Grounding - ABB OVR-15 Instruction, Operation And Maintenance Manual

18 O V R - 1 5 , 2 7 A N D 3 8 O U T D O O R VA C U U M R E C L O S E R H I G H VO LTA G E U N I T W I T H S E L7 5 1
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7.3 Grounding

12 Provisions for
grounding connections
on HV cabinet
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IMPORTANT
13 Grounding
connections proposed
Always follow international, national, local and
for OVR-15, 27, 38 pole-
mounted arrangement
company-specific regulations when grounding
the equipment.
All metal mounting frames and structures must be
commonly grounded to the grounding grid on the
installation site. Grounding is important to ensure
proper operation of all electronic components, as
well as to prevent penetration of EMC noise and
other transients into the sensitive electronic
circuits (SEL-751 relay, ACM, radios, etc.). Each
HV cabinet includes two stainless steel welded
grounding pads for grounding. Each pad has an
internal threaded hole (M8 for HV unit) as shown
in the figure below. 80 sq. mm cross-section, solid
copper strip/equivalent is recommended for
grounding.
If auxiliary power voltage transformer is used, it
should be grounded to the main ground conductor
leading from the recloser HV cabinet to ground. It is
mandatory that the HV cabinet is firmly grounded
as shown in this section when installed.
For the proper operation of electronic components,
the total impedance of the on-site grounding grid
must be less than one ohm (1 Ω).
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12
1. Surge arrestors not indicated on drawing must
be provided on incoming and outgoing medium
voltage terminals of the recloser.
2. All devices interfacing with the LV cabinet,
including HV cabinet (recloser), auxiliary power
transformer (PT), surge arrestors, etc., must
be connected to the same pole ground.
3. All connections of the LV cabinet must be routed
in close proximity to and parallel with their
corresponding ground paths for adequate
surge protection.
4. The LV control cabinet must be grounded
to its own pole ground.
5. The neutral of the secondary winding
of the auxiliary pole-mounted transformer
must be grounded at the transformer level.
6. The pole-grounding conductor must
be a continuous conductor.
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13
The grounding cables used must be the same
for all components.
Grounding pad