Modifications reserved
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OPM_SPE_XXX_10K_40K_8GB_V020.doc
Operating Manual
SitePro 10-15-20-30-40 kVA / S8
5.7.2 Input/output over current protection and wire sizing
NOTE !
The UPS is designed for TN System.
The input neutral shall be grounded at source and shall never be disconnected.
4 pole breaker shall not be used at the UPS input (see also IEC 60634, IEC 61140, IEC
61557).
The cabling of the UPS system has to be sized according to the UPS power rating.
Exceptions are only allowed to suit local prescriptions.
Sizing of circuit breakers, fuses and cables for input mains, output load and battery must meet the
requirements of local and national electrical codes.
Before connecting the UPS, verify that the
mains voltage
and
frequency
, the o
utput load voltage
and
f
requency
and
battery data
(cells number, floating voltage, autonomy) are according to the required
data.
The protection of the UPS mains input must be exclusively with 3 pole breakers.
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
then the phase current.
Avoid to run the input cables in parallel with the output cables to prevent them from noise induction.
The three-phase Mains power supply must be symmetrical with respect to earth, 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 breakers
to protect the input connections, consider the high leakage
current towards the earth generated by the noise suppression capacitors.
If these
ELCB breakers
are strictly necessary, we suggest to use the largest type
suitable for non-linear current and for delayed operation.
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 mains.
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 mains not available), the
largest fuse or circuit breaker should be rated at no more than
20%
of the UPS output current rating.
