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1.5.8 High Voltage Connections
Always note inverter voltage, select appropriate over current protection devices,
select disconnect device, and select proper wire size before beginning the wiring
process. Wire the drive according to NFPA 70 Class 1 requirements.
The correct wire gauge for each size inverter can be selected from the charts
under Section 2.1-2.2 . The wire gauge is based on the maximum fuse rating for
the inverter. The terminal tightening torque can be found for each unit in the same
charts.
Always use UL listed and CSA approved wire. Use 60/75°C copper conductors
only for equipment rated 100 Amperes or less and use 75°C Copper Conductors
only for equipment rated grater than 100 Amperes! Use minimum 300V rated wire
with 230V systems and minimum 600V rated wire with 480V systems.
To prevent coupling high frequency noise, the following wires must be spatially
separated from each other a minimum distance of 8 inches (20 cm) when they
are laid parallel to each other :
- AC supply power and motor lines not connected to inverters
- motor lines connected to inverters
- control and data lines ( low-voltage level < 48 V )
When using EMI î lters, use only the wire provided with the î lter to connect the
î lter to the inverter. Do not add additional wire between the î lter and the inverter
as this will have a negative effect on the operation of the î lter.
1.5.9 Ground Connections
When working with high frequencies ( > 1kHz ) and power semiconductors it is
recommended to make all ground connections with large exposed metal surfaces
in order to minimize the ground resistance.
The metal sub-plate the inverter is mounted on is regarded as the central ground
point for the machine or the equipment. For best results use an unpainted,
galvanized or plated sub-panel.
An additional high frequency ground wire should be connected between the
inverter and the sub-panel. Use a stranded wire equal in size to the main line
conductor or a thick ground strap. This is in addition to the ground wire required
by NFPA 70, UL 508, CSA 22.1
All ground connections should be kept as short as possible and as close as
possible to the ground system, sub-panels.
If other components in the system exhibit problems due to high frequency
disturbances, connect an additional high frequency ground wire between them
and the sub-panel.
The EMI î lter should be mounted to the drive or as close as possible to the
inverter and on the same sub-panel as the inverter. Good metallic surface contact
to the sub-panel is required to provide adequate high frequency grounding of the
î lter.
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