Lionel 135w Powerhouse & DCS

I just noticed this post (endless months of computer problems here), so I ask to be excused for delay in commenting.  However, the possiblity of costly damages resulting from transformer use in hook-ups among such equipment of mixed manufacture obliges me to comment.

I have opened one of the brick transformers some years ago (the smaller 7 amp circa 100 watt model).  The current-interrupting device inside is a small relay; my recollection is that it was a 10-A relay, made by MillionSpot (Hong Kong), a little smaller than a single dice.  This relay cannot be opened non-destructively.  The manufacturers site lists no properties in the more detailed form "make-carry-break" form at various voltages, in contrast to some other manufacturers.  This relay is opened by an external circuit, in the transformer case, in the coil leads, that operates at 7 amps more or less.  It is reported that in the larger 135-watt model, which Ed has, the relay is 15-A.

I also ran a so-called "bolted-fault" short circuit test.  This consists of shorting the output (plug, in this case) with a heavy, short wire having suitable connectors, and applying a reduced voltage to the line plug of the transformer-- special devices and instruments are required to do this and measure the result.  The 7-amp model produced 77 amps in this test, or about.  By similarity, I would estimate the 135-watt brick to be capable of about 110 amps if tested.  The UL 697 Standard, Toy Transformers, in the edition extant at the introduction of these transformers, had a special exception to the usual requirement that the interrupter device in the transformer be able by itself to interrupt any current from any connection to its terminals.  I read the actual wording of this from the Standard itself.  I would note that the manufacturers of affected equipment are normally a party to discussions with UL about each re-issue of the Standard, usually by having a voting seat on the responsible UL panel (association rep or major manufacturer rep, etc).

This explains the special output plug.  It restricts the connection of these Lionel brick transformer to certain downstream equipment capable of interrupting these large (but normally somewhat rare*) short-circuit currents.  The typical matching downstream devices are PowerMaster throttle (later versions), and New ZW, both of which are electronic devices with MOSFETs being the active device, on a timing of one cycle (1/60th second) max.  The 10-A version of the so-called "lineside shed" lock-on can also accept the special connector; this device contains a very heavy relay contact supervised by its own electronics.  Without one of these devices inline downstream, the small relay in the transformer "brick" can suffer cumulative damage to the point of burned contacts (no output at all) or welded contacts (no current interruption at all).  Examples of both conditions were reported on this board at the time of their introduction, and use by some with early TIUs.

 *(Note that the familiar "breaker test," done by bearing down across the rails with a screwdriver, can be the dreaded bolted fault; and is very destructive of breakers.  Breakers should only be tested at twice rated current, using a suitable resistor, a la the Lionel Test Bench.  The UL requirement for interrupting max rated fault current is one operation.)

The present models of TIU have fuses which will interrupt currents from the 135-watt 10-A brick.  Any early TIUs without fuses should have them added ahead of the TIU.  The fuses are the now-common automotive type with double spade lugs, and are 20-amp fuses, as I understand it.  (Some operators prefer smaller fuses as the early TIUs had smaller or thinner traces; I do not have definitive info on these.)

Modelers who exhibit in public halls often have to sign insurance agreements to use UL-labeled equipment.  It is important they realize the cutting the special output plug off this 135-watt brick transformer will void its UL-label.  Also, the instructions packed with this transformer are part of its labelling.  That means that in such situations it would be well to interpose the 10-A lineside shed lockon into any such connection to a TIU, as this larger shed has thumb-screw terminals inside to which a TIU may be attached.  I would still use fuses also at the TIU if not so fitted, although the shed relay contacts, although heavy, probably have a gravity drop-out that is sub-cycle (don't know about the electronics) as that is typical of contacts of the size I saw.

Hope this will clarify the precautions which should be taken, and the reasons why. 

I would definitely avoid the "screwdriver test" on any layout with a TUI in series with the input source (the ususal arrangement).  No protective device is truly instantaneous, and currents resulting from such tests can cumulatively loosen foil traces from the circuit boards which serve at their heat sinks.

--Frank

OK-- sorry in advance...  Ed has the smaller 7-amp or 135 watt model.  The larger is the 10-amp 180 watt model.  Comments on the shed breaker still apply, as only the 10-amp model has the thumbscrew connectors inside; it can, however, be switched to operated properly with either the 10-amp or the 7-amp brick.

Running on low sleep and don't yet know how to access the edit function.

--Frank.

I run the 180 Watt power bricks (one per channel).  These work extremely will with the TIU.

Just as an FYI, in the early days, when the TIU's did not have fuses in them, I melted one.  I was running two standard gauge passenger sets with lights and drew too much current.

I did some testing later on, and found out that the circuit breaker in one of the bricks would not "pop" under any circumstances.

The brick was replaced, the TIU was replaced with the newer version with fuses, and ammeters were installed.

I did not know about what Frank stated (above) about cutting off the plugs, at the time.  Those plugs have been gone for nine or 10 years now...