Powerline Surge Suppression Simplified

by J.R. Harford

The technical terms used by powerline surge suppressor vendors are very confusing, and since testing these devices is impractical, vendor information must be relied on, which leads to abuse.

• The confusion can be reduced by comparing the technical terms for stopping a surge to stopping an automobile, something most of us understand.

Assume you are in an automobile traveling at 65 miles an hour. A fallen tree appears ahead. What do you need to know about your brakes?

You need to know if your car will stop before it hits the tree, so stopping distance is extremely important!

At only 5 miles an hour, the stopping distance, brake wear and danger are minimal.

Suppressor vendors often supply a "response time," and a "clamping level." These relate to when you first put your foot on the brakes (response time), and the initial braking effectiveness (clamping level).

• What is really important, however, is the total stopping distance which includes "response time" and "clamping level" (will you hit the tree?) Total stopping distance is like surge suppressor "let-through voltage." But there is a problem.

Manufacturers use different surges to test suppressor performance, the powerful 6,000 volt 3,000 amp pulse, the weak 6,000 volt 500 amp ringwave and the tiny 200 amp ringwave are often used.

The analogy here is the stopping distance at 65 miles an hour (for the powerful pulse) and at 5 miles an hour (for the ringwaves). Which is more important? What should you think of a product that only gives its stopping distance at 5 miles per hour (ringwave) and offers no performance at 65 miles per hour (pulse)?

The weak 6,000 volt 500 or 200 amp ringwaves are used by many vendors since they have 13 to 35 times LESS destructive energy than the powerful 6,000 volt 3,000 amp pulse and it significantly inflates their performance.

So what is necessary for comparison?

1. What is the stopping distance at 65 miles an hour? (What is the let-through voltage for the dangerous 6,000 volt, 3,000 amp surge?)
2. How many times can my brakes stop the car going 65 mph? (What is the endurance rating for the dangerous 3,000 amp surge?).

A joule rating and a peak surge current rating are often supplied. These are technical terms which describe limitations of MOV technology products, and they relate to endurance, but you have no way of determining the endurance from these numbers. Instead of joule rating and peak surge current rating, look for an actual endurance rating for the dangerous 6,000 volt, 3,000 amp surge pulse, the largest surge industry standards recommend.

The US Government defined two MODES of operation. Mode 1 is the ground protection mode, since it doesn't surge the ground wire. Mode 2 surges the ground wire putting interconnected products at risk. Products claiming "all three modes of protection" are US Mode 2 products, since they divert surges to the safety ground wire. Avoid these.

• In summary, if test results are only provided for the ringwaves, do not use for important applications. If your application is important, compare the following performance for the dangerous 6,000 volt 3,000 amp surge pulse:

1. Let-through voltage (lower is better).
   
   
2. Certified endurance (100 - 1,000 surges).
   
   
3. Mode (1 or 2) (Mode 1 is better).

If this information is not offered, or only test results for the ringwave are provided, or they do not say which surge was used, or no endurance is given at all, there must be a good reason -- don't gamble on these products!

Manufacturers with nothing to hide WILL supply the information you need. Avoid the other products! In this case, ignorance is not bliss. It may lead to very costly down time or lost files!