The Role of Surge Protectors
Surge protectors, in reality, are a type of voltage-limiting device, typically utilizing varistors with high-pass, low-resistance characteristics. When the electrical grid operates under conditions not exceeding the maximum continuous operating voltage (Up), the gap between the two electrodes in the surge protector remains in a high-resistance state. However, if the electrical grid experiences a voltage exceeding the ignition voltage between the two electrodes due to lightning strikes or overvoltage events, the gap is bridged, releasing the overvoltage energy through arc discharge. After the transient surge, the arc is extinguished by an arc-extinguishing system composed of arc-diverting elements and an arc-quenching chamber, restoring the surge protector to its high-resistance state to safeguard the entire system.

combiner box

The Role of Pre-Surge Protection Devices
In case the surge protector itself malfunctions and remains in the connected state for an extended period, this can lead to a short circuit in the power supply or system. To prevent this, it is essential to install a circuit breaker or fuse in advance of the surge protector to promptly cut off the grounding circuit, ensuring the normal operation of the circuit.

Why don’t the pre-surge protection elements trip or open when the surge protector is functioning?
The surge protectorwe use is designed to protect against transient surges, which are characterized by high peak voltages, large currents, and extremely short durations, rather than powerful lightning strikes capable of causing catastrophic damage. Circuit breakers or fuses require the accumulation of a certain level of energy (thermal energy) before they trip or open. Thus, during the operation of the surge protector, transient lightning strikes do not have the capacity to trip the circuit breaker or open the circuit.

Pv Combiner Box 4

Purpose of Installing a Fuse or Circuit Breaker before the Surge Protector

To prevent damage to the surge protector and its associated circuits caused by continuous, low-frequency current resulting from lightning strikes (especially for air gap discharge-type devices).
Facilitating maintenance and replacement of the surge protector; pre-installed fuses or circuit breakers can isolate the surge protector, disconnecting it from the circuit.
To guard against line faults resulting from the aging of the surge protector (such as an increase in leakage current for MOV devices).”