Hoyer HMA2, Руководство пользователя

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31
Motor
Manual
garding high frequency currents .
• Effectiveness of protection to enhance electromagnetic
compatibility (EMC)
• EMC screened equipment suitable for VFD opera-
tion is recommended and could, among others,
include:
•
Sufficient cable screening, cable gland connec-
tions, suitable high frequency earthing etc .
To reduce the risk of bearing currents and corresponding
downtime of the motor application, please see the sugges-
tions for motor applications operated with VFD’s in the
section 8 .5 Hoyer VFD application suggestions .
8 .4 Additional solutions for limitation of bear-
ing currents
In special cases where bearing current still occurs, or for
essential applications where optimised uptime is signifi-
cant, additional actions may be recommended . Depending
on application and installation requirements, the follow-
ing advanced solution will ensure a high reliability:
•
Grounding brushes can be mounted to ensure a good
earthing connection between motor housing and shaft .
• Insulated bearing in NDE and DE
• Hybrid bearing with ceramic balls in NDE or DE .
• Combination of Hybrid bearing in NDE and brush in DE
Grounding brushes are installed outside the motor hous-
ing and makes the connection from stator to shaft . Brush-
es must periodically be inspected for wear and tear in or-
der to ensure an optimized protection .
With insulated bearings mounted in drive-end and none-
drive-end, the shaft is electrically insulated from the sta-
tor, meaning that no bearing current will run from stator
to rotor . Bearings with ceramic balls are recommended as
the most reliable solution .
Be aware of any bearings in the application, so that the
bearing current does not pass through these when the mo-
tor bearings are insulated and a grounding brush is not
used .
8 .5 Hoyer VFD application suggestions
To ensure a reliable VFD- and motor operation, please
take the suggestions listed in below table into account .
In general Hoyer recommends reenforced insolation sys-
tems and insulated bearings in NDE when the motor has
a power-size above 75 kW or a supply voltage above 500 V .
Common mode filters are recommended above 75 kW and
dU/dt filters should be implemented when supply voltages
surpasses 500 V . Hoyer can deliver all types of filters upon
request .
Supply
voltage
Power
Winding
insula-
tion
Motor
bearings
Drive
filters*
< 500 V
< 75 kW
Hoyer
standard
insulation
Standard
bearings
No filter
needed
≥
75 kW
Hoyer
standard
insulation
Insulated
non-drive
end bear-
ing
Common
mode filter
≥
500 V
<75 kW
Hoyer
reinforced
insulation
Standard
bearings
dU/dt filter
≥ 75 kW
Insulated
non-drive
end bear-
ing
dU/dt filter
& common
mode filter
*Common mode filters can generally be recommended in all mo-
tor sizes
Hoyer premium reinforced insulation system can be implemented
upon request
Table 14: Hoyer motor recommendations to bearing current and
filter mitigation with VFD control.