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
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.
NOTE
If the result has a decimal fraction smaller than 0.5 round it down.
3. To ensure that the selected circuit breaker trips as expected, at minimum consider
the following:
The circuit breaker rated voltage.
Temperature de-rating due to both close proximity of other circuit breakers and
the effect of ambient temperature on the distribution board.
De-rating due to permanent load.
If the de-rated current of the selected circuit breaker is lower than the maximum output
current of the inverter, consider selecting a circuit breaker that is designed for a higher
rated current, or reducing the temperature de-rating effect by increasing the distance
between adjacent circuit breakers.
NOTE
Make sure to select cables that are suitable for the environmental
conditions, the operating voltage and the selected circuit breaker.
Three or four pole circuit breakers are required. It is recommended to
use a four pole circuit breaker when applicable.
It is recommended to use a circuit breaker with tripping characteristic B
or C.
Appendix E: Determining the Circuit Breaker Size
95
Three
Phase
System
Installation
Guide
MAN-01-00527-1.
2
