Hello Readers,

Two stories in the “The Dynamo News” described what happened when an unexpected lightning-induced power-line surge ended up at their RV’s power outlet.  If you have every watched a raging thunderstorm that was filled with lightning strikes, you quickly gain a feeling that lightning can be dangerous.  And there is one thing that virtually everyone knows and that is that lightning strikes when it is least expected.

Many experts are quick to tell us that an automobile is one of the safest places to be during a lightning storm.  While that statement may be true (and I am not going to say that it is not), the same may not be true for an RV that is hooked up to an RV Park Power Post.  The reason is that automobiles are not connected to the Earth, as is an RV.  RVs are connected to Earth through their Ground Wire (i.e – the Green wire in the RV’s Power Cable).  It is this wire that the RV relies on to safely carry the excess power line surge current produced when lightning strikes a nearby power line.

All wires have a fixed limitation on the amount of current that they can safely conduct.  To help understand this limitation, consider the following.  Weather scientists tell us that an average lightning strike may produce a current in excess of 40,000 amps.  A quick calculation will reveal that this is more than 1000 time the rating of a 30 amp Power Cable.  To expect that an RV Power Cable should be able to safely conduct one tenth of this current is way beyond a reasonable requirement.

But, applying some Engineering calculations will reveal that there are methods that can be employed to help the RV Power Cable survive a dramatic power surge on the AC power line.

Power surges typically are defined as an extremely short burst of electrical energy that appears on a power conductor.  It is the steeply rising voltage and current in the power surge that results in breakdown of the Power Cable’s insulation, and when this happens, the Power Cable is destroyed.

One way to assist the Power Cable in surviving a dramatic power surge is to modify the shape of the rising voltage and current in the RV Power Cable.  One way to do this is to add additional resistance to the Power Cable.  However, this method is effectively de-grades the Power Cable.

A second method is to add additional “Reactance” to the RV’s power system.  Reactance is a technical term for resistance that is only present in an Alternating Current power system.  Now understand that all RVs operate on AC (Alternating Current) as their primary power system.      

Since this is the case, we can now determine how to apply this “Reactance” to the RV’s Power System.

Let’s start with the basics.  First, all transformers exhibit reactance to some degree.  But, generally, the reactance minimized.   Transformers similar to those used in standard RV Voltage Boosters have minimal reactance so that they operate efficiently.  This fact does not allow standard Voltage Boosters to provide any significant limiting to surge voltage and current.

On the other hand, transformers CAN BE designed to include Reactance in their design.  This type of transformer, know as a “Reactor”, can provide significant limiting to surge voltage and current.

The DYNAMO! Voltage Regulator/Booster is one product that includes this unique type of transformer.  More information about DYNAMO! is on the Web Site. www.dynamorv.com

Stay safe,

Tech Support