Sourcing Wayside HEP Power Systems for Rail Yards


Head End Power Unit Configurations for Passenger Trains

In the late 1990s, the American Public Transportation Association (APTA), implemented practices for Head End Power sources throughout the passenger rail industry.

According to 3.1.3 in APTA RP-R-015-99, Head End Power (HEP) is defined as “A system by which 480 VAC 3-phase electrical power, to operate auxiliaries, is provided to railroad vehicles from a central source via a trainline system. The power source can be locomotive (hence “Head End”), power car, or wayside source.”

The four source configurations for Head End Power are: alternator driven from locomotive traction prime mover, alternator driven from exclusive engine, locomotive inverter, and wayside power (stationary utility). In this post, we will only be focusing on wayside power.

A Wayside Power unit (also referred to as Yard Power Units) provides a means to temporarily plug-in power to passenger trains via HEP to a ground-based source when the locomotive engines have been shut down and/or disconnected, such as in a yard. Once connected to a wayside power unit, trains can shut off their diesel engine which reduces fuel usage and emissions.

Sourcing a Wayside Power Unit
When it comes to sourcing a wayside power unit, the control schemes can range from simple in design to rather complex. There are a wide range of features to consider for each project, such as power requirements, environmental factors, transit authority guidelines and control schemes, and code compliance from local jurisdictions.

ESL’s Wayside HEP Cabinet

To assist designers and engineers with specifying, Standard Wayside Power Cabinet specifications can be viewed here.

Unique specifications for custom Wayside Power Cabinets can also be developed by contacting ESL. We are always interested in learning more about your project requirements so we can work to provide you with the best solution possible. 

Wayside Catalog
Wayside Specifications

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