Immunity tests in FCC/CE certification of a product is conducted mainly to make sure that the product can work under the influence of disturbances present in the use-case environment.
General Immunity tests are –
- RF electromagnetic field (Radiated Immunity)
- RF Common mode (Conducted Immunity)
- Electrostatic Discharge (ESD)
- Electrical Fast Transients (EFT)
- Surge (Lightning)
- Voltage DIP & Interruptions
- Power frequency magnetic field
Applicability of the immunity tests on the specific product depends on the use case scenario of the product. For example, in case of Radio and ancillary equipments, Surge Immunity tests are applicable only for base station equipments, whereas Radiated Immunity tests are applicable for base station as well as Mobile & portable equipments.
The immunity tests are specified with different level with the immunity requirement increasing as the levels go up. For example, ESD tests for contact discharge are specified with four different levels .
- Level 1 – 2kV
- Level 2 – 4kV
- Level 3 – 6kV
- Level 4 – 8kV
The performance criteria for the product during immunity tests are divided into 4 categories –
- Normal performance within limits specified by the Product user manual.
- Temporary loss of function or degradation of performance which ceases after the disturbance ceases, and from which the equipment under test recovers its normal performance, without operator intervention.
- Temporary loss of function or degradation of performance, the correction of which requires operator intervention.
- Loss of function or degradation of performance which is not recoverable, owing to damage to hardware or software, or loss of data.
Depending on the applicable immunity tests, test levels & required performance criteria, the protection circuits needs to be designed for the product to be compatible with these standards.