Determining The Size Of An Inverter Circuit Breaker - SolarEdge Delta SE12.5K Installation Manual

68 Determining the Size of an Inverter Circuit Breaker
The current limiting devices should protect the electrical circuits and the inverters
from the excess current created by an overload, or a short circuit. If a short circuit or
other overcurrent occurs, the current limiting devices should block the current flow
to the circuit, thus preventing damage to the electrical circuits and the inverters.
The circuit breakers and the fuses should comply with the transformer manufacturer
recommendations and with the relevant sections in standards such as IEC 60909, IEC
60364, UL 508A and NEC 2017.
Some manufacturers provide detailed information about the transformer short
circuit calculation procedure, and its effect on the selection of circuit breakers and
fuses at the different hierarchical levels of the installation topology (see Figure 38 ).
For an example of a calculation, refer to:
Guidelines on the Short Circuit Current Rating for Industrial Control Panels
Short-circuit current rating (SCCR) of industrial control panels
To ensure that the circuit breaker and fuses trip as expected, follow their
manufacturers' recommendations, especially with respect to the various de-rating
considerations.
NOTE
Transformer procurement, installation, maintenance and support are the
responsibility of the installer. Damage to the inverter due to incorrect
transformer installation, or use of a transformer that is incompatible with the
SolarEdge system will render the SolarEdge warranty invalid.

Determining the Size of an Inverter Circuit Breaker

This section explains how to determine the rate of a circuit breaker next to an inverter.
For an example of an inverter with a circuit breaker next to it see Figure 38 .
Ensure you have the following parameters before determining the circuit breaker size:
The inverter's maximum continuous output current as appears in the datasheet.
Factor for the installation's country. This factor is dictated by regulation, applicable
standards or common practice and is usually 1.25.
To determine the size of an inverter circuit breaker:
1. Multiply the inverter's maximum continuous output current by the factor.
For example, 40A x 1.25= 50A
2. Round up the rated size, as calculated in step 1, to the closest standard circuit
breaker size. See Circuit Breaker Criteria table below for standard sizes suitable for
SolarEdge three phase inverters.
Three Phase System MAN-01-00505-1.5