Immunity

Introduction

The purpose Immunity testing of a electrical equipment is to evaluate its resistance to external electromagnetic interference (EMI).

Overview

Immunity is categorized as

• Electrostatic Discharge (ESD)
  • High spike of voltage wave form generated by external source such as a human finger conducted through either spark in the air or physical contact
• Radiated Immunity (RI)
  • Electromagnetic interference generated by external source such as a hobbyist ham radio picked up by the radio antenna on the electrical equipment
• Conducted Immunity (CI)
  • Noisy voltage waveform generated by external source such as an external power supply picked up by the power cable to the electrical equipment.

Summary & Conclusion

• Electronic product level of resistance towards electrostatic discharge (i.e body or machine static discharge) is tested against ESD standards.
• Electronic product level of resistance towards radiated interference is tested against RI standards
• Electronic product level of resistance towards conducted interference is tested against CI standards

Immunity of an electronic product in the every increasing electromagnetic noisy environment is essential for product reliability.