Best Voltage voltage protection component for TMCC/Legacy engines

Hi the trouble with derailments is there is quick short which does the damage to your circuit board, even though the breaker may trip and then board ic will be damaged! what would help is tvs diode installed on the engine across the roller and ground! This part can help but to catch the spike by directing shorting the TVS diode! I could help- you by installing ptc fuses which will prevent the over current limit!

send me An email in my profile I will help you any way I can!  Alan

Best protection if you are not going to run conventional is a PSX-AC. Check out my video on them.

Alan's right on track.  It's about putting your protection inside the engine if possible, as close to the protected electronics as possible.  And you'll need protection for both over-current surges (with PTC's) and over-voltage spikes (with TVS diodes).

If you can't put it inside, or don't want to, then Gary's approach is the best, but as he points out only if you're planning on command-only operation.  The PSX-AC won't work below 10 VAC, which is unfortunately the top of the normal operating range for conventional control.

There are other external protection solutions as well though, and some will work with conventional operation.  For instance your ZW-L should have a very fast circuit breaking system in it so you shouldn't need any additional over-current protection other than what it already has.  For over-voltage spikes TVS diodes connected across the terminals of each track connection (at the lock-on) should cover you there.

Mike

Well, a modern circuit breaker like the ones on the Lionel 180 watt bricks has a trip time of something like 50 milli-seconds. Per Tony's Trains, the PSX-AC trip time is on the order of 200uS--a BIG difference. But the devil is in the doggone details of course. You have to pick the current limit for the PSX-AC to trip from among the 4 settings. I have mine wired for 8 amps. That somehow affects trip time. And Tony's also says that power feeder wiring can have an effect on trip time. But you'll have to look that up on their site if that is a concern.

One annoying question is how can you know if the PSX-AC prevented an engine board failure when it trips and the engine is intact afterward? Did it prevent the failure? Or was it luck? I have only had a few trips but zero engine failures. So naturally, I am pleased with the PSX-AC and feel that it gives me the best protection that money can buy without engine modifications.

Don Merz

@Don Merz 070317 posted:

Well, a modern circuit breaker like the ones on the Lionel 180 watt bricks has a trip time of something like 50 milli-seconds. Per Tony's Trains, the PSX-AC trip time is on the order of 200uS--a BIG difference. But the devil is in the doggone details of course. You have to pick the current limit for the PSX-AC to trip from among the 4 settings. I have mine wired for 8 amps. That somehow affects trip time. And Tony's also says that power feeder wiring can have an effect on trip time. But you'll have to look that up on their site if that is a concern.

One annoying question is how can you know if the PSX-AC prevented an engine board failure when it trips and the engine is intact afterward? Did it prevent the failure? Or was it luck? I have only had a few trips but zero engine failures. So naturally, I am pleased with the PSX-AC and feel that it gives me the best protection that money can buy without engine modifications.

Don Merz

Actually, the trip time for an true overload of the PH180 is 10 milliseconds maximum.  It does have a slower trip time for a gradual increase in current that exceeds the 10A rating, the fast trip is for an instant overload.

Well, is my math wrong John? I was overheating my brain thinking that even 1ms is five times slower than 200uS. So if we pick half the 180's maximum as a likely average trip time--5ms--that would be 25 times slower than the PSX-AC. Or am I all wet?

I am feeding my PSX-ACs with the PH180's. On one occasion when the PSX tripped, the 180 also tripped. But on two occasions, the PSX tripped while the 180 did not. Those are my only 3 examples I have to go on.

Don

I guess my basic point is, while faster is certainly better, there's a point of diminishing returns.  There's also a school of thought that too fast a trip is likely to yield false trips where there is no fault.  A long time ago, I used to use the Lionel TMCC Direct Lockon.  It actually was prone to false triggering when nothing was wrong.

There are two common scenarios where there's a possible overcurrent that will trip your circuit protection.

#1: A fault develops in the drive electronics and causes an overcurrent situation.  In that case, I doubt 5ms is going to make any difference, the damage is obviously already done.

#2: A derailment occurs and causes a short.  In that case, 5-10 milliseconds is plenty fast enough to prevent damage to wiring, etc.

I don't doubt the PSX-AC is excellent protection, I just don't believe that the difference between it's protection and the PH180 breaker is all that significant in preventing damage.  In truth, I had several of them connected for several years in my previous house.  I decided they were overkill for my environment and sold them, I haven't had any occasion to regret that decision.

@gunrunnerjohn posted:

I guess my basic point is, while faster is certainly better, there's a point of diminishing returns.

Amen to that.

John