67Installation
EN
5.6.2 Load protection breaker (AC disconnect switch)
To protect the AC connection line of the inverter, an overcurrent protection device with the following
features must be installed (these are the caracteristic of a load protection switch referred to a single
inverter installation):
Load protection breaker requirements
Type
Automatic circuit breaker with
thermal-magnetic protection
Fuses switch disconnector
Voltage/current rating
800 V / 150 A (*) 800 V / 200 A (*)
Magnetic protection
characteristic
Magnetic curve B/C gG, gS
Number of poles
3 3
(*): please consider thermal and other derating when selecting the current rating of the protection equipment for your application.
5.6.3 differential protection downstream of the inverter
All ABB string inverters commercialized in Europe are equipped with a device for protection against
ground faults in accordance with the safety standard IEC 62109-2 (please refer to sections 4.8.2 and 4.8.3
of the Standard). In particular, ABB inverters are equipped with a reading redundance for the ground
leakage current sensitive to all components of both direct and alternating current. Infact the measurement
of the ground leakage current is carried out simultaneously and independently by 2 different processors:
it is sufficient for one of the two to detect an anomaly to trip the protection, with consequent disconnection
from the grid and to stop the conversion process.
There is an absolute threshold of 1.6 A for the overall leakage current AC+DC with protection tripping time
at a max. of 300 msec.
Furthermore, there are other three tripping levels with limit set respectively at 30 mA, 60 mA and 150 mA
to cover the “rapid” changes in fault current induced by accidental contact with leaking live parts. The
max. tripping times are progressively shortened as the speed of change in the fault current increases and,
starting from the 300 msec/max for the 30 mA change, they are reduced respectively to 150 msec and 40
msec for 60 mA and 150 mA changes.
In case of installation of a residual current protection device, this shall meet the following characteristics
in order to prevent nuisance tripping due to capacitive leakage current of photovoltaic modules:
Residual current protection device requirements
Type
A / AC
Sensitivity
2.0 A
NOTE – D For protection of the AC line, on the basis of the information above with regard to the
differential protection integrated in ABB inverters, it is not necessary to install a type B ground
fault switch.
NOTE – D In accordance with article 712.413.1.1.1.2 of Section 712 of IEC Standard 64-8/7, we
hereby declare that, because of their construction, ABB inverters do not inject ground fault
direct currents.
NOTE – D In the case of systems which consist of several inverters connected to a single switch
with differential protection, it is recommended to install a device which allows the adjustment
of the tripping value and the tripping time.
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