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"New Advanced" PS Power Shield Intelligent Circuit Breaker, PS Rev Intelligent Reverser / Breaker

PowerShield products have been replaced by PSX products by DCC Specialties

Tony's began development of the Power Shield concept in 1993 in response to the need of the pre-DCC command control systems like Onboard and Dynatrol. The design was modified to work with DCC and has been continually improved to make Power Shield the leader in DCC power protection and regulation. Accordingly, the new Power Shields have two new exclusive features: overvoltage protection and easy programming jumpers. Power Shield is designed by Ray Hazen of MicroDesign and manufactured by NCE Corp. PowerShield is an exclusive Tony's Train Exchange product contrary to the claims of others.

Tony’s Intelligent Breaker (PS) provides over-current and exclusive over voltage protection, which sectionalizes the connected track area and prevents shutting down other parts of your layout when the track is shorted. Not for Direct Current (DC) operation.

Tony's Intelligent Reverser (PS Rev) unit provides auto-reversing for return loops, reversing Y’s and turntables. In addition, it provides the same short circuit protection as PS. Not for Direct Current (DC) operation.

For simplicity, the layout shown has only two mainline track sections, Section 1 and Section 2. Many layouts have more than two mainline (non-reversing) track sections, each of which would be protected with a breaker. These breakers prevent shutdown of the other parts of the layout when a short occurs within one section. Note that between adjacent mainline sections, DCC1 and DCC2 must be kept on the same rail, to prevent shorting the DCC power unit (and tripping the breakers) as the train passes from one section to the next.

The layout shown also has only two reversing sections. A large layout might have more, and reversers can be added as needed. Note that the reverser provides the breaker function (to isolate faults) within its track section, as well as track reversal.

So on this example layout, a fault on any section of the layout would be isolated from all other sections. Track reversal is provided as traffic moves around the two reverse loops. All this is provided from a simple DCC power unit (needs no built-in reverse function).

The Intelligent Breaker and Reverser are solid-state, including power switching, for silent, reliable operation and long life. Both provide on-board LED indication of trip (and indication of track reversal in the case of the reverser), with provision for remote LED indication as well.

Power Shield™ Circuit Breakers/Reversers
All of us who use Command Control Systems are aware of the annoyance and damage caused by track shorts. At the least, a track short interrupts operating, at the worst, it can fry expensive power supplies or related components or hardware. Of course, track shorts multiply in conjunction with the number of operators.

If you are skeptical, here are the reasons you should use Power Shield™:

  • Enjoyable Uninterrupted Operating: This is the number one, in my opinion. Power Shield™ keeps the layout up and running for those operators who can stay on the track or avoid running against turnouts.
  • Locomotive or Electrical Accessory Protection: Power Shield™ eliminates the extremely violent voltage and current spikes caused by hard shorts that can melt wheels, accessories and destroy decoders.
  • Track Power On/Off: Power Shield can be used to manually switch track power on or off.
  • Fault Isolators: When Power Shield™ trips, you know where the problem is.
  • Booster Protection: Although these units have built in protection, the protection circuitry may eventually fail.

Why Power Shield’s are the best DCC Circuit Breaker and Reverser?

  • 5 Amp, All Scales,
  • Automatic/Manual Reset.
  • Works with Reverse Blocks.
  • Mounts at District Area
  • Easy Mount Design
  • On / Off Reverse, Status Lights
  • Buy One or More
  • Easy to Program with Jumpers
  • Solid State No Relays
  • Exclusive overvoltage protection



  • Automatic coordination with reversing units: MRC, AD520, Lenz , LK100 & Digitrax PM4
  • Automatic reclose of the breaker after 1 second (or manual re-close option)
  • LED indication of trip conditions (plus provisions for a remote LED)
  • Exclusive over voltage feature protects decoders burn out from DCC booster melt down
  • Over current trip time adjustments using jumpers
  • All solid state design, including power switching elements, for fast, reliable operation

PS Rev

  • Automatic coordination of reverse and trip functions - it’s both a reverser and a breaker
  • Automatic re-close of the breaker after 1 second (or manual re-close option)
  • Fast, quiet reversing - no blinks or clicks
  • LED indication of direction and trip conditions (plus provisions for a remote LED)
  • Exclusive over voltage feature protects decoders burn out from DCC booster melt down
  • Over current trip time adjustments using jumpers
  • All solid state design, including power switching elements, for fast, reliable operation

PS & PS Rev: User Manual


  • Input: For one PS and the PS Rev connect DCC power to DCC1 and DCC2 inputs (see below). Either DCC lead may go to either input.
  • Output: For one PS and / or PS Rev, Connect the RAIL1 and RAIL2 outputs to the isolated track section. Either RAIL output may be
    connected to either track output in the isolated section
  • Output: For more than one PS, input and output polarities must be wired the same for all power districts. For Common Rail (see above)

NOTE: PS & PSRev Are separate modules that use the same circuit board and different components. Blue shaded components represent PS assembly. Blue & Red represent PSRev assembly.

PS Rev: Initial direction - LED off, Reverse direction - LED flashing, Breaker tripped - LED on
PS: Normal, no track shorts - LED off, Track shorts, breaker tripped - LED on.


To remote the LED indicator, connect the remote LED between the XLEDA and XLEDK outputs (observe A (anode) and K (cathode) markings), and cut the foil between the two pads (on the top of the board). Both the on-board and remote LEDs will now indicate the reverser and breaker status.

Over-current Trip Time Adjustment: Allows you to maximize PS performance for your layout. Increases Sound Decoder Ops! Jumpers positions J1 and J2 can be used to adjust the over-current trip time of the breaker / reverser. (time from start of over-current until breaker will

Manual power –off :
The output track power of the breaker/reverser may be manually shut off buy connecting SWA1 to SWA2.

Manual override of automatic re-close after tripping :
Connecting a normally closed switch between the SWB1 and SWB2 will prevent automatic re-closing of the breaker/reverser. When tripped, the
breaker will not re-close until the switch is opened.

Overvoltage protection:
If overvoltage (voltage > 24 V nominal either polarity) is applied to the breaker input, the breaker and the track-connected equipment (decoders, etc.) will be protected by a clamp on the input voltage. Upstream fuses or circuit breakers must detect the fault current due to clamping, and provide fault isolation. Failure of such upstream fault isolation devices will cause (probably spectacular) failure of one or more system components.

We welcome comments or suggestions from readers; please write or call.

  Phone: 800-978-3472 or 802-878-5005.
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