In the event of a lightning strike or surge the surge arrestor conducts the charge bleeding it out of the circuit to ground.

PV systems are mounted in locations vulnerable to lightning. The cost of surge protectors are negligible compared to the cost of the equipment being protected.  Consider installing both a DC and an AC surge protector within your system. The DC surge protector can be mounted close to and electrically prior to the solar charge controller.  The AC surge protector can be mounted on the AC load or distribution panel. Both should be connected to the grounded service conductor, or service equipment grounding conductor or a separate grounding conductor.

Models Available:

• LA 302 DC - DC Protector
• LA 302      - AC Single Phase 3 wire
• LA 303 R    - 3 phase light duty 125 - 250V
• CA 302 R   - AC Protector Rated Voltage - 250V single phase, three wire Voltage to neutral - 125V. An internal automatic discharge circuit is provided.
• TA 304 Data line - Two Pair, data line circuit protector w/separate ground. Max. Energy: 750 Joules per Line.  Response Time: 5 Nanoseconds
   

A lighting and surge arrestor for DC circuits and applications, such as photovoltaic (solar electric) systems and cathodic protection systems for pipelines.

The basic design of the DELTA silicon oxide varistor (SOV) arrestor is a pair of metal electrodes separated by a silicon oxide compound. Under normal conditions, the silicon oxide is a good insulator so that no line current flows between the electrodes to ground. When an excessively high voltage occurs on the electrodes, the high energy electrical field ionizes the silicon oxide, changing it from a compound to silicon separate from oxygen. Since the silicon ion is a good conductor, the high energy current is conducted to ground. When the voltage falls toward normal, the silicon and oxygen recombine, forming silicon oxide and shutting off the conduction.

The DELTA silicon oxide varistor (SOV) arrestor has no spark gap. Valve arrestors have a spark gap to prevent line leakage current and to determine the spark-over voltage. Since the DELTA silicon arrestor conducts at the ionization potential, no spark gap is needed. This is more effective because spark gaps cause high-intensity voltage spikes which act as surges and damage electrical equipment. The DELTA silicon oxide varistor (SOV) arrestor works equally well in both directions.