Model 344 Short Finder Kit

1. These application procedures detail the methods that should be used to perform specific types of checks on common DC track circuits and line or cable circuits. The “Other Considerations” section (Section D) at the end of this chapter provides additional information that you should keep in mind, including guidance concerning the use of the Short Finder on portions of track equipped with coded DC track circuits or audio overlay and/or motion responsive electronic track circuits.

2. You should be familiar with the proper way to use the Shortfinder in each of it’s applications before trying to identify shorted or open track circuits. Depending on your level of experience, in the beginning it would probably be best to perform the various checks listed below exactly as they are described. As you gain understanding of how the Shortfinder works you will discover ways to shorten the check procedures. After you are familiar with the following procedures, apply them at the proper point (s) when using the Guideline For Locating Shorted or Open Track Circuits (Chapter 5).

3. When looking for a short keep in mind that only a Zero (0) Ohm short will give you a 15 on the Bar Graph and 0.0 Ohms, at the short. The highest bar graph reading a one half 0hm short will give you, at the short, is approximately 11 on the bar graph and 0.5 Ohms. Always look for the highest reading on the meter, not necessarily a peak of 15 on the bar graph and 0.0 Ohms.

4. We also recommend that you try out the Short Finder to get an understanding of how it responds. It would be especially beneficial if you could introduce problems into track circuits, especially in a turnout, and observe Short Finder performance. Doing this prior to the time when a real problem requires the use of the Shortfinder will greatly enhance your ability to use it

Safety 1. As always, it is important to follow all established safety procedures. Specific safety issues to consider relative to the Shortfinder are as follows:

i. Be sure to get track time.

ii. The Shortfinder generates, one at a time, two different frequencies (3KHz and 24 KHz). If audio overlay or motion responsive track circuits are present on the track you are checking, determine which frequencies these circuits employ.

iii. The Shortfinder, under some circumstances, might activate motion responsive track circuits. Be alert to the possibility of this possibility