Siemens S5-135U/155U appendix Most Important Basic Rules for Ensuring EMC

Installation Guidelines

3.1.2The Most Important Basic Rules for Ensuring EMC

It is often sufficient to comply with a few elementary rules for ensuring EMC. When installing the control system, therefore, observe the following five basic rules.

When installing the programmable controllers, provide large-area good quality grounding of the inactive metal parts (see Section 3.2).

SMake a large-area low-impedance interconnection of all inactive metal parts.

SFor screw connections on painted and anodized metal parts, either use special contact washers or remove the insulating protective layers.

SIf possible, do not use aluminum parts. Aluminum oxidizes easily and is therefore less suitable for grounding.

SMake a central connection between the chassis ground and the ground/protective ground conductor system.

Ensure proper routing of lines when wiring (see Sections 3.3.1 and 3.3.2).

SArrange the cabling in line groups. (AC power cable, power supply lines, signal lines, data lines)

SAlways install AC power cables and signal or data lines in separate ducts or bunches.

SRoute the signal and data lines as closely as possible to grounded surfaces such as cabinet elements, metal bars and cabinet panels.

Ensure that cable shields are properly secured (see Section 3.3.3).

SData lines must be shielded. The shield should be connected at both ends.

SAnalog lines must be shielded. For the transfer of signals with low amplitudes, it may be advisable to connect the shield at only one end.

SProvide the line shields with a large-area connection to a shield/protective conductor bar immediately after the cabinet inlet, and secure the shields with cable clamps. Route the grounded shield as far as the module without interruption, but do not connect the shield there again.

SEnsure that the shield/protective ground bar has a low-impedance connection to the cabinet.

SUse metal or metallized connector cases for shielded data lines.

3-6	System Manual
	C79000-G8576-C199-06