Railway switches and signals – Miscellaneous – Signals and indicators
Reexamination Certificate
2000-07-31
2002-04-09
Le, Mark T. (Department: 3617)
Railway switches and signals
Miscellaneous
Signals and indicators
C246S087000, C246S12200A, C246S47300R
Reexamination Certificate
active
06367742
ABSTRACT:
BACKGROUND OF INVENTION
This invention pertains to the field of control systems for scale model railroad layouts, and specifically to elements of the generation and distribution of track power.
Modern layout control systems allow the simultaneous control of many devices that are attached to or run on the tracks of model railroads. As the number of devices in use increases the power required to run them also increases. This leads to the requirement of more powerful boosters or power stations or other devices that deliver the power and control signals to the layout, and schemes to distribute these higher power levels.
Inherent in these boosters, power stations or power sources is the requirement that they safely deliver high power levels in an environment where the tracks may frequently sustain periods where they may be short circuited by, for example; derailed rolling stock, or wheel flanges bridging close rail gaps in the body of track turnouts or track switches.
The current art for model railroad power generation and distribution employs several power management strategies to minimize the disruption to layout operations.
In particular the boosters or other power control elements employ a control strategy to detect the overload current that occurs when the rails are short-circuited or conductively bridged. If a detected short circuit overload fault persists then the booster power output is turned off or disconnected from the tracks to ensure that an excessive amount of energy is not delivered into a fault condition.
These power management techniques do not work reliably when it is desired to parallel multiple boosters to increase available power in a sub-district of the layout. Increased power levels also require more techniques to safely handle disruptions within a sub-district.
SUMMARY OF INVENTION
The economic necessity of powering multiple track areas within a sub-section of a model railroad layout from a single power source means that interactions may occur due to activities of different items controlled within those sub-sections.
In particular, because the sub-district shares a commonality of connections to different areas of track, a short circuit fault anywhere in the sub-district will affect other track sections in that sub-district.
Additional loads within a sub-district may also require the adding of additional current capacity to increase the power available for that sub-district.
Signal cross-talk between different track areas in the same sub-district may harm other communication or control signal systems.
The power management and impedance control techniques presented in this invention solve some fundamental problems related to having multiple track sections connected in common to a single power source.
REFERENCES:
patent: 5417388 (1995-05-01), Stillwell
patent: 5451017 (1995-09-01), Graff et al.
patent: 5467946 (1995-11-01), Doehler
patent: 5752677 (1998-05-01), Rchley
patent: 6220552 (2001-04-01), Ireland
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