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PSX-AC - Intelligent Circuit Breaker for AC 2 and 3 Rail

PowerShield X | Pictures | Updated June 18, 2013

DCC Specialties applies the PSX solid state layout circuit breaker technology for AC 3 rail operators.

List: from $54.95 (see the list of dealers)

The proven solid state technology and experience that led to the development of the DCC Specialties PSX layout power district circuit breakers has been applied for AC 3 rail operations. DCC Specialties offers the PSX-AC 2 and 3 rail intelligent circuit breakers.

According to the designer Larry Maier, "the stakes are much higer with AC as operating currents can approach 20 Amps. That's enough energy to easily destroy your loco or its electronics under certain circumstances. The trick is to permit the high currents but have precise regulation that knows a destructive short from a current spike. The PSX-AC's exclusive patented microprocessor controller does the job."

There are other mechanical, non electronic circuit breakers available but they can not intelligently differentiate between a short and spike or reset automatically. The PSX-AC has automatic or manual reset feature in addition to 4 trip current settings.

Available Versions

PSX-1AC: One Output


  • All Solid State Operation
    Fast solid state design with reliable quiet action. No clicks or sparks.
  • Adaptive Load Reset
    Electronically determines if the overload is a real short or due to excess load in sound units or lighted passenger cars.
  • Block Detection
    Either a photo cell or current can be used to detect a train in a block. The photocell can turn off the block.
  • Over Voltage Protection
    If there is an over voltage on the track caused by an AC System failure or other power inputs the PSX will shut down and protect your locomotives.
  • Range of Current Trip Setting
    The currents can be adjusted over a range of 4.8 to 17.8 amps. Values can be set using jumpers.
  • Very Low Voltage Drop
    Breaker On resistance is less than 0.060 ohms, so the PSX has a low voltage drop even at high currents. Much better than detectors that use a diode voltage drop.
  • Manual or Automatic Reset
    Automatic reset of the breaker after 2 seconds. A switch can be used for a manual reset.
  • Outputs for LED Indicators
    LEDs can be added to monitor the input/output power and the status.
  • Output for Audio Alert
    An audible sounder can be added to the card to alert if there is a short.
  • No Power Supply Needed
    Board size: is 4.75 by 2.25 inches
  • Flash Programmable
    Micro Processor can accept updated software if needed.

Note: The PSX-1AC operates by opening one side of the two inputs leads when an overload is sensed.  The PSX-1AC opens the path from J1-4 to J2-2 when the breaker senses an overload. Additional power to the PSX-2AC, 3AC, & 4AC is connected by daisy chaining from J1, 1 and 2 to the next PSX J1, 3 and 4.

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