breakers must be selected according to the maximum short-circuit current
(max Isc) that is needed to determine the breaking power of automatic circuit
breakers, and to the minimum current (min Isc) that is needed to determine the
maximum length of the line protected. The protection against short-circuit must
operate on the line before any thermal and electro-thermal effects of the
over-current may damage the cable and relevant connections.
During the electrical installation take particular care to respect the phase
UPS up to 20 kVA
The terminal boards are placed on the rear of the UPS, under the breakers.
To access the terminals remove the protection, remove the fixing bolts.
UPS 30 – 40 kVA
The terminal boards are placed on the front of the UPS. To access the
terminals remove the front panel, remove the fixing bolts.
The connection to the mains must be carried out with protection fuses between
the mains and the UPS.
The use of differential protection devices in the line supplying the UPS is
unadvisable. The leakage current to ground due to the RFI filters is rather
high and it can cause spurious tripping of the protection device.
According to IEC EN62040-1 standard, in order to take into account the UPS'
leakage current, residual current devices having adjustable threshold can be
Include an appropriate and readly accessible disconnect device in the
fixing wire connecting the UPS to the mains.