This piece was originally published in the May/June 2019 issue of electroindustry.

Muhammad Ali, Program Manager, NEMA

U.S. sales of electric vehicles (EVs) passed the one million milestone last September. Electric vehicle supply equipment (EVSE) is critical to the performance of electric vehicles. This equipment is usually exposed to overvoltages and surges and can result in severe damage to the charger and the car itself. A surge is a brief spike in an ac or dc cycle— less than a millisecond.

The best way to minimize the risk of a surge is to install a surge protective device (SPD). An SPD is “a protective device for limiting transient voltages by diverting or limiting surge current; it also prevents continued flow of follow current while remaining capable of repeating these functions.”

An ideal SPD diverts a harmful surge current to ground under a surge condition and appears as a high impedance under normal operating conditions. For more information about SPDs, please visit the NEMA Surge Protection Institute website at www.nemasurge.org. ei