SMA WB 3000-21 Installation - Manual (Page 30)

6 Electrical Connection SMA Solar Technology AG
30 WB3-5TL-21-IA-en-10 Installation Manual
☐ The cable must be dimensioned in accordance with the local and national directives for the
dimensioning of cables. The requirements for the minimum wire size derive from these directives.
Influencing factors for cable dimensioning are, among others, the following: nominal AC
current, type of cable, routing method, cable bundling, ambient temperature, and maximum
desired line losses.
Switch-disconnector and cable protection:
• In plants with multiple inverters, protect every inverter with a separate miniature circuit-breaker.
Observe the maximum permissible fuse protection (see Section 13 "Technical Data", page 77).
That prevents residual voltage being present at the corresponding cable after disconnection.
• Loads installed between the inverter and the miniature circuit-breaker must be protected
separately.
Residual-current device:
• If an external residual-current device is prescribed, install a residual-current device that trips at
a residual current of 100 mA or higher (for information on choice of residual-current devices,
see the Technical Information "Criteria for Selecting a Residual-Current Device" at
www.SMA-Solar.com).
Protective conductor monitoring:
The inverter is equipped with protective conductor monitoring that detects if the protective conductor
is not connected and if this is the case, disconnects the inverter from the power distribution grid.
Depending on the installation site and grounding system, it may be advisable to deactivate the
protective conductor monitoring. Ask your grid operator or SMA Solar Technology AG to advise.
• To ensure safety according to IEC 62109 when the protective conductor monitoring is
deactivated, connect a protective conductor to the connecting terminal plate for the AC cable
(minimum cross-section: 10 mm², copper wire).
or
Connect a second protective conductor with the same wire size as the original protective
conductor (see Section 6.3.3 "Additional Grounding of the Enclosure", page 34). This prevents
touch current if the original protective conductor fails.
Damage to the inverter due to the use of screw-type fuses as load disconnection units
Screw-type fuses (e.g. DIAZED fuses or NEOZED fuses) are not switch-disconnectors
• Do not use screw-type fuses as load disconnection units.
• Use a switch-disconnector or miniature circuit-breaker as a load disconnection unit
(for information and examples for designing, see the Technical Information "Miniature
Circuit-Breaker" at www.SMA-Solar.com).
Connection of a second protective conductor
In some countries a second protective conductor is required as a matter of principle.
In each case, observe the local applicable regulations.