OK, I've read a little about putting in an in-line fuse. I need to put one in to protect my locomotives from the old Lionel transformers. I like the idea of using the glass fuses, as they would be a sure-fire way to protect and not have to worry about a re-set button/type going bad. So what type of fuse do I need? How many amps? I want to be sure to protect the engine(s) while using an old post war transformer. Thanks.
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I picked up a couple of automotive fuse holders with an assortment of fuses. Haven't installed them yet.
Many guys use quick acting circuit breakers and transient surge suppressors. More effective for protecting boards in modern engines.
I wish we could kill the misconception that circuit breakers protect the delicate electronics... THEY generally DO NOT! They protect the power source and delivery...
The addition of a TVS diode protects against voltage spikes caused by collapsing electromagnetic fields generated by the layout (relays, solenoids, motors, derailments etc). This is necessary for ALL transformers, classic or modern.
A short video about those spikes:
Since the source is layout side, you want the protection layout side. Many people put them on the track, others put them on the output terminals of the transformer, and some do both!
With a ZW, it is easy to take 4 TVS diodes, shape them like this so they wrap around the binding posts, (A-U, B-U, C-U, D-U).
For power supplies in excess of 18VAC use the 1.5KE36CA diodes. If you only use supplies that are limited to 18 VAC then you could get by with 1.5KE33CA diodes or use the higher rated 1.5KE36CA anyway. These can be found from any electronic component supplier such as DigiKey, Mouser, Newark, Amazon.com, eBay and so on...
Note that there's more than just the transformer that can generate voltage spikes. Any coil that has power suddenly removed can generate a spike that can be hundreds of volts. Think of switch machines, accessories, motors, etc.
tvs you use the standard old AGC glass fuses that were used in cars always blow quickly and are very cheap and there are various types of holders u can use! if your only running one engine and maybe some lighted cars 4 amp fuse would be enough. but if your running more then one engine at the same time you would have to use a higher fuses it will depends on your layout. the lower the better. if you fused each engine inside 4 amps would be good. all depends how far you want to go with your protection! some techs even put tvs diodes inside there engines to stop damage, the only problem is when the tvs diodes short you'll have to take engine apart to replace tvs diode . the bad this is sometimes a tvs diode will fail open and then your not protected at all!
Alan
Jeff B. Haertlein posted:. So what type of fuse do I need? How many amps?
Lot of good info, but it doesn't seem that your questions have been answered.
"So what type of fuse do I need?" Bussman Of course, you'll need a fuse holder too.
"How many amps?" Depends upon the transformer. A PH180 (for example) 180W/20V = 9A. Not using a brick? No problem. Set your transformer to 100%. Say for example this is a 90W transformer and you measure 17.5V so...… 90/17.5 = 5A
Fuses should be sized to protect the wires that feed your tracks.
https://www.engineeringtoolbox...re-gauges-d_419.html
Fuses should be sized to protect the lowest ampacity component in the circuit. Electronic boards are damaged by voltage spikes, not by excessive currents that are not flowing through the boards. The TVS diodes are the protection from spikes. Glass fuses can get to be very expensive. I use breakers in line with fuses, the fuses having slightly higher amp ratings than the breakers and intended to be backup protection. I have never had a fuse blow--the breakers open first. I size the breakers based on the number of trains that might be operating on the particular channel (I use 6 TIU channels)
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