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Rating for a Line Circuit Breaker SMA Technologie AG

Page 56 SB25_30-11:SE0307 Installation Guide

When selecting line circuit breakers, a number of load factors need to be taken into

account. These can be found in the respective data sheets.

For example, one manufacturer's circuit breaker may be designed for an ambient

temperature of 50 °C.

Load factors according to data sheet specifications:

• Reduction through permanent load >1 h = 0.9

• Reduction factor when 9 circuit breakers are arranged side-by-side without gaps

= 0.77

• Increase in nominal current as a result of ambient temperatures of 40 °C in the

circuit breaker panel = 1.07

Result:

The nominal load current for the line circuit breaker is calculated as:

Ibn = 16 A x 0.9 x 0.77 x 1.07 = 11.86 A

Example for the thermal selection of a 16 A line circuit breaker with B sensitivity

and no gap between the circuit breakers:

1. Permanent loads of longer than 1 hour are possible in photovoltaics.

When only one circuit breaker is used, this factor = 1.

Due to the fact that the circuit breakers are rated for 50 °C.

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PV Powered 2500 Guía de instalación Pagina 56