Wednesday, November 14, 2012

Surge Suppression

Although I have written about our product line of transient voltage surge suppression, I have not addressed the correct way to apply or install them.  The main reason I suppose is due to the fact that every application is different.  Many factors come into play in the application of  a SPD (Surge Protection Device).  They can be located or applied in various ways depending on the system configuration, size and of course voltage. 

There are several types and styles for various applications.  And within those there are many voltage options to match up to your type of feed and voltage level.  Saying this, it is probably best to talk to us about concerns and or problems you have encountered.  At that time we can review your entire electrical system if necessary based on your need or concern.  We can then recommend a product or products you may need to best fit your application. 

A little bit about installation:

One of the most neglected parts of making your device work as intended is proper installation of the device.  Correct installation is absolutely a must in order for the SPD to do it's job as it was designed to do.  I really can't tell you how may installations I have seen that are completely ineffective due to the lack of knowledge of the installer.  I am not an expert on the cause and effect of a voltage/current event and the effected di/dt of dv/dt on the system.  What I do know is that a properly installed TVSS or what we now call SPD will greatly reduce the effect and damage normally seen on a typical electrical system.    

When installing a SPD or surge protection device, it is best to mount it in a way that will result in the shortest lead length you can possibly connect with.  Doing this, you reduce the overall inductance of the connection path to the device.  Just to give you an example, one study I read measured a rise in let-through voltage of 100% at just eighteen inches of lead length.  The study also found a 400% increase at just fifty four inches.  This is significant when you think in multiples your applied system voltage plus tolerance.  The recommended lead length for connecting your SPD is six inches.  This is typically impossible on a large switchboard as it is more than six inches from any possible connection point in the switchboard to a location where it is within the NEC code to properly mount the SPD.  This is however very possible on sub-feeder panels where the sides of the panel have a more narrow wireway.  These are typically within six inches of a breaker that can be a landing point for one of these devices.

It is also helpful to twist the leads together if at all possible between the device and the connection point.  This helps reduce inductive coupling which also may lead to a reduction in time to the device.  A seemingly small thing but this is measured in micro-seconds (or less) and is extremely important in the overall reduction of the spike or surge.  Following these two application rules will make the SPD much more responsive when a spike or surge happens, thus reducing or eliminating completely the damage that is normally associated in one of these types of events.

We could spend all day talking about best practice for placement, sizing and installing a SPD.  Trust me when I say that every application is different.  It is important to spend the time with someone that understands surge protection.  That way they will be able to recommend the proper device or devices for your application based on your specific need.  The above information is mainly directed to the person that is or will be installing these devices.  Just by following the advice that I have given you will result in a device that is at least installed in a way to make it as effective as possible so long is the placement is correct.  As always, you can call me for more information regarding this matter.


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