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I recently sent a post concerning a problem I have in frying MTH turnouts.  I have also fried a circuit board in a modern o guage Lionel Loco.  Obviously I need appropriate circuit protection but I am not an electronic person so I need to know ,in laymans terms, the best way to protect my layout.  I have heard of inline fuses, PTC's, miniture breakers etc.  But which one and at what level of protection?  Any specific and simple to understand response would be appreciated.

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 You should also list more of the info because frying turnouts may be another issue; e.g. two transformers, wiring, or your voltage setting or more might be at fault. Are the coils cooked or boards?  Are you parking trains on an anti derail feature? Used a solid pin vs isolation pin (?mth?), ..etc... But, on to the fusing.....or actual electeonics protection*  

  It is a matter of application and preference to get ro best. The fuse, ptc, traditional thermal beaker, and magnetic breakers all serve the same function but do it in a slightly different manner. 

  The PTC resets automatically, similar to the old electromechanical breakers of post war. They have the benefit of not dropping out on a fast but high amp draw.  "They average draws" allowing a cusion of higher amps by for a split second without dropping out.

Magnetic ones (mech. or electronic) are more senstive, and faster acting, but that includes not liking sparks, rollers clipping power, etc.. Adjustability can be worked into a homespun, and the post war magnetic are adjustable though a split second slower than a electronic companant version.

The auto-reset might not be considered ideal. Breakers needing manual reseting means you can rerail, the attend to the breaker. With auto reset you have a race to the throttle or power switch before the reset or you risk again (lower maybe, breaker IS working).

Breakers have an advantage over fuses, in that fuses burn; a cost.

Fuses are thermal, but have an advatage in great instant adjustability to any situation (slow blow,normal, fast blow, etc.). 

 * Protect sounds and electronics specifically with a transient voltage suppressor (TVS)  At one per item or at least 1 per transformer power terminal set that you use (1-a&u +1-b&u or 1 red&blk +1-accessory a&b...etc). , Mount it common to hot/ 1&2/ center rail to outer rail, Red to Blk., etc. 

  I do still use fuses a lot to "dial in" or on isolated circuits not prone to being tripped, but I also have a bulk supply from appliance/coin op repair, and hot rodding. In the long run, breaker's can be cheaper, but mostly they are very convenient to reset.

Ideal-

post war- Thermal is in transformer, magnetic on each line, tvs.

Modern electronic - "magnetic"(=) inside, fuse/breaker on each line, tvs.

(some dcs command units have internal tvs, but adding another is great too. They do die. Add ten if you want    )

From my old notes:

Inexpensive Transient Voltage Suppressors (TVS) are the best protection against voltage spikes that can damage layout wiring runs and fragile engine electronics. Fast blow Fuses or electronic circuit breakers such as on the 180 watt Powerhouses are the best protection of your transformers against overcurrent  surges. Three TVS shown below, about $.50 each. Breakers such as 10 amp IMG_1763Potter Brumfield from Mouser Electronics and others are about $4 and are comparatively slow at 8-10 seconds. Voltage Spikes that damage electronics and fragile wiring will not trip a breaker as will overcurrent.

 

IMG_2070IMG_2071

 

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  • IMG_1763: 10 amp Potter Brumfield circuit breaker
Last edited by Dewey Trogdon

I've had good service from Airpax circuit breakers.  They are lots faster than an automotive fast blow fuse, or the breaker on an Lionel 180 brick, and you can choose how much delay you want, so the breaker won't trip every time you get a spark somewhere.  In addition to an Airpax I also second the notion of having a TVS on each transformer output tap; between the transformer and the load (track, TIU or DCC device)

Last edited by Former Member

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