Postwar ZW Circuit Breaker

Unfortunately, you heard wrong.

There is NO circuit breaker fast enough to protect the electronics. What you want to do is search the now voluminous subject matter on this in the forum to provide you with the answers on Transient Voltage Suppression, and as an ancillary subject, using separate external circuit breakers on the outputs of your ZW for transformer and wiring protection(the breaker are not for, and never were for, protecting the trains).

what acdxrob said !!  also , = mouser.com    655-w28-xq1a-3   or dash 5 or 7  or 10.  its what many of us use and they trip quick.   many posts  re: breakers on this  forum if you search a bit.

gandydancer,

    Here is how you want to run to protect your layout including all the newer engines & rolling stock.  1st use the DCS system, place 5-7 or 10 Amps Breakers between your Transformers & your TIU on the red middle hot wire, I use the original Scott type resettables available from train electrics one of the OGR Sponsors, Hennings one of our other OGR forum sponsors also has the 5 Amp auto resettable breakers, which are very nice.

The TVS in the DCS TIU will protect your modern engines, the Breakers will protect your TIU and the rest of your layout.  Running in this manner protects your layout, especially when using old Lionel ZW & KW transformers.

Have fun with your layout.

PCRR/Dave

Note the Scott type Resettable Breaker Bank setting along side the old KW & running between all the different transformers, including the modern Z4K and the DCS TIU.  Running in this manner I have never damaged any part of my layout including all modern engines & DCS TIU's.

Thanks ADCX Rob I got the TVS diode part understood. I am going to order 1.5K36CA TVS's from Digikey. Now on to the circuit breaker or fuses. My question to you is this. I was told that I could use some sort of in-line fuses that could be bought at the auto parts store. Is this correct? If so do you have any recomendations? Will 8amp be sufficient? I'm really lost. I want to use fuses. Do you happen to know if Digikey has what I'm looking for?

Circuit breakers are for protecting the transformer and wiring to the track from an overcurrent situation, nothing more and nothing less. They do not protect from transient voltage spikes; that is what TVS devices are for.

If a circuit board fails due to a defective component and starts to smoke, depending on the failure, it may not draw sufficient current to trip any circuit breaker. Neither the fastest circuit breaker or any TVS device will protect the electronics in this scenario.

A transient voltage spike may be produced upon the initial powering up of the track,  a sudden loss of voltage caused by a circuit breaker tripping during a derailment, and also the spike caused when the circuit breaker closes again.

A short circuit will not damage the electronics, but the transient voltage spike may do so; this is where the TVS diodes would protect the electronics.

No transient voltage spike will ever trip a circuit breaker or blow a fuse, as they are designed to protect against over-current conditions, not over-voltage conditions.

Layouts that run older trains without electronics do not need TVS diodes, as there is nothing to protect. A good, fast acting circuit breaker is needed in all layouts, regardless of the vintage of trains running.

Larry

No, no idea. I don't use fuses.

Sounds like a lot of hi-tech mumbo jumbo to protect against something that might happen once in a million times.  I have been using an old ZW for over 10 years to run my DCS and TMCC layout with fuses as protection and blown them several times with no damage to anything on the layout.

Methinks you guys worry too much.

.....

Dennis

Dennis,

    Fast Blowing fuses or Scott Type Breakers with a DCS works just fine, we have both run in a similar manner for many many years with zero problems or damage.  The fuses or breakers work well and the DCS has a built in TVS, nothing else is really required.

PCRR/Dave

ive replaced postwar breakers with breakers from radio shack

Pine Creek, the thing that is saving your electronics is the TVS, not the breakers or fuses.

Speed has nothing to do with it. Fuses and breakers are for limiting current only, and will not provide any protection against over voltage transient spikes.

Just put 10 AMP quick blow fuses in line between your track and the Z. Always worked on my layout. The internal circuit breakers were intended to protect the transformers, not the trains. 

Gandy

There's no differentiation between internal and external breakers/fuses and their function, they both protect the wiring and transformer. Neither protects the trains from over voltage transient spikes.

And why use consumable fuses?

Rob, Speed has everything to do with protecting electronics from transient spikes.  That's why TVS devices were invented.  Breakers and fuses are way too slow to protect electronics from fast transients.

Servoguy,

If a circuit breaker or fuse could be designed to operate as fast as a TVS diode, could it be used to suppress a transient voltage, and how would it do so?

Larry

You're confusing current with voltage. 

Breakers and fuses of any speed cannot protect electronics from fast(or slow, for that matter) transient(or otherwise) spikes.  A steady .1ma at 1000v will never blow a 5 amp fuse or breaker.

If a circuit breaker or fuse could be designed to operate as fast as a TVS diode, could it be used to suppress a transient voltage, and how would it do so?

"If a circuit breaker or fuse could be designed to operate as fast as a TVS diode, could it be used to suppress a transient voltage, and how would it do so?"

This is an academic question, and the answer is it cannot be done so why waste time talking about it.  

Servoguy, here are 2 of your quotes from your posts on this thread:

"Circuit breakers are too slow to protect electronics from transient spikes.  Ditto fuses".

"Breakers and fuses are way too slow to protect electronics from fast transients".

The "academic" question was asked because your posts seem to imply that fast acting circuit breakers and fuses would protect against transient voltage spikes, and that present circuit breakers and fuses will not.

It seems that your statements are misunderstood by other members of this forum and need clarification.

Larry

Hey, I disagree with Servoguy plenty, but come on.

Let not beat a dead horse.

                   Bless You!!  

"Pappy"