Eurotherm 590+ Series, Product Manual, Page: 56 / 308

3-30
Installing the Converter
590+ Series DC Digital Converter
other end to the cubicle back panel. Ideally 360
o
bonding is required, which can be achieved
with cable glands, refer to Figure 3-5 360 Degree Screened Connection, page 3-6.
„
Ensuring that conduit containing the motor supply cables are bonded together using braid.
The conduit should also be bonded to the motor frame and the cubicle back panel.
Earthing Details
The protective earth (PE) conductor exiting the filter must be connected to the protective earth
connection of the Converter. Any additional RF earth, such as a cable screen,
is not a protective
earth . The EMC filter must be permanently earthed to prevent the risk of electric shock under
abnormal operating instances (such as the loss of one phase of the ac supply).
You can achieve permanent earthing by either:
•
using a copper protective earth conductor of at least 10mm²
•
installing a second conductor, in parallel connection with the protective conductor, to a
separate protective earth terminal
Each conductor must independently meet the requirements for a protective earth conductor.
Operating Conditions
The recommended EMC filters operate from normal three-phases supplies which are balanced
with respect to earth (earth referenced supplies - TN). This minimises the earth leakage current
due to the filter capacitors between phase and earth.
IMPORTANT: We do not recommend the use of ac supply filters on non earth-referenced supplies - IT.
The supplies cause earth leakage currents to increase, and interfere with the operation of
earth fault monitoring equipment. In addition, EMC performance of the filter is degraded.
As with all power electronic drives, conducted emissions increase with motor cable length. EMC
conformance is only guaranteed up to a cable length of 50m. The cable length can be increased.
Refer to Eurotherm Drives for more information.
Earth Fault Monitoring Systems
WARNING!
Circuit breakers used with VSDs and other similar equipment are not suitable for
personnel protection. Use another means to provide personal safety. Refer to
EN50178 (1998) / VDE0160 (1994) / EN60204-1 (1994)
We do not recommend the use of circuit breakers (e.g. RCD, ELCB, GFCI), but where their use
is mandatory, they should:
• Operate correctly with dc and ac protective earth currents (i.e. type B RCDs as in
Amendment 2 of IEC755).
•
Have adjustable trip amplitude and time characteristics to prevent nuisance tripping on
switch-on.
Note: When the ac supply is switched on, a pulse of current flows to earth to charge the EMC
filter internal capacitors which are connected between phase and earth. This has been
minimised in Eurotherm Drives filters, but may still trip out any circuit breaker in the earth
system. In addition, high frequency and dc components of earth leakage currents will flow
under normal operating conditions. Under certain fault conditions larger dc protective
earth currents may flow. The protective function of some circuit breakers cannot be
guaranteed under such operating conditions.