Lightning Testing and Surge Immunity Testing

Keystone Compliance has established a solid reputation of being an industry leader in surge and indirect lightning testing. The effects of indirect lightning effects can be severe on equipment and components.

What is an indirect lightning strike?

An indirect lightning strike can occur two different ways. The first way is what is called a side flash. Indirect lightning side flashes occur when the current jumps from one object to another. This jump occurs through the air and can be for considerable distances. The second type of indirect lightning strike is from a ground current. Essentially, the lightning reaches the ground and then travels to another object. The impacts of indirect lightning strikes can occur over a half of a mile away from the site of the lightning strike.

What impact can an indirect lightning strike have on equipment?

The indirect effects of lightning on electronics can be significant. The sudden rush of electromagnetic energy and voltage is carried by device’s cabling. The surge of energy can damage cables and connected components as it takes a path of least resistance. The indirect lightning effects can be originated from the ground, power lines or metal objects that the device is either connected to or near.

Aircraft equipment is very susceptible to indirect lightning. The aircraft, cables, boxes, controls can all be impacted by the electromagnetic surge from a lightning strike.

How is indirect lightning tested?

Keystone Compliance has invested and/or built a substantial amount of test equipment and custom wave forms. Using generators, burst generators, high-power amplifiers and RLC circuits, our engineers can develop the test setup needed to simulate any lightning strike voltage.

The testing, also referred to as surge immunity testing, can be completed on components, cables or entire systems. The transient wave shape is simulated by the test equipment and injected on to the device(s) under test. There are multiple types of injection methods used. These include capacitive injection, ground-current injection, pin injection and transformer injection.

In addition to the injection method, the impact of indirect lightning testing can vary based on the wave form of the strike. For instance, indirect lightning testing methods can require single stroke, multiple stroke or multiple burst pulse sequences.

How can the effects of indirect lightning be mitigated?

On airplanes and airplane equipment there are several design methods that can reduce the effects. First, adding new conductors to carry the lightning’s current is highly recommended. Adding bond straps and reducing the bond impedance between components and equipment. Terminal and circuit protections should be prevalent and increasing the size of cable shields is important. On other equipment, the using of shielding, surge protectors and circuit breakers are encouraged.

Power surges and indirect lightning currents are complex. They are not predictable but their effects can be devastating. Partnering with a competent lightning test lab like Keystone Compliance is crucial. Our team can simulate the effects of power spikes and surges in a controlled laboratory setting. Surge immunity testing labs are a critical partner in the certification of aircraft devices and related electronics.

Contact our indirect lightning test experts to discuss your device and the testing it must undergo. In addition to completing the testing, we can also assist in developing the test plan. We are accredited to nearly every active indirect lightning standard but also have the ability to generate custom wave forms, specialized pulses or long duration electrical surges as well. Find out firsthand why so many companies and agencies rely on Keystone Compliance for their EMC surge immunity testing.