Panamax and MOVs

On several places on the internet, people like to bad mouth MOV based protectors. Much of it is instigated by companies selling other technologies. Some, are based on historical facts. Others use cheap products to make blanket statements about all protectors of a given class. Allow us to clear this up... Let's start with a simple, fact based MOV technical note based on real protectors in the field.

MOV based protectors have been around a long time. Historically, there have been some pretty bad or cheap MOV based protectors, no doubt about it. Also, there were (and are) certain types and designs of MOV based products that were subject to catching on fire under certain conditions. Some MOV based protectors use, well, cheap components and inferior designs and can only handle smaller surges. Some, break after one decent size surge. But, does that mean ALL MOV based protectors are bad? Like any product, using cheap components or badly designed products yield bad results. Just like computer programs can be badly designed and cause numerous problems, so can surge protectors. Properly utilized, MOVs are an integral part of a very effective protection scheme. Panamax protectors DO use MOVs in many cases. This is a GOOD thing, not a bad thing. MOV based protectors have incredibly fast response times, far faster than most other technologies. MOVs are very good at clamping spikes and for many other reasons.

The UL 1449 second edition rating for surge protectors is an important rating. The second edition addresses the problems with the older or cheaper protectors. A good MOV based product meets those standards. The second addition provides for a number of changes. These include:

• Thermal fuse protection against protector meltdown
• Protectors safe against catastrophic overvoltage
• Protectors safe against leakage or shock after damage
• Must survive a minimum of 2 3,000Amp and 20 500Amp surges
• Must protect Line-Neutral, Line-Ground, Neutral-Ground
• A new test that connects the protector to 125% of normal voltage for 7 HOURS
• A simulated loss of neutral test, a 120V protector will be subjected to 240V.
• And more of course... This is just a summary

Any surge technology has weaknesses, every single one of them. So, a good protector might use a variety of technologies, each of which handles the types of surges and conditions they are good at. Smaller surges are easily handled by a good MOV based product, more effectively than other technologies. Other types of surges, and there are many kinds, are handled better by other technologies. So, a quality protector proven in the market should employ a variety of technologies. But what about the claims that MOVs degrade over time? There is an element of truth to that, but, let's look at some data from one surge protection company, Panamax. According to the following MOV technical note, this is not always the case

For example, consider low power events. Low power can fry equipment just as much as too much current, motors can reverse for example. Also, one can have surges on other signal paths (cable, phone, etc.), each type of signal path has different requirements. There are common mode surges. Prolonged surges (say an ice storm causing wires to cross). All sorts of variations. A quality protector handles *all* types of surges.

So, how do the better model Panamax protectors work? MOVs are used for smaller surges, historically, this is the so called Joule rating. What about larger or prolonged surges? A technology called Surgegate handles those types of surges, disconnecting power for the duration of the event, thus protecting your equipment. What about low power events? Surgegate Plus cuts the power during harmful low power events. What about telephone lines, cable lines, satellite lines? Various technologies such as SIDACtors and PTCRs are used, no fusing! You don't want to replace a device all the time. What about marginal surges that might go above some limit but only for a very brief amount of time? The more expensive Panamax models employ a technology called AVM, short for automatic voltage monitoring, which can adjust for and predict surges.

One more item to consider. In a home theater system, with many signal paths sharing a common ground, noise can be introduced into a system which can result in picture or audio degradation. The highest priced protectors also offer filtering to remove various types of noise to provide a better picture or sound. A very large percentage of customers do get noticeable benefits. So, consider this as well in selecting a good surge protector.