0MNA080A55-GB REV 01 page 37 / 75
4.2.4 External maintenance by-pass.
In some cases, in order to facilitate maintenance operations of the individual units making up the system, it may be
advisable to install an external maintenance by-pass.
This device, which is housed in a cabinet the same height as the UPS, consists of two disconnectors, one for the
output and one for the by-pass; these are sized for the total power of the system.
The new disconnector located on the by-pass line (S) must be provided with auxiliary contacts (one for each UPS).
The position of the contact is opposite to the position of the switch, thus the contact must be closed when the
disconnector is open.
The contacts of each disconnector must be connected to the corresponding UPS terminals, as shown in the diagram.
da S
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