SMA SB 3300TL Installation - Manual (Page 16)

Requirements for the Installation SMA Technologie AG
Page 16 SB3300TL-11:SE2006 Installation Guide
Sizing of a circuit breaker for the AC line of a photovoltaic inver-
ter for utility interaction
Several factors have to be considered when you define the size of the circuit breaker
for your PV-plant:
• cable type (material and isolation)
• ambient temperature of the cable (higher temperatures reduce the conducting ca-
pacity of the cable)
• type of installation for the cable (can reduce the conducting capacity of the cable)
• bundling of cables (can reduce the conducting capacity of the cable)
• loop impedance [Z] (reduces the current that flows in case of a ground fault cur-
rent through a body and has influence on the tripping characteristics of the circuit
breaker)
• Adequate clearance between the circuit breakers in order to avoid excessive he-
ating (automatic circuit breakers trip earlier when they are warmer)
• fuse selectivity
• protection class of the connected consumer (VDE 0100 Part 410 "Protection
against electric shock" 1 and/or the international standard IEC 364-4-41:1992)
An example for determining the rating of the AC circuit breaker is specified in detail
in chapter 9 „Sizing of a Circuit Breaker” (page 37).
The Sunny Boy 3300TL constantly monitors the ground currents of the PV plant (PV
modules, cables and inverter) and disconnects from the grid when the ground fault
current deviations exceed 30 mA. The inverter automatically distinguishes between
real failure currents and normal capacitive discharge currents.
The following standards have to be complied with:
• DIN VDE 0298-4
1
("Types of cable installation and conducting capacity")
• DIN VDE 0100 Part 430 1 ("Protection measures for protection of cables
and conductors in terms of overcurrent") and/or the international stan-
dard IEC 364-4-43:1977 and IEC 364-4-473:1977
• VDE 0100 Part 410
1
("Protection against electric shock") and/or the inter-
national standard IEC 60364-4-41:1992
1. The standards mentioned above are to be only used as a guideline for your in-
stallation. They apply for installations in Germany. Please note that other stan-
dards will apply for different countries throughout the world.
Do not equip the AC circuit with a 30 mA GFCI (Ground Fault Current Interrup-
tor) that trips when the residual failure current to the equipment ground (PE)
exceeds 30 mA.