performed for both longitudinal and transverse axes.
The standard is stabilized, meaning it will no longer undergo periodic reviews for currency. Users are responsible for verifying references and continued suitability of technical requirements. Newer technology may exist, but this document provides a solid baseline for immunity testing.
Frequently Asked Questions
1. What is the purpose of SAE J551-17?
It provides standardized test methods to ensure vehicles maintain electromagnetic immunity to magnetic fields from power lines and generating stations, reducing risks of electronic malfunctions under real-world conditions.
2. What frequencies are tested?
The standard specifies 16 2/3, 50, 60, 150, and 180 Hz. These correspond to common power distribution frequencies and their harmonics.
3. Why is the standard stabilized?
The technology is considered basic and stable, so the document no longer requires periodic updates. It remains a valid reference but may not reflect newer developments.
