Surge Test IEC 61000-4-5

Electronic products are tested for Surge immunity to insure their continued reliable operation if subjected to realistic levels of surge voltages. The European Union's EMC Directive currently mandates Surge testing for some products; however, it is expected that virtually all electrical and electronic products will have to be tested for Surge immunity in the near future as a condition for obtaining the CE Mark before shipping products to a member state of the European Union. 

Applicable Standards

Generic Immunity, Product and Product Family Standards require Surge tests be performed in accordance with Basic EMC Standards: IEC 801-5, IEC 61000-4-5 or EN 61000-4-5. Application Note, EMC Standards Overview, provides an overview of European Standards for electromagnetic compatibility, describes how the Standards relate to one another, and lists sources for procuring copyrighted documents. 

Basic EMC Standard 

The Basic EMC Standard for Surge defines the methods of generating consistently reproducible surge voltages for test purposes. They specify generator and coupler/decoupler design and performance in sufficient detail to produce correlatable results between test sites. While the Basic EMC Standard specifies how to perform Surge testing, the Generic, Product and Product Family Standards specify the test levels and pass/fail performance criteria. 

Test Levels 
 

Safety

When performing Surge tests, safety is a primary concern. Surge voltages and currents must be contained to insure they will not appear where they can cause damage to other instruments in the test area. The test pulses used for Surge testing are of sufficient energy to cause components to fragment under fault conditions and become hazardous to personnel in unprotected environments.
 

Coupling Methods

Capacitive Coupling via 9pF (Line to earth) or 18pF (line to line) capacitors is required for coupling surges to AC or DC power mains. These coupling capacitors are typically included as part of a Coupler/Decoupler (C/D) in commercially available Surge simulators. The C/D provides both coupling to the EUT power mains and a decoupler to prevent the surge from appearing on the ac mains connected to other equipment in the lab.

Capacitive Coupling via .5pF capacitors, as well as via alternative devices such as surge arrestors, are used to couple surges onto data, I/O and telecommunication lines. Surge arrestors are the preferred coupler device due to the undesirable loading effects of capacitors particularly at frequencies greater than a few kilohertz. A decoupler is included to prevent the surge from appearing at, and potentially damaging, the auxiliary equipment. 

Waveforms

Waveform Verification

IEC 61000-4-5 requires that the simulator output be verified periodically. High voltage differential surge probes are required for verifying the open-circuit voltage, and a suitable current transformer (Pearson Model 110 or equivalent) is required for verification of the short-circuit current. A digital or storage oscilloscope with 100MHz bandwidth is sufficient for measuring the surge voltage and current waveforms and peaks.

Test Execution

According to IEC 61000-4-5, testing must be carried out according to the manufacturer's test plan, which shall specify:
Generator & other equipment.
Generator Source Impedance.
Repetition rate (one per minute maximum).
Sequence of application of the surge.
Installation conditions.
Operating conditions of EUT.
Number of tests (at least five positive and five negative at each point).
Test levels.
Polarity.
Inputs/outputs tested.
Phase angle of coupling to ac mains.
Internal or external trigger.

EUT Performance Criteria

For Surge tests, the Generic Immunity Standards and Household Appliances Product Family Standard require that products operate as intended after the test. No degradation or loss of function is allowed below a performance level specified by the manufacturer. During the test, degradation is allowed, but not a change in the actual operating status or data storage. Refer to the tables located in the Generic, Product and Product Family Standards for specific Performance Criteria. The product cannot become unsafe under any conditions. 

Surge Simulators

Surge Simulators produced by Thermo KeyTek meet all the simulator requirements of IEC 61000-4-5, including dynamic source impedance, all waveform characteristics, and couplSurge Simulators produced by Thermo KeyTek meet all the simulator requirements of IEC 61000-4-5, including dynamic source impedance, all waveform characteristics, and coupler/decoupler design.