Topics

Current Protection

Lindsay Hughes
 

Greetings

 

I am wiring a power system for my layout.  I am using a 15V 7A power supply to provide switchmode open frame power supply to provide 13.5V nominal DC power around the layout, as well as for a Digitrax DCS 240 controller.

My question is this: should I fuse the power input to the DCS-240?  I'm thinking I probably should, but I'm looking for confirmation...

Many thanks!

David McBrayer
 

YES!, you should fuse the input to the power supply.  Don’t forget to account the startup surge. 

Dave McBrayer
Castro Valley, CA 


On Nov 19, 2018, at 18:44, Lindsay Hughes
I am using a 15V 7A power supply to provide switchmode open frame power supply to provide 13.5V nominal DC power around the layout, as well as for a Digitrax DCS 240 controller.

My question is this: should I fuse the power input to the DCS-240?  


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wirefordcc
 

I want to add some clarification to this topic.  The question was whether the power input to the DCS 240 should be fused and the answer was that the input to the power supply should be fused. 

 

Yes, it is a good idea to fuse the input to the DCS 240.  The DCS 240 is a 3/5/8 amp command station/booster.  The power supply that Lindsay intends to use is a 7A supply.  So do not use the DCS240 in the 8A mode.  Use it in the 5A mode.  If in the 8A mode, the 7A supply will never be able to source enough power for the DCS 240’s internal current protection to shut it down.  A fuse on the input of the DCS 240 should be about 6A or a 5A slo-blo fuse can be used to allow the DCS 240 to do it’s thing and not require you to change the fuse 4 times during an operating session.

 

It is also a good idea to fuse the input of the power supply on the 120V AC side.  Be aware that if it is a 7A, 13.5VDC power supply on the output, the maximum input current to the supply will be less than an amp.  So using a 2A fast-blo or a  1.5A slo-blo  would be appropriate on the 120V AC side.

 

Allan Gartner  WiringForDCC.com 

        

 

Don Vollrath
 

Good advice Allan.
DonV

Charles Brumbelow
 

I have seen these recommended and even used inside Lionel ZW and KW transformers. Variable current ratings available. Charles

US Stock 10pcs 6A 30V PPTC PolySwitch Resettable Fuse Electronics, Cars, Fashion, Collectibles, Coupons and More | eBay







On Wednesday, November 21, 2018, 9:17 AM, Don Vollrath <donevol43@...> wrote:

Good advice Allan.
DonV

Carl
 

Hi Gang:

I've added these to my ZW. Much more protection than the breaker on the common wire.

https://groups.yahoo.com/neo/groups/toytrains/photos/photostream/lightbox/1508970439?orderBy=mtime&sortOrder=desc&photoFilter=ALL#zax/1508970439

Good luck, Carl.


On 11/21/2018 12:07 PM, Charles Brumbelow via Groups.Io wrote:
I have seen these recommended and even used inside Lionel ZW and KW transformers. Variable current ratings available. Charles

US Stock 10pcs 6A 30V PPTC PolySwitch Resettable Fuse Electronics, Cars, Fashion, Collectibles, Coupons and More | eBay







On Wednesday, November 21, 2018, 9:17 AM, Don Vollrath <donevol43@...> wrote:

Good advice Allan.
DonV


Virus-free. www.avast.com

 

You could also purchase my product and be able to fine tune the current setting:

http://voltscooter.com/?page_id=134

The maximum setting of my product is lower then the 6 Ampere one mentioned previously.  (the trip level of which is actually 12 Amperes).  My product is suitable for any AC circuit under 30V and will also work with DC however the wiring may need to be adjusted to make the indicator light as it has a polarity.

When using a PolySwitch type fuse you need to be aware of both the maximum voltage and the maximum current.  The maximum voltage is easy enough. 

The input voltage to the fuse should not exceed that number.  In the instance mentioned that is 30V and is just fine for Model Railroad secondary voltages but not for the primary voltages on the AC side.

Maximum current is a little harder.  Essentially the source should not be able to exceed the maximum current rating of the fuse.  I was unable to fully trace the one linked in the previous message but the maximum current of similar fuses is 40Ampere so this is certainly large enough for the purpose.