Electrical "Odds-n-Ends" for Model Railroading Enthusiasts                         

Surge Suppression & Model Trains: A Little Background: 

In 2001 we posted a thread asking who would be interested in surge protection and what kind of products were people currently using.  Response was huge and initially we were looking to design a low cost, bare bones protection device.   But the more we studied industry requirements, the more apparent that quality protection products were becoming a necessity.  PC boards (electronic e-units/sound boards) on trains have been getting fried from voltage spikes and at that time there were inferences that manufacturers may not honor warranties for said boards when used on a layout without protection.  Note new and old transformers can possibly cause voltage spikes.

Then, with the introduction of DCS™ (a MTH® registered product) a new problem arose.  Older transformers with slower reacting circuit breaker protection can generate amperage spikes in a short circuit situation causing the TIU unit (MTH® registered product) to eventually fail.  (Note: second generation TIU-s include internal fuse protection.)

Where do voltage spikes come from?  

Though most of the equipment in our hobby contains limited over voltage protection circuitry, they're no match for some of the spikes they're exposed to.  Studies have shown spikes from 36.8V generated by our ZWs and Z4000s, to as high as 50-60 volts (per a QSI September 30, 1998 white paper).  Such voltage spikes can be encountered in derailments, use of a horn/whistle button at higher speeds (creating higher voltages), shorts from passing over switches, bumps that cause the engine's wheels or rollers to lose contact with the rails, as well as hitting the direction button quickly.   Amperage spikes, as high as 25 amps, have been recorded from older transformers encountering a short, and they don't contain circuit protection or fuse protection as required by today's UL specifications.   The other element our trains are exposed to is "noise" which is also damaging to PC boards, for example but not limited to operational accessories.

Scott's Odds-n-Ends Solution:

Initially in 2001 we teamed up with a second-party surge protection manufacturer and marketed the DTK series of surge protection devices.  They were very helpful in analyzing our needs a suggesting a product that would perform as needed.  In March '07 we introduced our own TVS surge suppressor manufactured specifically for model railroad applications. 

The new TVS-4 is a voltage surge suppressor with four (4) individual channels.  Upgrades from the previous version include newer generation transorb technology, spade terminals for easier hook up for many possible wire gauges, ground connection as with previous product and a separate FB-4 fuse block with 15A fast blow fuses - and lower price so allowing the surge protection device to be cost-effectively applied in more applications including multi locations on a layout or even accessory circuits (for noise reduction).

How does it work?

Transorb technology reacts to over-voltage as opposed to fuses or circuit breakers which in essence react to changes in temperature (heat) from over amperage.  Reaction time is a fraction of a second.   Plus, a fuse or a circuit breaker will never "see" a voltage spike, and it's these split second spikes that zap our equipment.  Another feature is we connect the surge protection to house ground (i.e. center screw on a electrical wall plate) which provides a path of least resistance to route dangerous spikes away from the layout rather than just dissipate or even store within the device.  The cool thing is unless there's a derailment, you probably won't witness any disruption in train operation!  We include fast blow fuses as a precautionary measure specifically related to derailments and dead shorts.

What about use with Command Control systems?

The TVS-4 performs equally well with conventional systems, Lionel TMCC® or MTH DCS™ without degradation the command signal.

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Last modified: August 06, 2011