User Manual
Chapter 3 - Installation Procedure
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3.3.5 Protective
devices
For safety reasons, it is necessary to install external to the Network Power Switch system, circuit breaking protective
devices in the input a.c. supply and towards the output. Given that every installation has its own characteristics, this
chapter provides general useful information for qualified installation engineers, with knowledge of operating practices,
of regulatory standards, and of the equipment to be installed.
Rectifier and Bypass input supply of the Network Power Switch:
The input to Network Power Switch should be given through a 32 amp, 2pole ELCB for safe operation.
Protection against excessive overcurrents and short circuits in the mains supply input:
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.
The protective devices must be selected for the nominal input current, with respect to the rating and the input a.c.
supply voltage as given in table 3-1.
Protection against earth faults (RCD or RCCB devices):
In the event of a differential (RCD) device being installed upstream of the input supply, one must take into account the
transient and steady state earth leakage currents that are produced during start-up of the Network Power Switch.
The presence of an RFI suppression filter inside the NPS, determines a residual earth current not greater than 3.5 mA.
Residual current circuit breakers (RCCB/RCD) must be sensitive to d.c. unidirectional pulses (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, possibly adjustable between 10mA and 0,3A.
It is recommended that the selectivity with every differential switch be verified both upstream of the input distribution
board and downstream (towards the load).
Output of the System:
In the eventuality that an external distribution panel is used for load distribution, the selection of protective device must
provide discrimination with those that are used at the input to the Network Power Switch module.
3.3.6 Cabling
Procedure
The external power cables should be connected to the terminals as shown in figure 5.1.2 in Chapter 5. Proper
termination labels are provided near each connector for ease of cabling.
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