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LT100 Digital Circuit Breaker
LT100 Digital Circuit Breaker
1
DIGITAL plus
Used to protect conventionally powered
layout sections on a digitally powered
layout.
Measurements approximately: 3 9/16x2
9/16x1 inch (90x65x25mm)
General specifications: Maximum voltage permitted:
18V effective Maximum current permitted:
3.5 A
When using pulse width modulated power packs, the
maximum frequency must not be higher than 150 Hz.
LT100
Digital Circuit Breaker
Art. Nr. 13 100
First edition, 01 01 2
LT100 Digital Circuit Breaker
How does the Digital Circuit Breaker
work?
Let us assume that you control a part of your model
railroad digitally and another part conventionally. For
instance you may have a digitally controlled locomotive
servicing facility and a conventionally controlled line
divided into blocks.
If you now drive a locomotive (train) from one part into
the other part, then the wheels of the vehicles will create
a connection between the 2 layout parts. This
connection will lead to a short circuit. Usually the digital
system will shut off immediately. However it is possible
for the digital and analog systems to combine in such a
way that can either damage the analog system or the
decoder. It is the task of the LT100 digital circuit
breaker module to prevent this.
The digital circuit breaker is simply inserted between
the conventional transformer (power pack) and the
track. If a connection is created by the wheels of a
vehicle, then the LT100 module will interrupt the
connection between the conventional analog system
and the track. This way a short circuit is prevented and
no damage can occur.
The track is supplied with digital voltage during this
time, so that the train can continue operating. Once the
train has completely crossed the gap and the systems
can no longer be combined the digital circuit breaker
will reconnect the analog system. This happens very
fast preventing any perceived interruption in power to
the track. The result is a smooth transition between
different control systems. LT100 Digital Circuit Breaker
3
DIGITAL plus
Both parts of the layout must be double gapped from
each other at the crossover points.
Connecting the digital circuit breaker
module
The basic connection of the digital circuit breaker
module is shown in illustration 1.
The digital circuit breaker module is simply inserted in
the supply line from your conventional power pack to the
track. In other words, you cut the connection between
power pack and track.
Connect the wires from the track with the terminals
labelled Gleis (Track) on the digital circuit breaker
module. Then connect the wires coming from the power
pack with the terminals Trafo (transformer).
Illustration 1 4
LT100 Digital Circuit Breaker
Using Pulsed Power Analog Systems
Many pulsed power analog systems can both confuse
decoders and the LT100. Locomotive with decoders
may experience erratic operation on some pulsed
power DC operation. This is evident if you find that the
locomotive has problems operating slowly in one
direction. The cure for this is to put a pair of anti parallel
capacitors on the output of the DC power pack as
shown in Figure 1. (Radio Shack, part number 272-
1022) These capacitors will smooth out the pulses from
the pulsed analog control system and allow the LT100
to work properly.
Figure 1 Anti parallel capacitors
Operation of the locomotive decoder at
change over
All Lenz Digital Plus locomotive decoders can be used
on conventional layouts with regular DC power packs. In
conventional operation a locomotive with a Digital Plus
locomotive decoder initially responds like a locomotive
without a Digital Plus locomotive decoder. If the
decoder has a built-in acceleration momentum, it will
however be active. LT100 Digital Circuit Breaker
5
DIGITAL plus
Going from digital to conventional
Going from a digital layout area into a conventional
area, the locomotive decoder will evaluate the polarity
of the conventional section. If the polarity of the section
(and the direction of travel based on this) agree with the
direction of travel in the digital section, then the
locomotive will continue on without stopping. The speed
will however depend on the voltage level in the
conventional section.
However, if the polarity does not match with the
direction of travel, then the locomotive will stop, using
the braking momentum programmed in the decoder.
Going from conventional to digital
If a locomotive goes from the conventional layout part
back into the digital part, then the built-in locomotive
decoder is again able to receive the digital information.
Just as described above, there are 2 responses
possible for the locomotive: If the direction of travel sent
from the Digital Plus command station LZ100 is the
same as the current direction of travel of the locomotive,
then the locomotive also receives the transmitted speed
data. The locomotive thus continues to travel.
If the actual direction of travel is not the same as the one
transmitted by the command station, then the
locomotive will stop using the programmed braking
momentum.
The responses listed here can be put to use in the
operation of a layout: 6
LT100 Digital Circuit Breaker
Tips for use
Following you will find two examples for useful
applications for LT100
Interchange track
If several conventional locomotives are to be operating
in the same power circuit in your conventional layout
part, then it is recommended to use an interchange
track. This track must be long enough for the longest
train operating across it to completely fit onto it.
Using this track prevents digital voltage from entering
the conventional area during the time that the
conventional area is connected to the digital area by the
vehicle wheels.
The wiring for such an interchange track is shown in
illustration 2.
Braking at signals
The fact that the locomotive decoder will either brake or
not when changing from digital to conventional,
Illustration 2 LT100 Digital Circuit Breaker
7
DIGITAL plus
depending on the polarity, as described earlier, can be
used to accomplish automatic braking in front of a
signal.
Install a double gapped (both rails) braking section in
front of the signal. In illustration 3 this area is shown in
gray highlighting. The length of this section is
determined by the braking momentum programmed in
the locomotive decoder. The section must be long
enough for the locomotive to come to a complete stop
inside the section.
Make the power supply for such a section switchable
with a double pole switch (or relay), to alter between
supply from the digital and the conventional power pack
(as drawn).
Set the conventional power pack for a maximum
voltage. Set the polarity such that in the direction of
travel shown, the left rail is plus.
The double pole switch should supply the braking area
with conventional DC power when the signal shows
red, and when it shows green supply it digitally. This
can be accomplished by using the contacts on a
commonly available twin-coil model railroad relay, that
is controlled together with the signal.
If the locomotive now enters this section, and the signal
shows red, then the polarity and the direction of travel
determined by it, do not agree with the digital direction
of travel . The locomotive will thus stop using the
programmed braking momentum. If the signal is set to
green again, then the switch will again supply the
braking section from the digital part of the layout.
Through this the locomotive receives its speed
commands again, and starts up with the programmed
acceleration momentum. This page is intentionally left
blank. 8
LT100 Digital Circuit Breaker
Not suited for children under 3 years of age because of small parts that may
be swallowed. If used carelessly, injury may result due to functionally
required sharp edges and points! Only for dry rooms. Reservation for error,
as well as for changes due to technical improvements, product development
or other production methods. Any responsibility for damage or incidental
damages due to non-intended use, non-compliance with this manual,
operation with transformers not certified for model railroads, altered or
damaged transformers, or other electrical devices, unauthorized changes,
acts of violence, overheating, moisture damage, etc. is excluded; this also
voids the warranty.
Hüttenbergstraße 29
35398 Gießen,
Germany
Hotline: 06403 900 133
Fax: 06403 5332
http://www.lenz.com
Lenz Agency of North
America
PO Box 143
Chelmsford, MA 01824
ph/fax: 978 250 1494
support@lenz.com
This equipment complies with Part 15 of FCC Rules. Operation is subject to the
following two conditions: (1) this device may not cause harmful interference,
and (2) this device must accept any interference received, including
interference that may cause undesired operation.
Please save this manual for future reference!
© 1998 Lenz GmbH, All Rights Reserved