Grounding the System

Introduction

Use shielded, properly grounded cables for all analog and high-speed inputs or outputs and communication connections. If you do not use shielded cable for these connections, electromagnetic interference can cause signal degradation. Degraded signals can cause the controller or attached modules and equipment to perform in an unintended manner.

Warning_Color.gifWARNING

UNINTENDED EQUIPMENT OPERATION

oUse shielded cables for all fast I/O, analog I/O and communication signals.

oGround cable shields for all analog I/O, fast I/O and communication signals at a single point1.

oRoute communication and I/O cables separately from power cables.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

1Multipoint grounding is permissible if connections are made to an equipotential ground plane dimensioned to help avoid cable shield damage in the event of power system short-circuit currents.

The   use of shielded cables requires compliance with the following wiring rules:

oFor protective ground connections (PE), metal conduit or ducting can be used for part of the shielding length, provided there is no break in the continuity of the ground connections. For functional ground (FE), the shielding is intended to attenuate electromagnetic interference and the shielding must be continuous for the length of the cable. If the purpose is both functional and protective, as is often the case for communication cables, the cable should have continuous shielding.

oWherever possible, keep cables carrying one type of signal separate from the cables carrying other types of signals or power.

The figure below represents a TM5 System with shielded cables:

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1   Protective ground (PE)

2   Functional ground (FE)

Protective Ground (PE) on the Backplane

The protective ground (PE) is connected to the conductive backplane by a heavy-duty wire, usually a braided copper cable with a cross-section of 6 mm2 (AWG 10) or larger.

Functional Ground (FE) on the DIN Rail

The DIN Rail for your TM5 System is common with the functional ground (FE) plane and must be mounted on a conductive backplane.

Warning_Color.gifWARNING

UNINTENDED EQUIPMENT OPERATION

Connect the DIN rail to the functional ground (FE) of your installation.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

The connection between the functional ground (FE) and your TM5 System is made by the DIN Rail contacts on the back of the controller and the bus base of the expansion modules.

Shielded Cables Connections

Cables carrying the fast I/O, analog I/O, network and field bus communication signals must be shielded. The shielding must be securely connected to ground. The fast I/O and analog I/O shields may be connected either to the functional ground (FE) of your system via the TM2XMTGB grounding plate or to the protective ground (PE). The field bus communication cable shields must be connected to the protective ground (PE) with a connecting clamp secured to the conductive backplane of your installation.

Danger_Color.gifDANGER

HAZARD OF ELECTRIC SHOCK

Make sure that CANopen and Modbus cables are securely connected to the protective ground (PE).

Failure to follow these instructions will result in death or serious injury.

Warning_Color.gifWARNING

ACCIDENTAL DISCONNECTION FROM PROTECTIVE GROUND (PE)

oDo not use the TM2XMTGB Grounding Plate to provide a protective ground (PE).

oUse the TM2XMTGB Grounding Plate only to provide a functional ground (FE).

Failure to follow these instructions can result in death, serious injury, or equipment damage.

NOTE: The functional ground of the Ethernet connection is internal.

The shielding of the following cables must be connected to the protective ground (PE):

oCANopen

oModbus

Functional Ground (FE) Cable Shielding

Step

Description

1

Install the Grounding Plate directly on the conductive backplane below the TM5 System as illustrated.

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2

Strip the shielding for a length of 15 mm (0.59 in.)

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3

Tightly clamp on the blade connector (1) using nylon fastener (2)(width 2.5...3 mm (0.1...0.12 in.)) and appropriate tool.

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Protective Ground (PE) Cable Shielding

Step

Description

1

Strip the shielding for a length of 15 mm (0.59 in.)

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2

Attach the cable to the conductive backplane plate by attaching the grounding clamp to the stripped part of the shielding as close as possible to the TM5 System base.

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NOTE: The shielding must be clamped securely to the conductive backplane to help ensure good contact.