SMA SB 5000TL Multi-String Installation - Manual (Page 16)

Requirements for the Installation SMA Technologie AG
Page 16 SB5000TL-12:SE2006 Installation Guide
Sizing of a circuit breaker for the AC line of a photovoltaic invert-
er 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 surrounding the cable (higher temperatures reduce the con-
ducting capacity 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
heating (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 8 „Exchanging Varistors” (page 33).
The Sunny Boy 5000TL Multi-String 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 distinguish-
es 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
installation. They apply for installations in Germany. Please note that other
standards 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.