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Hipulse - Single Phase ‘1+N’ UPS System 130 kVA - 110V
15
WARNING
Failure to follow adequate earthing procedures can result in electric
shock hazard to personnel, or the risk of fire, should an earth fault
occur.
3.1.6 Protective devices
For safety reasons, it is necessary to install, external to the UPS, circuit breaking
protective devices in the input a.c. supply and towards the battery. Given that every
installation has its own characteristics, this chapter provides general useful
information engineers, with knowledge of operating practices, of regulatory standards,
and of the equipment to be installed.
Rectifier and bypass inputs:
Protection against excessive over currents and short circuits
These inputs must be protected, installing suitable protective devices at the
distribution panel of the incoming main supply, considering that the protection should
discriminate with overload capacity of the system (see Chapter 9: Specification -
Electrical Characteristics).
Split Bypass :
In the case of a split bypass being used, separate protective devices should be
installed in the incoming mains distribution panel.
The protective devices must be selected for the nominal input current, with respect to
the UPS rating and the input a.c. supply voltage as given in table 3-1.
Protection against earth faults (RCD devices):
In the event of a differential (RCD) device being installed upstream of the input supply,
one must take into account transient and steady state earth leakage currents that are
produced during start-up of the UPS.
The presence of an RFI suppression filter inside the UPS, determines a residual earth
current greater than 3.5mA and less than 1000mA.
Residual current circuit breakers (RCCB) must be sensitive to d.c. unidirectional pulse
(class A) in the network and insensitive to transient current pulses.
They are identified by the symbols respectively.
These isolators must have an average sensitivity, possible adjustable between 0.3 and
1A.
It is recommended that the selectivity with every differential switch be verified both
upstream of the input distribution board and downstream (towards the load).