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Post by JDaddy on Oct 17, 2024 14:24:55 GMT
Just a note from my experience. I had a short in one channel of the TIU. The variable channel 1. I noted two things when I connecting the TIU directly between the transformer and track:
1) The TMCC signal was grounding out in this channel - even if the connection was made separately to the track at a different location of the layout
2) Voltage measurement doubled at this channel. instead of 18 volts, measurements read from 32volts to 35 volts.
I am not not sure if you are using a DCS TIU with Legacy/TMCC, but this is something to be mindful when running trains after previous short circuit.
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Post by superwarp1 on Oct 18, 2024 18:12:02 GMT
On a side note about RCMC. This is my latest Legacy conversion. 3rdrail L3b Mohawk being converted by the Legacy master Bruk Bannister. He runs is conversions over night. This has been running for 16 hours
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Post by trainman9 on Oct 19, 2024 12:00:08 GMT
QSI did some testing a number of years ago and determined that at that time Lionel boards could withstand a 50 volt spike and MTH boards could withstand a 35 volt spike without damage. The TVS I suggested will direct any spike above 33 volts to ground.
Well I've never heard that before and something I'm not going to try. I have heard of Legacy boards being damaged over 20 volts while running.
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Post by bobthetrainguy on Oct 20, 2024 0:59:34 GMT
I’ve installed TVS’s on my layouts for over 20 years and never had a board failure (knock on wood). Circuit breakers are fine but a TVS with the right configuration will react over many times faster than any circuit breaker. They may be prone to failure but I’ve not experienced that thus far.
If you are really concerned you can construct a simple device to detect a spike using instructions in a document prepared by an electronic engineer and published by the DC Highrailers. .
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Post by superwarp1 on Oct 20, 2024 3:07:24 GMT
I’ve installed TVS’s on my layouts for over 20 years and never had a board failure (knock on wood). Circuit breakers are fine but a TVS with the right configuration will react over many times faster than any circuit breaker. They may be prone to failure but I’ve not experienced that thus far.
If you are really concerned you can construct a simple device to detect a spike using instructions in a document prepared by an electronic engineer and published by the DC Highrailers. . WHAT, where does the spike come from when there’s a short? I can tell you it’s not in the engine
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Post by steveoncattailcreek on Oct 20, 2024 3:44:44 GMT
Unless you install the TVS in your locomotives, they won't do much good. WHAT, where does the spike come from when there’s a short? I can tell you it’s not in the engine It's not a matter of where the spike is coming from, it's where it can do damage -- the electronics on the PCBs, which are typically in the engine or tender. *Anywhere* you put the TVS diodes will probably help some, but putting them directly across the vulnerable hardware is usually best.
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Post by superwarp1 on Oct 20, 2024 13:04:57 GMT
WHAT, where does the spike come from when there’s a short? I can tell you it’s not in the engine It's not a matter of where the spike is coming from, it's where it can do damage -- the electronics on the PCBs, which are typically in the engine or tender. *Anywhere* you put the TVS diodes will probably help some, but putting them directly across the vulnerable hardware is usually best. You want to clamp it at the source. To prevent damage down stream. The only real way to prevent damage and to prevent arch welding wheels to rails is to install a PSX. Installing transorbs in engines is unnecessary
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Post by steveoncattailcreek on Oct 21, 2024 2:47:38 GMT
It's not a matter of where the spike is coming from, it's where it can do damage -- the electronics on the PCBs, which are typically in the engine or tender. *Anywhere* you put the TVS diodes will probably help some, but putting them directly across the vulnerable hardware is usually best. You want to clamp it at the source. To prevent damage down stream. The only real way to prevent damage and to prevent arch welding wheels to rails is to install a PSX. Installing transorbs in engines is unnecessary Well, sure -- if you can reliably predict the precise source and origin of the spike, add the TVS at that point. Since IME a short or other electrical disruption can literally occur at *any* point in the electrical circuit (including metallic objects randomly dropped across the tracks), I maintain that protecting the equipment vulnerable to damage *where that equipment is located* is a better strategy than putting the protective gear possibly half the layout away. You could also do both (TVS diodes are pretty cheap, after all). YMMV, of course . . .
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Post by superwarp1 on Oct 21, 2024 3:01:27 GMT
You want to clamp it at the source. To prevent damage down stream. The only real way to prevent damage and to prevent arch welding wheels to rails is to install a PSX. Installing transorbs in engines is unnecessary Well, sure -- if you can reliably predict the precise source and origin of the spike, add the TVS at that point. Since IME a short or other electrical disruption can literally occur at *any* point in the electrical circuit (including metallic objects randomly dropped across the tracks), I maintain that protecting the equipment vulnerable to damage *where that equipment is located* is a better strategy than putting the protective gear possibly half the layout away. You could also do both (TVS diodes are pretty cheap, after all). YMMV, of course . . . We’ll have to agree to disagree on this one. Since any short would cause the spike to be generated in the transformer, I’ll continue to use my PSX at the output which have transorbs built in. I have no desire to open up all my engines to ad a part which is unnecessary
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Post by trainman9 on Oct 21, 2024 15:29:00 GMT
If you read the CTT report according to QSI you don’t need a derailment to cause a spike they can be caused by a roller pickup losing contact with the center rail. Poor track work can also contribute to a voltage spike.
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Post by steveoncattailcreek on Oct 21, 2024 17:00:47 GMT
Well, sure -- if you can reliably predict the precise source and origin of the spike, add the TVS at that point. Since IME a short or other electrical disruption can literally occur at *any* point in the electrical circuit (including metallic objects randomly dropped across the tracks), I maintain that protecting the equipment vulnerable to damage *where that equipment is located* is a better strategy than putting the protective gear possibly half the layout away. You could also do both (TVS diodes are pretty cheap, after all). YMMV, of course . . . We’ll have to agree to disagree on this one. Since any short would cause the spike to be generated in the transformer, I’ll continue to use my PSX at the output which have transorbs built in. I have no desire to open up all my engines to ad a part which is unnecessary Well, since I run almost exclusively PW conventional rolling stock with little or no electronics, voltage spikes are not a day-to-day issue for me. And sure, *any* protection against voltage spike damage in *any* location is better than none, but it does not take an electronic genius to conclude that locating the protection at the vulnerable point can be more effective than at any other site on the layout. It's up to you to decide what level of protection you want to build in, but with the high cost (and frequent unavailability!) of modern locomotives and their replacement parts, ISTM more is better. As I said, YMMV . . .
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Post by twincities on Oct 22, 2024 11:51:05 GMT
good way early morning to all still waiting on the rcmc board to ship! as for digikey not a first time great users experience 5 days ago I ordered the 10 tvs diodes then its held in billing then they show someone elses order in my account and lucky me not on my card today they fixed that snaffu and finally my order is being processed in shipping you can say how great online ordering is my world retail trumps it way better you walk in grab what you need off a shelf or peg walk to a cashier and out the door you go parts in hand rant over but really I didnt work this hard at a 6-2 job!
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Post by harborbelt70 on Oct 23, 2024 18:14:43 GMT
Possible, If you can figure out a way to keep the board from getting wet, go for it. What's your power to the layout setup?
Regarding getting smoke fluid on the boards, generally modern smoke fluids are not electrically conductive and would not themselves cause a short although I suppose that they might damage solder connections/traces over time. However, I really think that in TwinCities' case the problem of repeated board failures is probably at the power source.
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Post by trainman9 on Oct 23, 2024 18:55:39 GMT
I think it’s Okay to use PW transformers as long as you provide the proper protection with both TVS’ and fast acting circuit protection. I think if you use fast acting fuses you need to replace them if they have been activated. Not sure of the fuses or circuits that allow you to do a reset.
I have a ZW-L and it has several layers of protection but I still have TVS’s installed.
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Post by bobthetrainguy on Oct 23, 2024 22:56:39 GMT
Unless you install the TVS in your locomotives, they won't do much good. WHAT, where does the spike come from when there’s a short? I can tell you it’s not in the engine It's not a matter of the source, it's a matter of what you want to protect. The waveforms generated by derailments, sparks, and shorts are very irregular. When these happen, the load is varying and as resistance, and inductance change, the voltage can swing all over the place. Where at one spot in the circuit, near the derailment the voltage could be exceedingly high, another spot near the transformer could be at the zero crossing. The TVS will do your engine electronics no good there. If the spike waveform repeats long enough then yes the TVS will shut the current to ground, which may or may not cause the circuit breaker to trip depending on the duration. However, by that time the damage to the sensitive electronics is done. Again, TVS devices need to be within inches to centimeters away from the circuitry to protect it against the wild varying high frequency waveforms that are the result of rapid loading and unloading of the transformer. |
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