The Difference Between a Lightning Arrester and a Surge Protector

1. What's a surge protection device (SPD)?

A surge or spike refers to a transient over-voltage that is far larger than the specified operating voltage. In essence, it is a strong impulse with the duration of merely several microseconds, which may result from switch-on or -off of heavy machinery or large engines, short circuit, or power switching. SPD-integrated products can effectively absorb the huge energy in the wake of a surge, and therefore protected both themselves and connected equipment from damages. The surge protector, also called as lightning protection device, is an electrical device designed to protect equipment, instruments and meters, and communication lines. For details when a spike current or voltage occurs due to electrical circuit or external interference in either communication lines or electrical circuits, SPDs can divert the spike within a short period, protecting other equipment in the circuit from damages.

Considering the distance between surge protection device (SPD) at the first stage of protection and terminal equipment is relatively large, the line may generate oscillation overvoltage or feel other overvoltages. Therefore, a combination of surge protection device (SPD) at the first stage of protection and power SPD adaptative to terminal equipment will provide better protection.

A surge protector includes such basic components as discharge gap, gas discharge tube, metal oxide varistor, suppression diode, and choke coil. Overvoltage protector is a state-of-the-art device to limit overvoltages caused by lightning or human operation. As an advanced device to protect against overvoltages, it is primarily used to protect the isolation of electrical equipment including engines, transformers, vacuum switches, buses, and motors from damages by overvoltages.

2. Major differences between a lightning arrester and a surge protector

(1) From the perspective of voltage levels

The rated voltage of a lightning arrester ranges from less than 3kV to 1,000kV, and the voltage is as low as 0.28kV or 0.5kV.

The rated voltage of a surge arrestor is or less than 1.2kV, 380, or 220~10V~5V.

(2) Different protection target

A lightning arrester is intended to protect electrical equipment, while the surge protection device (SPD) is usually intended to protect secondary circuits or terminal power supply lines of electronic instruments and meters.

(3) Different isolation or voltage-resistant level

Appliances in no way can bear comparison with electronic equipment as regards to the ability to resist voltage. The remaining voltage of a voltage protector should match the voltage-resistant ability of the protection target.

(4) Different installation sites

A lightning arrester is usually installed in the primary system to protect against the direct invasion of lightning strokes, protecting overhead lines and appliances. In contrast, a surge protector arrester is usually installed in the secondary system, which serves as a supplementary method working when the direct invasion of lightning strokes has been completely or partly eliminated by the lightning arrester. In consequence, a lightning protector tends to be installed at the beginning of the line while the surge protection device (SPD) tends to be installed at the end of the line or in the signal circuits.

(5) Different material

A lightning arrester is mainly made up of zinc oxide, which is one of the varistors of metallic oxide. In contrast, a surge protector has a finer design than ordinary lightning arresters. And its main material varies from different levels of surge resistance and protection against lightning: IEC61312.

Technically, a lightning arrester can not bear comparison with a surge protector in terms of response time, voltage limit, comprehensive protection, as well as aging resistance.