Dyness Knowledge | A Brief Introduction to AFCI

In photovoltaic systems, the DC side component circuit often has a high voltage of about 600-1000V. When the DC circuit has cable connection aging and corrosion, connector failure, model mismatch, virtual connection, insulation material damage and other reasons, DC arc may be generated. DC arc is the continuous spark generated by the current breaking through the air at the circuit breakpoint. DC arc has no zero point, and its harm is far greater than AC arc. Once it occurs, it will cause the conductor contact temperature to rise sharply, generating a high temperature of 3000-7000℃, which will melt the fuse and cable in the mild case, and burn the components and equipment in the severe case, causing fire. According to statistics, more than 80% of fire accidents in photovoltaic power stations are caused by DC side faults.

Therefore, solving the DC arcing problem is a necessary condition to ensure the safe operation of the photovoltaic system, and AFCI technology is a safe guard for the inverter. AFCI (Arc Fault Circuit Interrupter) is an electrical protection device specifically designed to detect and disconnect arc faults. Arc faults can be caused by damaged wires, loose connections, or aging insulation, which have the potential to cause fires. AFCI identifies these dangerous conditions by monitoring current and voltage waveforms and quickly cuts off the circuit when detected, thereby preventing fires.

The functions of AFCI include detecting arc faults, disconnecting circuits, overcurrent protection and electrical safety, etc.

(1) Detect arc faults: AFCI can detect and differentiate between normal operating arcs (such as arcs generated by switch operations) and dangerous arc faults (such as arcs caused by damaged wires or loose connections).

(2) Disconnect the circuit: When an arc fault is detected, AFCI will quickly disconnect the circuit to prevent overheating or fire caused by the arc.

(3) Provide overcurrent protection: Many AFCI devices also incorporate overcurrent protection, similar to traditional circuit breakers, capable of cutting off power when there is an overload or short circuit in the circuit.

(4) Improve electrical safety: By preventing fires caused by arc faults, AFCI significantly improves the safety of electrical systems, especially in aging or dangerous electrical lines.

In general, DC arcs are usually difficult to detect, which means that false alarms and missed alarms must be prevented. The introduction of AFCI technology has effectively enhanced the safety performance of photovoltaic inverters. By optimizing the algorithm, arc faults can be quickly detected and instantly cut off, which has better adaptability than traditional solutions.

Author: Ven Li

Dyness Digital Energy Technology Co., LTD

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