Delta AU Series - AC Circuit Breaker Requirements; Grounding Conductor; Lightning and Surge Protection; Multiple Inverters

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4.4 AC circuit breaker requirements
A dedicated circuit breaker in the building circuit panel is required for each Delta M series inverter
that is installed. There should be a circuit breaker or fuse to protect each AC line, L and N. The
circuit breaker should be able to handle the rated maximum output voltage and current of the
inverter. Please refer to the table below to determine the appropriate circuit breaker size to avoid
potential fire hazards. The SAI Global AS/NZS 5033 or applicable local electrical codes must be
followed when determining maximum branch-circuit over-current protection requirements.
Inverter model Recommended AC branch protection
M3-TL 2-pole, 20 A 230 Vac
M4 -TL 2-pole, 25 A 230 Vac
M5 -TL 2-pole, 30 A 230 Vac
Please note that there is an exception to the requirement of a dedicated circuit breaker in the buil-
ding circuit panel for each inverter if there exists a dedicated PV system AC subpanel that is used
to combine multiple inverters. In this case, only one breaker at the main building service panel
should be installed for a multiple inverter installation utilizing a dedicated PV system AC subpanel.
4.5 Grounding conductor
Per AS/NZS 5033, a grounding conductor must be installed, and the PE conductor must be sized
in accordance with AS/NZS 3000. The grounding conductor should be terminated at the PE screw
terminal inside the wiring box compartment. Grounding wire shall be selected based on the local
rules and its diameter is no less than 4 mm
2
. Green, yellow double color line is recommended for
protective grounding and secondary grounding terminal at the bottom of inverter shall be reliable
grounded as well as the grounding inside AC terminal, or personal injury may be caused.
4.6 Lightning and surge protection
Delta M series AU inverters are designed and certified to meet stringent AS/NZS 4777 and IEC
62109-2 AC lighting and surge requirements; however, every PV installation is unique, thus
additional external AS/NZS AC and DC surge protection and solid grounding practice is
recommended
4.7 Multiple inverters
Multiple Delta M series inverters are permitted at a common location if all applicable SAI global,
local building codes and local utility commissioning guidelines are met. In addition, each inverter
should have its own dedicated AC branch protection circuit breaker and a dedicated PV string/
array, not to exceed the inverter’s ratings.