Relevance: This app note applies to the Z3
Plus, PD8 Plus module and the discontinued ZEPICIII, PD8 module.
Purpose: The purpose of this App note is to emphasize
long held rail industry best practices for installing audio overlay track
circuits. It is useful to periodically review this material to insure proper
installation and maintenance for audio overlays whether installed by railway
personnel or 3rd party contractors.
- Insure that the operating frequency
of the audio overlay is compatible with the operating frequency of all other
equipment on the same track and neighboring tracks, if applicable.
- Use properly rated primary surge
protection and ground rods. See relevant AREMA specifications.
- Periodically inspect primary surge
protection for wear due to surge activity. Reduced effectiveness of primary
protection can expose secondary protection to excessive surge levels resulting
in equipment failure.
- Use twisted # 6 bond strand for track
wires between rail connections and the overlay unit. Audio overlays are
generally used in switch unlock, DED and AEI presence detection applications.
As such, these products may be located near crossings and within signal system
circuits. If a short circuit were to occur in the track wires or surge
protection or house wiring, the signal system would be put to stop due to the
low resistance of #6 track wires, calling attention to the affected area.
- Monitoring diagnostic data provided
by DED and AEI systems will facilitate the prompt and efficient maintenance of
audio overlays.
- The product user manuals for these
products have been updated to include a simple shunt test to work hand in hand
with best practice installation methods detailed in this app note.
- Check zukinut.com often for current user manuals, installation tips and troubleshooting procedures.
