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AN4625

EMC requirements

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4

EMC requirements

4.1

Procedure to evaluate the robustness of the CLT01-38S4

The IEC 61131-2 international standard is the reference to evaluate the CLT01-38S4

robustness. This standard provides all requirements and test conditions for programmable

logic controllers (PLCs) and their associated peripherals. It specifies the electromagnetic

compatibility (EMC) requirements and the nature of the tests to perform and to determine if

the system meets these requirements. The levels of each test depend on the zone where

the system is installed. The most typical industrial environmental levels correspond to zone

B: local power distribution zone and dedicated power distribution zone (see EMC immunity

zones of the IEC 61131-2-Ed2 standard). The following sections deal with the test levels for

this zone.

4.2

ESD tests (IEC 61000-4-2)

Electrostatic discharge test is applied to operator accessible devices. This means that these

tests have to be performed on each connector pin. The required levels are air discharge: ± 8

kV and contact discharge: ± 4 kV.

PLC system continues operating. Temporary degradation of the performance is acceptable

during the test, but the system must recover after the test (criteria “B” according to the

IEC61131-2 standard).

4.3

Burst tests (IEC 61000-4-4)

The fast transient burst tests must be applied to all input pins of the system. A capacitive

clamp-coupling device (50-200 pF) must be used as described in the IEC 61000-4-4

standard. The required burst voltage levels are the analog or DC I/O: ± 1 kV, DC power line:

± 2 kV. PLC system continues operating. Temporary degradation of the performance is

acceptable during the test, but the system must recover after the test (criteria “B” according

to the IEC 61131-2 standard).

4.4

Surge test (IEC 61000-4-5)

Since the voltage surge consists of a single but energetic pulse, the CLT01-38S4 embeds

an overvoltage protection on each point. The absorbed energy complies at least with the

IEC 61131-2 standard requirements. The high energy surge test must be applied on all input

•

Analog or DC I/O: 0.5 kV (differential and common coupling modes)

•

DC power line: 0. 5 kV (differential mode)

•

DC power line: 1 kV (common mode)

The PLC system continues operating. Temporary degradation of the performance is

acceptable during the test, but the system must recover after the test (criteria “B” according

to the IEC 61131-2 standard).