Associated Products:

DCS240, PS2012, PS514

KB1046: Powering the DCS240

This article was last updated on Nov. 3, 2016, 11:02 a.m. | Print Article | Leave Feedback

The PS514 is the Digitrax recommended power supply for the DCS240 in 5 amp mode.  For operations at 8 amps the PS2012 is the recommended power supply. When using the PS2012 special wiring considerations need to be used when powering both the DCS240 and legacy boosters from the same PS2012.  Please see the separate article “Powering your DCS240 with a PS2012” and the additional notes below.

The DCS240 may be powered either using the barrel plug connector or the screw terminals labeled “+” and “- “. The barrel plug connector is only rated for a maximum of 5 amps.  A DC supply providing more than 5 amps can be used, however when the barrel plug connector is engaged the DCS240 will limit the current draw to 5 amps. The screw terminals can be used with any suitable DC power supply up to the unit’s maximum 8 amps.  Using the screw terminals will set the DCS240s current maximum draw at 8 amps. Make sure your DC power supply is rated for your desired voltage and amperage. When using the screw terminals make sure that the polarity of the power supply matches the correct terminals on the connector. The DCS240 is reverse input protected, however it will not power on if the DC polarity is incorrect.

The DCS240 is for use with DC POWER input ONLY, MAXIMUM INPUT 8 AMPS, 24VDC, 192 VA MAXIMUM CONTINUOUS, DO NOT Exceed 25VDC maximum Input. Minimum Input 13VDC.

It is recommended that a filtered regulated DC power pack be used to power the DCS240.  A transformer and bridge rectifier can be used however any power irregularities will be passed along to the track and could cause undesirable effects. 

If you plan on using your DCS240 as a command station ONLY and not using the booster or track outputs, the unit will operate on a minimum of 1.2 amps.    

There are many power supplies and power packs that can supply the input power for the DCS240. Most regular DC model railroad power packs are not able to supply sufficient amperage to the DCS240, because they were designed to run only 1 or 2 locomotives in a DC blocked system. With Complete Train Control you’ll be running multiple locomotives in the same power district so, you’ll need to provide more power to each district.

It is recommended that when selecting a DC power supply the voltage should slightly exceed the track voltage you plan to run your layout at. However, the DC input voltage should not exceed track voltage by more than 3V. If the DC supply voltage exceeds track voltage by more than approximately 3V the DCS240 will enter Safe Operation Mode and proportionally limit the available amperage to run your layout.  Track voltage can be trimmed to match your DC power supply’s outputs, however be sure your track voltage does not exceed the operational voltage of your Locomotives as damage may occur.

Using the PS2012:  The 2016 US DOE external power supply Efficiency requirements effectively require using DC input power and supplies for new-design or Advanced Command Stations/Boosters like the DCS240.  When sharing a suitable DC supply for an Advanced type unit like a DCS240 with Legacy Command Stations/Boosters designed to run on AC output transformers special wiring considerations must be made. This is because the common Booster Ground (typically pin 4’s) and negative power return wires have a diode offset in legacy (AC input) units that will cause an Advanced Booster to effectively carry all the return currents to any common power supply and possibly overload connectors in high load and/or fault conditions.  It is not recommended that Advanced and Legacy Boosters share the same PS2012 power supply, however following the wiring diagram and instructions below can mitigate the risk of overload.

 

 

The Diagram notes a number of important points to ensure a safe and reliable installation.  The PS2012 output current capacity exceeds most Boosters’, so each of the positive leads must employ a CPD, or Current Protection Device, such as; a fuse, polyfuse Y-cable  or circuit breaker of a rating matching the unit, to protect the wiring and all devices from potential fault currents.

The wiring diagram assumes that all the Booster grounds shown on the track/power connector pin 4 only return with suitably sized wires back to the PS2012 negative terminals.

The PS2012 DC positive (after the CPD) is connected via pin 7 on all the connectors. To lower the DCS240 from 8A to 5A rating for; smaller layouts, shorter wiring and/or more delicate rolling stock, feed the e.g. DCS240 positive wire into the center of a 2.1mm barrel connector in the 5A jack as shown by the dashed line, instead of pin 7.

The required track wiring is not shown, but should also be sized as recommended for the Booster capacity (typically busses of 12AWG at 8A rating up to ~30’ runs, and multiple feeders at ~ 18 - 22AWG to each rail section) so when a rail section furthest from the Booster is shorted, the Booster reliably sees the short circuit.

The PS2102 can be set to 3 different output voltages, and the N-scale setting at 13.8V DC output provides the highest current capability of 20 amps.  If you wish lowest unit heat-stress and maximum number of Boosters per PS2012, the N setting is the best to use.  Since most HO locomotives are rated for 12V maximum sustained rail voltage, the PS2012 N-scale setting is also strongly recommended for HO layouts.

The number of Boosters connected should roughly match the PS2012 capacity.  In most cases not all Boosters will be carrying maximum load capacity at the same time, so the PS2012 is unlikely to safety-shutdown for Overcurrent or Thermal Overload.

Additionally, if you want to run your layout at higher voltages there is a slight mismatch with the factory default voltages in the DCS240 and the PS2012.  You will be required to adjust the voltage trim settings in the DCS240 to get the full amperage output.  When the input voltage exceeds track voltage by approximately 3v, the DCS240 will go into Safe Operation mode and limit the available amperage.  A shown by the default voltages below the DCS240 is most likely to go into Safe Operations mode when set in the HO setting.  

The DCS240 default nominal voltage settings are:

N Scale: 12.4v             HO Scale: 14.7v          O/G Scale: 20.4v

The voltage outputs for the PS2012 are:

N Scale: 13.8v             HO Scale: 18v             O/G Scale: 23v

Depending on the variation in the unit the DCS240 will not always go into Safe Operation mode when in this configuration.  When powering your DCS240 with a PS2012 be sure that the unit has not gone into Safe Operation mode.  Look for the PWR indicator to wink OFF twice, this indicates the DCS240 is in Safe Operation mode and you will need to trim the track voltage up to have full access to the 8 amps.  Input voltage should not exceed track voltage by more than approximately 3v to avoid putting the unit into safe operation mode.  When using the PS2012 and default voltages the HO settings are most likely to cause the DCS240 to go into safe operation mode.   Be sure that you do not set your track voltage above what your locomotives are rated for.

 

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