Wiring with Fuse Blocks and Diodes

[cheech]

Back for some more help with wiring. And thanks in advance.

I am still a bit confused about wiring the components in the proper sequence.

It is a big layout for me, 24x16 large C, two levels, lots of switches, lots of operating accessories. 4 main loops, crossovers and it almost all connects at some point. I have isolated the tracks into potential power blocks with plastic pins in the center rail. I have wired a 12g bus. There are 12 potential blocks and 1 common going around the entire table. There will be 4 TMCC Block Controller devices, each with 4 blocks assigned, connected to TMCC TPCs (multiple) and 180W Powermaster devices (multiple). I will have additional transformer ZW 275 to power for lights, accessories and trackside signals and switches (Gargraves/Ross) using dz1000s.

I am trying to protect the power. I understood that the zenner diodes needed to be connected in parallel to do their job and that the fuse holder with re-settable 10a fuses could also help protect the equipment. I found a couple of different fuse holders and I am not wedded to either one. I looked at the scotts-odds-and-ends devices, but it seemed much more pricey with the same connection questions plus there was all this about the ground connections within the electrical power supply box that I was a bit timid about.

I can’t seem to figure out how the fuse block and zener diode get into the mix with the TMCC equipment. I laid out a prototype of the components and took some snapshots loaded onto shutterfly so it could be clear what I was going to do. hope they are large enough to show my confusion.

1. Where would the fuse holder connect ---- between the powerhouse and the tpc?
2. Where would the zener diodes connect ----between the block controller and the terminal strip?
3. The diodes need to be parallel and i chose Euro connectors to illustrate what i was planning
4. One of the fuse holders has a single input, 12 fuses output and a ground. The room is in the middle of a house. what happens with the ground?

Any help or advice would be appreciated. I am not sensitive in the least

http://im1.shutterfly.com/procserv/47b6dd37b3127cce97953cbda7f700000010102AbOGjFq4Zsd
http://im1.shutterfly.com/procserv/47b6dd37b3127cce97952589e75700000010102AbOGjFq4Zsd
http://im1.shutterfly.com/procserv/47b6dd37b3127cce97953b58e78900000010102AbOGjFq4Zsd
http://im1.shutterfly.com/procserv/47b6dd37b3127cce97953b2f66ce00000010102AbOGjFq4Zsd
http://im1.shutterfly.com/procserv/47b6dd37b3127cce97953cbda7f700000010102AbOGjFq4Zsd
http://im1.shutterfly.com/procserv/47b6dd37b3127cce97953c9026ea00000010102AbOGjFq4Zsd

[Anonymous]

As regards fusing, the fuse [or breaker] should be installed in the Hot line to center rail for each power district. I personally use a fast-blow cartridge fuse on the downstream [track] side of the TPC --upon a short it blows before either my TPC or Pohos interrrupt.
[I use plain old Autolite type multi-position cartridge fuse blocks for fusing multiple power districts]
I am not familar with the Zener Diodes but assume they are to protect against current spikes. If that is the case, the diodes should be connected across-the-line [parallel] bettween the Hot and Common conductors. I think they should probably be connected across the Hot and Neutral terminals of your TPC where the PoHos connect. [anyway, unless you have cut the plugs off your PoHos, they have no raw or open terminals to connect to aside from those of the pigtail adapter's lugs on the TPC terminals] .

NOTE: any time you act to connect a train layout component [Scott's] to a household earth ground-ing conductor at a receptacle---use a $4 polarity tester to determine that in fact the earth ground is continous from the local receptacle back to the Service Panel. Not uncommon for a household ground wire to be left open at some fixture enroute back to the service panel.
Keep in mind that upon an upstream fault in the house system, where the grounding conductor is not continous back to earth, the layout becomes a part of the system---not good.

[lionelsoni]

"Ground" is only a figure of speech. The correct term is probably "common". A ground is literally connected to the earth. A common is simply a point in the circuit that is convenient for referring all the other circuit voltages to. For most three-rail train layouts, the most useful point to designate as the common is the outside rails. On a prototype electric railroad, these rails would be not only common but also grounded. This is probably why they are often loosely referred to as ground.

If you do want your rails truly grounded, you can simply connect your common to the green wire in a transformer power cord. I have done this inside the type-Z transformers that I use. The safety advantage is that any power-line voltage that might accidentally come in contact with the track will trip the circuit breaker that feeds it.

[lionelsoni]

A zener diode acts like an ordinary diode in the forward direction, but conducts at a specified voltage in the reverse direction. A simple zerner diode is not suitable for use across an AC supply. A transient voltage suppressor (TVS) is a special zener diode designed to be placed across a supply line to absorb large amounts of power for very short times. The unidirectional ones are simple zeners and are meant for use with DC. For AC you need a bidirectional TVS, which is like two zener diodes in series, but pointed in opposite directions. The voltage rating has to be higher than the peak voltage of the sinusoidal AC waveform, which is 141 percent of the nominal (root-mean-square) voltage.

[cheech]

Thanks leonard and bob. i appreciate your help.

i got how to get the fuses attached. But i still don't fully get the bi-direction diodes (TVS). Hard skulled and limited skill i guess.

They go between the PowerHouse and the TPC. To get it there i have thought of a terminal strip as a way of attaching the diodes (TVS). i would attach both Hot and Common pig tail wires from the PowerHouse to the input side of a terminal strip, attach the diode (TVS) to the output side of the Terminal strip then into the TPC.

Duz ya thinks it'll work??

[Anonymous]

The devices that need true protection from spikes are the relatively delicate electronics in the locomotives. The major power handling devices like Power Masters, TPC's and the new ZW have there own protection. If you try to use a PW power supply to feed these devices you need to install a fast acting fuse or breaker bewteen the PW device and the more modern controllers (aka TPC/PowerMaster).

Incorrect placement of a protective device can make things worse than no protection at all. A TSP "shunts" the power spike. This should in effect a "transient" short. A switching power supply may try to compensate and put out more power aggrevating the situation. Power regulating devices like TPC's/PowerMasters may be more prone to failure if a TSP is improperly installed/used.

[lionelsoni]

I don't know a powerhouse from a TPC. But the TVS should be in parallel with the track connections and any fuse or circuit breaker upstream in series.

[cheech]

thanks chuckn

your point is exactly what i am trying to overcome.

my goal is to protect the engines, the accessories and their electronics. They are modern and postwar running with powersources from both eras. maybe mixing is a basic error.

A fuse/breaker has been suggested throughout the posts in the forum for use in both Post War (ZWs) and modern power supply environments (PHs/TPCs). Frequently the TVS rears its head.

Great, but for someone like me, where/how do you put it in place is not intuitive. And they don't come with instructions.

i think with help from leonard and bob, i now know how to put the fuses in place (i.e., at the entry of power to the track system==> the how wires of track power bus, not the common).

The TVS is still mysterious. From what you describe, if used at all to control spikes, the TVS should be at the track power bus as well, but across the common and hot wires.

thank again and I do appreciate the help and the feedback.

[Anonymous]

TVS at the "lockon" is the closest you will get to a correct placement. These devices should be in the loco between the pickup rollers and common/return BEFORE the boards/circuits. A spike can come from the power supply but can also originate from devices on the layout. The TVS at the lockon protects you from spikes coming from power supplies but may not protect from a spike originating on the layout. It will eventualy quench a spike from the layout side but you don't know what it may have passed through before it got to the TVS.

[cheech]

chuckn...leonard....bob

thanks again. it will take a while for me to complete all the wiring, but i know where and how to start.

the forum has been a great help

ralph