SAMLEX AMERICA INC. | 53
SECTION 3 |
Installation
3.12 GROUNDING ARRANGEMENT
Internally, EVO™ consists of DC and AC Section that are isolated through a transformer
(See Transformer T-1 in Fig 3.13)
.
Both these sections are required to be grounded appropriately.
For wiring details for appropriate grounding, refer to Fig 3.13, and associated explanation under Sections 3.13 and 3.14.
When using a generator instead of Grid, please ensure that the Neutral of the generator is bonded to the metal frame
of the generator and the metal frame of the generator is bonded to Earth Ground through the Grounding Electrode
(GE) i.e. the Ground Rod. Refer to Section 3.14.1 for additional details.
3.13 DC SIDE GROUNDING
Please refer to Fig 3.13.
DC side grounding involves bonding of the metal frame/chassis of EVO™, the metal chassis of the DC Electrical Panel
and the Battery Negative Terminal to Earth Ground in shore based installation (
Fig 3.13
). This ensures that in case of
a ground fault in the +48V circuit, the fuse in the +Battery line blows to clear the fault. This fuse in the +Battery line
has Ampere capacity matching the rated DC input current of the EVO™ in Inverter Mode. The wire size used for DC
side grounding should be minimum AWG #6 or of the same size as the battery cable, whichever is thicker (
Battery
cable size should have minimum Ampacity ≥ the Ampere rating of this battery fuse depending upon the model of the
EVO™ being used
).
This recommendation on sizing of the DC Side Grounding Wire will be superseded by the
National / Local Electrical Codes.
i
INFO
As described at Section 3.14, the metal frame / chassis of the EVO™
(Fig 3.13)
is bonded to the Grounding
Electrode "GE" (
Ground Rod
) for AC side grounding. It may be argued that if the metal frame / chassis of
EVO™ is already bonded to the Grounding Electrode "GE" for AC side grounding, why is it necessary to provide
additional DC side grounding wiring? (
Wiring that bonds DC Grounding Terminals "5", "G-B" and GE in Fig
3.13)
. If separate thicker grounding wire of the same size as the battery cable was not provided for the DC side
grounding and there was a ground fault in the battery circuit, very large DC fault current from would
flow through the smaller size AC grounding wires to the Battery Negative through Earth Ground. These smaller
size AC side grounding wires would be damaged due to very high DC side fault current
(few hundred Amperes)
.
A DC Side Grounding Connector
(Figs 2.1 and 3.8)
is provided for connecting to the System Ground. The connector
can accept wire sizes AWG # 4–6. The set screw size is M6.
A DC Electrical Panel, as shown in Fig 3.13, is often used to connect the batteries and distribute DC power to the
inverter and to the other DC loads.
The Negative of the battery is connected to the Neg (-) Bus of the DC Electrical Panel which, in turn, is connected to
its Grounded Bus Bar (G-B). Grounded Bus Bar (G-B) of the DC Electrical Panel is further bonded to the Grounded Bus
Bar (G-B) of the Grid Electrical Panel and then to the Grounding Electrode (GE), also called Ground Rod. Hence, the
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