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SAMPLE DRAFT EMC TEST PLAN

Contents:

  1. General
  2. Configuration of EUT during testing
  3. Operation conditions of EUT during testing
  4. Specification of acceptance criteria
  5. Test description
  6. Immunity Requirements
  7. Emission requirements

 

1. General

Prior to the performance of the EMC tests, an EMC test plan has to be established. It shall contain as a minimum the elements given in the following paragraphs. The example provided below relates to laboratory, measurement and control equipment and is drawn from IEC 1326. Similar considerations should be applied for other equipment such as ITE, ISM, Appliances etc. Specific requirements for other equipment is given in other examples and the information is under preparation.

2. Configuration of EUT during testing.

2.1 General

Measurement, control and laboratory equipment often consist of systems with no fixed configuration. The kind, number, and installation of different subassemblies within the equipment may vary from system to system. Here it is reasonable, and also recommended, not to test every possible arrangement.

To realistically simulate EMC condition (related both to emission and immunity) the equipment assembly shall represent a typical installation. Such tests shall be carried out as type tests under normal conditions.
 

2.2 Composition of EUT

All devices, racks, modules, boards etc. significant to EMC and belonging to the EUT shall be documented.
 

2.3 Assembly of EUT

If an EUT has a variety of internal and external configurations, the type tests shall be done with one or more typical configurations that represents normal use. All modules shall be tested. The rationale for this selection shall be documented in the EMC test plan.
 

2.4 Cable interfaces to be tested

A sufficient number but at least one of each kind of cable interface shall be connected and tested.
 

2.5 Auxiliary equipment

A list of all auxiliary equipment (peripheral devices) shall be provided. At least one of each type of devices shall be selected to simulate actual operation conditions and to ensure that all the different types of termination are covered.
 

2.6 Cabling and grounding

The cables and ground shall be connected to the EUT in accordance with the manufacturer’s specifications. There shall be no additional earth connections.

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3 Operation conditions of EUT during testing

3.1 Operation modes

A selection of representative operation modes shall be made, considering that not every but only the most typical functions of the electronic equipment can be tested, e.g. for analogue signals at 10%, 50% and 90% magnitude, and for digital signals typical impulse trains. Worst case operating conditions for EMC shall be selected.
 

3.2 Environmental conditions

The tests shall be carried out within the manufactures specified operating environmental range (e.g. ambient temperature, humidity, atmospheric pressure) and at the rated supply voltage.
 

3.3 Test software

The test software used for different modes of operation shall be documented. This software shall represent a typical worst case operating mode.

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4. Specification of acceptance criteria

Pass/fail criteria for each port and test shall be specified. The acceptance criteria shall be specified as quantitative values where possible.

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5. Test description

Each test to be applied shall be specified in the EMC test plan. The description of the tests, the test methods, the characteristics of the tests and the test set-ups are given in basic standards which are referred to in 6.2 and 7.2. The contents of these basic standards need not be reproduced in the test plan, however additional information needed for the practical implementation of the tests are given in this standard, In some cases the EMC test plan should specify the application in detail.

NOTE - Not all known disturbance phenomena have been specified for testing purposes in this standard, but only those which are considered as most critical.

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6. Immunity Requirements

6.1 Conditions during the tests

The configuration and modes of operation during the tests shall be precisely noted in the test report.

Tests shall be applied to the relevant ports according to table 1.

The tests shall be conducted in accordance with the basic standards. The tests shall be carried out as single tests. If additional methods are required the method and rationale shall be documented.

Measuring instruments may be specified as overall accuracy or deviation from a normal reading without interference.
 

6.2 Minimum immunity test requirements

The minimum immunity testing requirements are as given in table 1.

NOTE

  • Tests for earth ports are not specified separately because dedicated protection earth ports are covered by and tested as AC power ports
  • signal earth connections are covered by and tested as I/O-ports.

Port

Phenomenon

Basic standard

Test value

Enclosure Electrostatic discharge (ESD)
EM Field		 IEC 61000-4-2
IEC 61000-4-3		 4kV contact/6kVair
3V/m
AC Power Voltage Interrupt
Burst
Surge
Conducted Signals		 IEC 61000-4-11
IEC 61000-4-4
IEC 61000-4-5
IEC 61000-4-6		1 cycle/100%
1 kV
0.5kV 1)/1kV2)
3 V
DC Power Burst
Surge
Conducted Signals		 IEC 61000-4-4
IEC 61000-4-5
IEC 61000-4-6		 1 kV
0.5 kV1)/1 kV2)
3 V
I/O Signal/Control Burst
Surge
Conducted Signal		 IEC 61000-4-4
IEC 61000-4-5
IEC 61000-4-6		 0.5 kV 4)
1 kV 2) 3)
3 V 4)
1) line to line. 2) line to ground  3) only in case of long distance lines 4) only in case of lines > 3m

Table 1: Minimum immunity test requirements

Equipment shall not become dangerous or unsafe as a result of the tests defined in this standard.
 

6.3 System and application aspects

If higher levels or tests of other phenomena under system aspects are necessary for specific applications, the immunity shall be increased or mitigation measures in the installation shall be applied.
 

6.4 Random aspects

The acceptance criterion shall be observable during the test, and not a random phenomenon. The duration of the test and number of tests shall be sufficient to test each function of the EUT. Special care must be given to ensure that this is covered with automatic (processor) controlled EUT’s.

NOTE - For instance in the case of ESD testing of a digital device the EUT should be exposed to at least 10 discharges at each condition, test point and test level to exclude random effects. In case of burst testing it may be advisable to extend the testing time to more than 1 min.
 

6.5 Performance criteria

The general principles (performance level) for the evaluation of the immunity test results are the following:

Criteria A: During testing normal performance within the specification limits.

Example 1:
If electronic equipment has a central processing entity and is required to work with high reliability, the processor shall operate without any degradation.

Criteria B: During testing temporary degradation or loss of function or performance which is self-recoverable.

Example 1:
A data transfer is controlled/checked by parity check or by another means. In the case of malfunctioning, such as caused by a lightning strike, the data transfer will be repeated automatically. The reduced data transfer rate at this time is acceptable.

Example 2:
During test time an analogue function value deviates for an allowed margin. After test the deviation vanishes.

Example 3:
In the case of a monitor, only used for man-machine monitoring, it is acceptable that some degradation takes place for a short time, such as flashes during the BURST application.

Criteria C: During testing temporary degradation or loss of function or performance which requires operator intervention or system reset.

Example 1:
In the case of an interruption in the mains longer than the specified buffer time, the power supply unity of the equipment is switched off. The switch on may be automatic or carried out by the operator.

Example 2:
After a program interruption caused by a disturbance the processor functions of the equipment have to stop at a safe position, not left in a ‘crashed state’. Operator’s decision prompts may be necessary.

Example 3:
The test results in an opening of an over current protection device which is replaced or reset by the operator

Criteria D: Degradation or loss of function which is not recoverable due to damage to equipment or software, or loss of date.

For acceptance levels B and C, the EUT has passed the tests if it has shown its intended immunity throughout the period of application of the test signal and at the end of the tests the EUT fulfils the functional requirements established in the technical product specification.

Because it is not possible to state only one acceptance level for each phenomenon, the following guidance is given:

  1. It has to be checked which function equipment normally fulfils.
  2. The function of the device in relation with the phenomenon determines the acceptance level.
An example for possible combinations is given in table 2.

NOTE - For type testing it is highly recommended to choose acceptance level A for all phenomena and all tests. However acceptance level B and /or C may be accepted provided that both the specification and the test report highlight such deviation(s) for the relevant combination(s) of function and test.

Standard SafetyData acquisition Human machine interface Others
IEC 61000-4-2 a b b c
IEC 61000-4-3 a a a b
IEC 61000-4-4 a b b b
IEC 61000-4-5 a b b c
IEC 61000-4-6 a a a c
IEC 61000-4-11 a b c c

Table 2: Example of evaluation of immunity test results.

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7. Emission requirements


In some countries, certain control devices are legally exempted from mandatory emission requirements. Where exempted by national regulation, the emission requirements stated in this standard do no apply.
 

7.1 Conditions during measurements

The measurements shall be made in the operating mode producing the highest emission in the frequency band being investigated which is consistent with normal operating conditions (see clause 5).

NOTE - The conducted emission limits covered by this specification are given on a port by port basis.

Measurements shall be performed in well-defined and reproducible conditions for each type of emission.

The description of the tests, the test methods, and the test set-ups are given in the reference standards as stated in table 3 and 4. The contents of the reference standards are not reproduced here, however modifications or additional information needed for the practical implementation of application of the tests are given in this standard.

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