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KESS Power Solutions Gmbh / www.kess.at / info@kess.at
As safety measure it is necessary to connect the auxiliary contact of the bypass
and teh UPS, including the loads, to the powerboard with same functionality. This
prevents that an incorrect action at the manual bypass disconnector leads to a
total or partial failure of the device. The same is applicable for systems in parallel.
fig.13: Auxiliary contact for the external bypass with synchronization
6.13 PARALLEL CoNNECTioN (oNLy foR ModELS > 3 KVA)
N+x is usually the most reliable power structure. N represents the minimum
number of devices that the total load needs. x represents the number of
redundant devices, that means the number of faulty UPS devices which are allowed
simultaneously by the system. The higher x is, the greater the reliability of the
system is. for occasions where reliability is very essential, N+x will be the optimum
mode.
Up to 3 devices can be connected in parallel to confi gure a shared output or
power redundancy.
Parallel installation and operation:
The communication line - com - constitutes a very low voltage safety circuit. To
preserve the quality, this line must be installed separately from other lines carrying
dangerous voltages (power distribution lines).
Bus for parallel connections and current signal bus:
Use the 15-wire signal cable with mesh and db15 connectors at the ends to
connect a maximum of 3 devices. Each cable has a male and a female
connector at the ends which must be connected to link two devices. it is
essential to close the communications loop of the parallel bus and the current
signal bus through the cable with the connectors (see fig. 14). The length of
the cables related to the parallel bus is approximately 1,5 metres and must
not be prolonged under any circumstances due to the risk of interference and
communication failures that could be the consequences.
Communication bus
Current signal bus
fig.14: Communication and current signal connections for a parallel system