48
6.5 Backfeed Protection
To support protection against UPS backfeeding a new logic is integrated
into tower 3/1 10k-20k model. But in tower 3/1 10K-31C model
，
there’s
no this function.
Using backfeed protection
On customers side an additional external isolation device (magnetic
contactor, MC or minimum voltage tripping device) must be provided as
shown in Fig. 6-3. The isolation device must be able to carry the UPS
input current (see resp. table of basic UPS operating instructions).
The isolation device has to be installed in the bypass source path.
Cabling of the backfeed terminals contains a jumper and two cables to
the optional external isolation device.
49
T
er
mi
na
ls
Ma
in
s
T.
B
Ba
ck
fe
ed
T
.B
Fig. 6-4 Tower 3/1 10-20k and external isolation device
(in this example a magnetic contactor (MC))
Fig. 6-5 Backfeed terminal
