Critical Power
Modifications reserved
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GE_UPS_ISG_TLE_SUL_M16_M50_2bU_V010.docx
Installation Guide
TLE Series 160 - 500 UL S2B
4.7.2
Input/output over current protection and wire sizing
The cabling of the UPS system has to be sized according to the UPS power rating.
Sizing of circuit
Breakers
,
Fuses
and
cables
for
Input Utility
,
output load
and
Battery
must meet the
requirements of local and national electrical codes.
Before connecting the UPS, verify that the
Utility Voltage
and
Frequency
, the O
utput Load Voltage
and
Frequency
and
Battery Data
(cells number, floating voltage, autonomy) are according to the required
data.
The protection of the UPS utility input must be exclusively with 3 pole breakers.
In 4-wire distributions (3-phase, 4-wire plus ground):
•
Disconnection of the Neutral is not permitted.
The UPS needs the connection of the
Neutral
to the input, to guarantee the function in
TN mode
(Neutral-Earth).
•
Caution when using
Four-Pole Circuit Breakers
as protection to the UPS Load.
A potential problem exists for situations with non-linear Loads, causing the Neutral Current to be
higher than the Phase Current.
Avoid to run the
input cables
in parallel with the
output cables
to prevent them from noise induction.
The
Three-Phase Utility Power
supply must be symmetrical with respect to
Ground
(wye-connected and
grounded solidly), due to the existence of voltage surge protection devices inside the UPS.
The connection of the
Battery
to the UPS must be protected with
fuses
or similar devices according to
technical specifications and in accordance with local standards.
NOTE !
If you use ELCB breaker (Earth Limiting Circuit Breaker) to protect the input
connections, consider the high leakage current generated by the noise suppression
capacitors.
If these ELCB breakers are strictly necessary, we suggest using the largest type
suitable for non-linear current and for delayed operations.
Specific prescriptions apply for 3-wire (3-phase plus ground) distributions; refer to
the specific section for details.
To ensure the circuit selectivity in case of
Short- Circuit in the Load equipment
, special care must be
taken in choosing the
Fuse or Circuit Breaker ratings
installed in the output distribution circuits.
Due to the relatively low short-circuit capability of the
UPS Inverter
, a short-circuit in the
Load
will cause
an immediate transfer to
Utility
.
The
largest fuse
in the output distribution should be
at least 1.6 time
smaller than the
Fuses
supplying
the
Bypass line
.
If circuit selectivity is required while the
Load
is fed from the
Inverter
(Bypass Utility
not available), the
Largest Fuse
or
Circuit Breaker
should be rated at no more than
20%
of the
UPS Output Current Rating
.
NOTE !
The delivery and installation of fuses and input/output connections of the UPS are at
the customer’s expense, unless agreed otherwise.
