Surge Testing Guidelines

The ever increasing awareness of the sensitivity of electronics to surge effects led to a whopping number of surge suppressors on the market nowadays. Surge testing is very important to apply to electronic devices like air conditioning units, dryers, furnaces, microwave ovens, power tools, water heaters, washers, TV sets, and other home appliances as manufacturers may face liability if their devices were proven to be the root or main cause of a fire related property loss or death. Also it can make a company's products more reliable by reducing its cost, expense and improve its customer satisfaction.

The surge applies a great deal of stress to insulated surfaces which, if compromised, can allow power line current to be partially shorted creating a very dangerous, self-sustaining hazard. Atmospheric discharges [Lightning], nuclear reaction, or switching actions can all produce surges. It can originate from a direct strike to a circuit whether it is a primary one or secondary. The standard protocol to simulate surge testing is a combination of wave which is generated by a generator. It is usually done by coupling to signal certain lines where it is applicable.

Back in the old days of electro mechanical devices, the only effective alternative to hi-pot testing is surge testing which focuses at demonstrating the strength of certain equipment. The traditional tests were performed by specialists in high-voltage laboratories. The test also detects pre-damages that are not yet recognized as short-circuit electric interterm. Although, this type of test must be carried out only by a qualified personnel who can take absolute precaution as the energy involved will be extremely high. Such evaluation can avoid thermal, electrical, and energy overstress, and even damage to electronic devices. Confronted with such difficult choice, there are quite a few users that are evaluating the performance of these devices by surge testing all on their own.

The surge test is mainly a test to determine the power supply's ability to withstand such high-energy pulse. If there is no surge protection device installed, a test that is only high enough for immunity test level specified will be conducted. In such case, testing at lower immunity test levels is not useful and would provide no additional information. If a surge protection device is installed, then testing at lower immunity test levels is necessary to verify proper operation of the surge protection device.

Preferred protection devices consist of Metal Oxide Varistors - MOV's or widely known as insulated isolation transformers. Most of the time, other methods of control are ineffective because the surge current/voltage is high enough to saturate magnetic structures and break down insulation. Protective Metal Oxide Varistors devices usually display a wear out mechanism with lots of surge applications after which there's a high chance they may explode, overheat or destruct catastrophically. For this matter, manufacturers prefer the use of well built and constructed isolation transformers just to lessen the severity of the pulse. Due to high-risk potential of adverse unknown effects, surge testing requires a well-spaced interval. All test operators must be fully aware of a possible safety hazard when dealing with surges and applying them to shielded cables. A faulty shield connection can result to high impedance to the ground reference.

There is more to surge testing than connecting a test article to the output terminals. Every aspect of testing must be considered and coordinated.