Page 69 of 102
TVL 351
ISSUE 15
11.3. General EMC Guidelines
It is extremely important that the following guidelines are adhered to:
To maintain the high performance of this control system and its associated peripherals it is
essential you follow the Electro Magnetic Compatibility (EMC) and Safety instructions below.
Radio Frequency (RF) voltages and currents generated by the drive system can get into the
supply network by inductive and capacitive coupling. This causes unwanted radio frequency
interference signals that may damage this or other equipment.
Metal Work Earth Bonding
It is essential for maintaining EMC compliance that all parallel earthing conductors e.g. trunking/conduit & cable
trays etc. are bonded together using metal straps or braided cable. Standard control cable is not suitable, coiled
earth cables are ineffectual for bonding.
All metal work leading to and from the control cabinet, including the hoist motor, guide rails, shaft screening, guards,
covers, floor plates etc. must be electrically bonded together forming a continuous earth system. This is also
essential for health & safety reasons. Any metal enclosing electrical or electronic devices must be earthed.
High Voltage Cables
High voltage cables such as supply and motor cables should be run away from signal and low voltage cables,
preferable in separate trunking, typical separation distance to be of the order of 0.25 meters. If cables cross low
voltage cables, they should cross at right angles.
Where shown in the schematic diagrams, if a cable is screened it should be screened at both ends, braided cable is
best, armored cable may also be used. The screens must be terminated on the “W” clamps provided in the panel.
Pigtailed screens are inadequate for suppressing RF emissions and immunity, a 360 degree screen or saddle clamp
works best.
Incoming Supply Earthing
The main incoming supply must contain a suitably sized earth conductor that is terminated between the controller's
main earth point and the incoming mains isolator. Make sure the isolator and supply riser contain a good earth
conductor. The incoming supply must be screened and terminated correctly.
Main Hoist Motor Cable
The main motor cable is the worst cable in the system for emitting high levels of interference. It is essential that this
cable is run separately, screened and terminated. A suitably sized earth conductor must also be included in this
cable.
Motor Encoder Cables
The encoder screened cable should be run directly back to the controller without a break and routed away from
cables carrying drive controlled currents or cables carrying currents of an inductive nature. The encoder and its
screen must be isolated from the motor at the encoder end, if possible, and earthed at the appropriate terminal on
the controller.
Signal Wires - Segregation
All low voltage and signaling cables such as encoder cables, serial network cables, telephone lines & display cables
must be segregated from the following high emission cables: Hoist motor supply, brake supply, motor fan supply and
door gear supplies.
Signal Wires - Screening
Where shown on the schematics all signal and network wires must be run in shielded cable. Again, shield and
screens must be terminated correctly. Pigtailed screens are inadequate for suppressing RF emissions and immunity.
It cannot be stressed sufficiently that all variable frequency PWM inverters, by their nature of switching, emit EMI. It
is therefore essential that the aforementioned precautions are observed in order to reduce EMI to acceptable levels.
Equipment Immunity
The Ethos Two controller is designed to comply with current EMC regulation limits. Please be aware that the use of
high power radio transmitters over and above these limits, in the vicinity of the controller, may cause the processor
or other equipment to malfunction.
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