Danfoss VLT HVAC Drive FC 102 Operating Manual page 43

Operating Guide | VLT® HVAC Drive FC 102
Also, remember to practice the following:
• When using relays, control cables, a signal interface, fieldbus, or brake, connect the shield to the enclosure at both ends. If the
ground path has high impedance, is noisy, or is carrying current, break the shield connection on 1 end to avoid ground current
loops.
• Convey the currents back to the unit using a metal mounting plate. Ensure good electrical contact from the mounting plate by
securely fastening the mounting screws to the drive chassis.
• Use shielded cables for motor output cables. An alternative is unshielded motor cables within metal conduit.
• Ensure that motor and brake cables are as short as possible to reduce the interference level from the entire system.
• Avoid placing cables with a sensitive signal level alongside motor and brake cables.
• For communication and command/control lines, follow the particular communication protocol standards. For example, USB must
use shielded cables, but RS485/ethernet can use shielded UTP or unshielded UTP cables.
• Ensure that all control terminal connections are rated protective extra low voltage (PELV).
TWISTED SHIELD ENDS (PIGTAILS)
Twisted shield ends increase the shield impedance at higher frequencies, which reduces the shield effect and increases the
leakage current.
Use integrated shield clamps instead of twisted shield ends.
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SHIELDED CABLES
If shielded cables or metal conduits are not used, the unit and the installation do not meet regulatory limits on radio frequency
(RF) emission levels.
EMC INTERFERENCE
Failure to isolate power, motor, and control cables can result in unintended behavior or reduced performance.
Use shielded cables for motor and control wiring.
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Provide a minimum 200 mm (7.9 in) separation between mains input, motor cables, and control cables.
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INSTALLATION AT HIGH ALTITUDE
There is a risk for overvoltage. Isolation between components and critical parts could be insufficient, and may not comply with
PELV requirements.
Use external protective devices or galvanic isolation. For installations above 2000 m (6500 ft) altitude, contact Danfoss
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regarding protective extra low voltage (PELV) compliance.
PROTECTIVE EXTRA LOW VOLTAGE (PELV) COMPLIANCE
Prevent electric shock by using PELV electrical supply and complying with local and national PELV regulations.
Danfoss A/S © 2018.10
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Electrical Installation
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