Brochure/Catalogue

To summarise: protective circuitry with absolutely zero
leakage current is in place and an accidental activation of
the disconnecting mechanism is prevented. In the scenario
described above, the spread of re is also effectively
prevented. And at the same time, any inuence from
an insulation monitoring device is also avoided. So if an
insulation malfunction occurs, there are always two varistors
still available in the series. In this way, the requirement that
earth faults must always be prevented, is met. Weidmüller‘s
SPD type 2 arrester VPU II 3 1,000 V DC to UCPV mode +/–,
–/PE, +/PE = 1,000 V DC provides a well tested, practical
solution and has been tested for compliance with all current
standards (UTE C 61-740-51 and EN 50539-11) (Figure 4).
In this way, we offer the highest degree of safety available
for use in DC circuits.
Practical applications
As already stated, a difference is drawn between building
and eld installations in practical solutions. If an external
lightning protection solution is tted, the PV generator
should preferably be integrated into this system as an
isolated arrester device system. IEC 62305-3 species that
the air termination distance must be maintained. If it cannot
be maintained then the effects of partial lightning currents
must be taken into consideration.
On this point the standard for protection against lightning
IEC 62305-3 Supplement 2 states in Section 17.3: ‘to
reduce induced overvoltages shielded cables should be
used for the main lines of the generator’. If the cross-
section is sufcient (min. 16 mm² Cu) the cable shielding
can also be used to conduct partial lightning currents.
Supplement (Figure 5) - Protection against lightning for
photovoltaic systems – issued by the ABB (Committee for
Lightning Protection and Lightning Research of the (German)
Association for Electrical, Electronic and Information
Technologies) states that the main lines for the generators
should be shielded. This means that lightning current
arresters (SPD type 1) are not required, although surge
voltage arresters (SPD type 2) are necessary on both sides.
As Figure 5 illustrates, a shielded main generator line offers
a practical solution and achieves LPZ 1 status in the process.
In this manner, SPD type 2 surge arresters are deployed in
compliance with standards specications.
Photovoltaic application example
Converter
Solar Panel
DC
AC
Insulationfault toward PE
U
oc
< 1000 Vc
MOV = Metall Oxyd Varistor
U U
U
MOVMOV
MOV
Figure 4: Y-shaped protective circuitry with three varistors
Figure 5: Building installation with external lightning protection,
not in compliance with air termination distances
F
Surge protection for photovoltaic systems
F.6 2028840000