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Siemens Building Technologies Commissioning Guide CM1G5192en
HVAC Products 4 EMC-compatible installation of SED2 26.02.2003
4.4 EMC-compatible wiring
• Use only shielded cables for the motor. The shielding should have the lowest possible HF impedance and
must be continuous
• Use only shielded cables for the signal, control and data lines (shielded twisted pair)
• The HF transfer resistance at the connecting points between shielding and housing should be kept as low as
possible
• Connect the shielding of motor and control cables to ground at both ends. For that purpose, use EMC cable
fittings (EMC fittings, EMC cable clamps, EMC terminals and similar that ensure 360° contact of shielding)
• Avoid high equalization currents on the shielding by ensuring a low-resistance (min. 16 mm
2
copper) and low-
impedance connection between VSD housing and ground (potential equalization rail)
• Connect the neutral conductor of the motor controlled by the VSD directly to the earth connection (PE) of the
associated VSD
• Avoid cable loops
• Supply power to all devices in a starlike pattern
4.4.1 Potential equalization and earthing
• Connect all electrical components separately (starlike) to potential equalization
• With the IP54 versions, connect the housing – and with the IP20 versions the earthing terminal – of each
VSD to central ground (earthing or potential equalization rail) using a short, low-resistance potential equaliza-
tion line of low impedance
• For potential equalization lines, use flat, ribbon type conductors,
tin-plated copper mesh or similar (cross-sectional area at least
16 mm
2
) as they have a lower impedance at high frequencies
• Connect each motor controlled by the VSD to the ground or earthing point of the monoblock, also using a po-
tential equalization line having a large cross-sectional area (refer to illustrations on page 10 and 11).
• Ensure that each piece of control equipment (e.g. building management system or programmable logic con-
troller) connected to the VSD is connected to the same ground or same earthing point as the VSD using a short
potential equalization line (potential equalization rail)
• Connect movable parts (e.g. control cabinet doors or
hinged frames) via flexible grounding mesh
• Connect grounding to earth via protective conductors since, even in the event of fault, grounding may not carry
hazardeous voltage
• Avoid earth loops
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