FIELD OF THE INVENTION
The present invention relates to the field of electrical powered railway vehicles,
and more particularly to electrical junction boxes for electrical railway vehicles
that are operative for isolating power to an onboard power collector device when
the railway vehicle is connected to a removable shore power source in the
maintenance facility.
BACKGROUND OF THE INVENTION
Many electric railway vehicles receive power from a track-based power system
as they travel over a railway track. Shown in Figure 1 is a non-limiting example of
a monorail railway track 2 that comprises two running rails 6 and a LIM reaction
rail 8. Included on the right side of the railway track 2 is a power rail 12 for
providing power to a railway vehicle that travels over the railway track 2.
In order to receive power from the power rail 12 during travel over the railway
track 2, the railway vehicle includes at least one onboard power collector device
that is able to interface with the power rail 12 for receiving power. The power that
is received from the onboard power collector devices enters an onboard electrical
junction box, which then supplies the power to one or more electrical systems of
the railway vehicle.
When a railway vehicle enters a maintenance area or storage area, the power
rail 12 that is located along the track is no longer available to supply power to the
railway vehicle. As such, most maintenance areas comprise a local shore power
source (generally in the form of a cable called a "stinger") that can be connected
2
•
to the railway vehicle for providing power to the railway vehicle during
maintenance or diagnostic procedures.
A deficiency with existing railway vehicles is that the onboard power collector
devices that receive power from the power rail 12 are exposed to the
environment when in the maintenance area. As such, when the local shore
power source is connected to the railway vehicle, these onboard power collector
devices present live exposed ends of a power source. This is very dangerous for
workers within the maintenance area, who may accidentally come into contact
with the exposed power collector devices and suffer from electrical shock. In
• some circumstances, when the railway vehicle is in the maintenance area,
covers are placed over the power collector device that include warning signs
thereon, in order to help maintenance workers from coming into contact with their
exposed surfaces. However, despite this precaution, it has been found that
accidents still happen and workers sometimes are badly hurt by high-voltage
electrical shocks.
In light of the above, it can be seen that there is a need in the industry for an
improved railway vehicle power supply system that has improved safety so as to
improve on the overall operation of the electrical powered railway vehicles.
e SUMMARY OF THE INVENTION
In accordance with a first broad aspect, the present invention provides an
onboard electrical junction box for supplying power to an electrical system of a
vehicle. The onboard electrical junction box comprises an auto-change-over
switch adapted to acquire: a first state wherein power is supplied to the electrical
system from a power rail via at least one onboard power collector device; and a
second state wherein power is supplied to the electrical system from a removable
3
shore power source, wherein during operation in the second state, the at least
one onboard power collector device is isolated from the power supplied by the
removable shore power source. The onboard electrical junction box also
comprises a switch control module in electrical communication with the autochange-
over switch for causing the auto-change-over switch to acquire the
second state upon detection that: the removable shore power source has
established an electrical connection with the onboard electrical junction box; and
the electrical system of the vehicle is receiving power below a predetermined
threshold.
e In accordance with a second broad aspect, the present invention provides a
method for supplying power to an electrical system of a railway vehicle through
an onboard electrical junction box. The onboard electrical junction box is capable
of supplying power to the electrical system of the railway vehicle from a power
rail via at least one onboard power collector device, and from a removable shore
power source. The method comprises detecting when: an electrical connection
between the removable shore power source and the onboard electrical junction
box has been established; and the electrical system of the vehicle is not
receiving power from either the at least one onboard power collector device or
the removable shore power source. The method also comprises, upon detection
of items (1) and (2): causing power from the removable shore power source to be e supplied to the electrical system of the vehicle; and causing the power from the
removable shore power source to be isolated from the at least one onboard
power collector device.
In accordance with a third broad aspect, the present invention provides a system
for providing power to an electrical system of a railway vehicle. The system
comprises at least one onboard power collector device for collecting power from
a power rail. The system also comprises an onboard electrical junction box in
4
electrical communication with the at least one onboard power collector device.
The onboard electrical junction box comprises an auto-change-over switch
adapted to acquire: a first state wherein power is supplied to the electrical system
from the power rail via the at least one onboard power collector device; and a
second state wherein power is supplied to the electrical system from a removable
shore power source, wherein during operation in the second state, the at least
one onboard power collector device is isolated from the power supplied by the
removable shore power source. The onboard electrical junction box also
comprises a switch control module in electrical communication with the autochange-
over switch for causing the auto change-over switch to acquire the
t) second state upon detection that: the removable shore power source has
established an electrical connection with the onboard electrical junction box; and
the electrical system of the vehicle is receiving power below a predetermined
threshold.
These and other aspects and features of the present invention will now become
apparent to those of ordinary skill in the art upon review of the following
description of specific embodiments of the invention and the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
Figure 1 shows a non-limiting example of a railway track comprising a power-rail
assembly for providing power to an electric railway vehicle during travel over the
railway track;
5
Figure 2 shows an isometric view of an electrical junction box in accordance with
a non-limiting example of implementation of the present invention;
Figure 3 shows a non-limiting functional block diagram of a railway vehicle
comprising the electrical junction box of Figure 2;
Figure 4 shows a non-limiting schematic diagram of the functional elements of
the electrical junction box of Figure 2;
Figure 5 shows a first non-limiting flow diagram of an operation performed by a
switch control module according to the present invention;
Figure 6 shows a second non-limiting flow diagram of an operation performed by
the switch control module according to the present invention; and
Figure 7 shows a non-limiting flow diagram of a method executed by the switch
control module according to the present invention.
Other aspects and features of the present invention will become apparent to
those ordinarily skilled in the art upon review of the following description of
specific embodiments of the invention in conjunction with the accompanying
~ figures.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Shown in Figure 2 is a non-limiting isometric view of an onboard electrical
junction box 20 according to the present invention. The electrical junction box 20
is located onboard a railway vehicle 24 and is operative for supplying power to
one or more electrical systems 26 of the railway vehicle 24, such as the vehicle's
6
auxiliary power unit (APU) 28 and the vehicle's propulsion control system (peS)
30, among other possibilities.
When the railway vehicle 24 is traveling over a railway track, the electrical
junction box 20 is operative for receiving power from a track-based power rail
(such as the power rail 12 shown in Figure 1) via at least one onboard power
collector device 36 (sometimes referred to as a "collector shoe"). Then, when the
railway vehicle 24 is within a maintenance area, the electrical junction box 20 is
operative for receiving power from a removable shore power source 32
(sometimes referred to as a "stinger") that is located within the maintenance
area. As shown, the electrical junction box 20 comprises connector elements 22
(as shown in Figure 2) for connecting the electrical junction box 20 to the
electrical systems of the railway vehicle 24, as well as to the power collector
device 36 and the removable shore power source 32. Through these
connections, the electrical junction box 20 is able to receive power from a power
source (either the track-based power rail 12 or the removable shore power
source 32), and supply that power to at least one electrical system of the railway
vehicle 24.
As will be described in more detail below, when the railway vehicle 24 is moved
into a maintenance area, the electrical junction box 20 is operative for
C automatically detecting that the removable shore power source 32 has been
connected to the onboard electrical junction box 20, and under the right
circumstances, is able to supply power from the removable shore power source
32 to at least one electrical system of the railway vehicle 24, while
simultaneously isolating the onboard power collector device 36 from the
removable shore power source 32. As such, when the railway veh~c1e 24 is in the
maintenance area, the onboard power collector device 36 does not present a live
electrical surface that can be a safety hazard to the maintenance workers.
7
'-
Shown in Figure 3 is a non-limiting functional block diagram of a railway vehicle
24 comprising the onboard electrical junction box 20 as described above. The
railway vehicle 24 may be any type of railway vehicle that is capable of receiving
electrical power. For example, the railway vehicle 24 may be an electrical
monorail vehicle, an automatic people mover (APM), such as at an airport, or an
electrical sub-way vehicle, among other possibilities.
As shown, the railway vehicle 24 comprises electrical systems 26 that provide
electricity to the various components of the railway vehicle 24 for allowing the
railway vehicle 24 to operate. In the non-limiting block diagram shown, the
railway vehicle 24 comprises two electrical systems 26; namely an APU 28 and a
pes 30. Although only two electrical systems 26 are shown, it should be
appreciated that the railway vehicle 24 may comprise any number of different
electrical systems that require power from a power source. The onboard
electrical junction box 20 is in communication with the electrical systems 26 for
supplying power thereto. In accordance with a non-limiting embodiment, the
onboard electrical junction box 20 is a high voltage junction box that is able to
supply 750V to the electrical systems 26. For the purposes of the present
description, the onboard electrical junction box 20 will be described as supplying
power to the electrical systems 26 (namely the APU 28 and the pes 30).
However, it should be understood that the onboard electrical junction box 20 may
supply power to only one electrical system (such as the APU 28, for example), or
the onboard electrical junction box 20 may supply power to any number of the
electrical systems in the case where the railway vehicle 24 comprises multiple
different electrical systems 26.
In order to be able to supply power to the electrical systems 26, the onboard
electrical junction box 20 is capable of receiving power from two different
8
electrical power sources; namely from the track based power rail 12 via an
onboard power collector device 36, and from the removable shore power source
32. As described above, the onboard electrical junction box 20 typically receives
power from the track-based power rail 12 when the railway vehicle 24 is travelling
over the railway track, and typically receives power from the removable shore
power source 32 when the railway vehicle 24 is within a maintenance area. In
general, each of these power sources is in electrical communication with the
onboard electrical junction box 20 at different times. However, it is possible that
the removable shore power source 32 could be connected to the onboard
electrical junction box 20 while the onboard electrical junction box 20 is still e receiving power from the track based power rail 12. As such, the onboard
electrical junction box 20 according to the present invention is equipped with
safety mechanisms and functionality to avoid accidents that can arise from
receiving power from two different power sources at the same time. This will be
described in more detail below.
As shown in Figure 3, the onboard electrical junction box 20 comprises connector
element 22a to which the removable shore power source 32 can be connected,
and connector element 22b to which the onboard power collector device 36 is
connected. The onboard power collector device 36 generally stays connected to
the onboard electrical junction box 20 at all times, even when the removable
shore power source 32 is connected. Although only one power collector device
36 is shown in the block diagram of Figure 3, it is to be understood that the
railway vehicle 24 may comprise two or more power collector devices 36, which
would all be in electrical communication with the onboard electrical junction box
20. Furthermore, in accordance with a non-limiting embodiment, the onboard
power collector device 36 is a current collector device.
9
The onboard electrical junction box 20 further comprises an auto-change-over
switch 34 that is in communication with both the connector elements 22a and
22b. The auto-change-over switch 34 is operative for switching between the
track-based power rail 12 and the removable shore power source 32 for
providing power to the electrical systems 26. More specifically, the auto-changeover
switch 34 is operative for acquiring: (i) a first state wherein power is supplied
to the electrical systems 26 from the track based power rail 12, via the onboard
power collector device 36; and (ii) a second state, wherein the power is supplied
to the electrical systems 26 from the removable shore power source 32.
Furthermore, when the auto-change-over switch 34 is in the second state, the
auto-change-over switch 34 causes the power collector device 36 to be isolated
from the power supplied by the removable shore power source 32. In this
manner, when the railway vehicle 24 is in a maintenance area, and is being
supplied with power from the removable shore power source 32 (such as a
"stinger" cable), maintenance workers are not in danger of being electrically
shocked by accidental contact with the onboard power collector device 36 (which
could be a "collector shoe").
The switching of the auto-change-over switch 34 between the first state and the
second state is controlled by a switch control module 38 at least in part on a e basis of control signals received from the removable shore power source 32
when it is connected to the onboard electrical junction box 20 and a load sensor
module 40 that is operative for detecting when an electrical load is being supplied
to the electrical systems 26.
The functioning of the onboard electrical junction box 20, and specifically the
auto-change-over switch 34, will now be described in more detail with respect to
the schematic diagram of Figure 4 and the flow diagrams of Figures 5 through 7.
10
Figure 4 shows a non-limiting schematic diagram of the onboard electrical
junction box 20 with the removable shore power source 32 connected thereto. In
the non-limiting embodiment shown, the auto-change-over switch 34 is a three
pole motorized change-over switch. It should, however, be appreciated that other
types of switches could also be used without departing from the present
invention. The motorized change-over switch is able to change position (from the
first state to the second state, or vice versa) based on detection at the switch
control module 38 of certain circumstances, which will be discussed in more
detail below with respect to specific examples. As shown, the switch control
module 38 comprises a spring return three position control switch 42 that is able
to switch between a power collector device position (represented by junction 42a42a),
a removable shore power source position (represented by junction 42b42b)
and a 0 position. Both the three pole motorized change-over switch and the
spring return three position control switch 42 are solid state switches. In general,
solid state switches are lighter, more reliable and less expensive than traditional
electro-mechanical devices.
Switching from receiving power from the onboard power collector device
36 to receiving power from the removable shore power source 32
I' Let us now consider the functioning of the onb6ard electrical junction box 20
when the railway vehicle 24 moves into a maintenance area where there is no
longer a track-based power rail 12. When the railway vehicle 24 enters the
maintenance area, the auto-change-over switch 34 will be in the first state,
wherein it allows power to be supplied to the electrical systems 26 (the APU 28
and pes 30) from the track-based power rail 12, via the onboard power collector
device 36. When the auto-change-over switch 34 is in the first state, the three
poles 11-21, 31-41 and 51-61 are closed so that power can flow from the onboard
11
power collector device 36 to the electrical systems 26 of the railway vehicle 24.
Furthermore, the three poles 111-211, 311-411 and 511-611 are open so that no power
from the removable shore power source 32 can get through to the electrical
systems 26.
Typically, once the railway vehicle 24 is in the maintenance area, a certain
amount of time (such as 15 minutes, for example) is allowed to elapse before the
removable shore power source 32 is connected to the onboard electrical junction
box 20. This time allows the electrical load that was being received from the
onboard power collector device 36 to discharge, such that the auto-change-over
switch 34 is not caused to change position while the electrical systems 26 of the
railway vehicle 24 are under load.
As shown, the onboard electrical junction box 20 comprises the load sensor
module 40 that is able to detect whether the electrical systems 26 are under
electrical load. In accordance with a non-limiting embodiment, the load sensor
module 40 is a current sensor module 41 that detects when the current flowing to
the electrical systems 26 is below a certain threshold. However, in an alternative
embodiment, the load sensor module 40 could also be a voltage sensor module.
Any device capable of detecting when load is being supplied to the electrical
systems 26 is included within the scope of the present invention.
The purpose of the load sensor module 40 (which in the embodiment shown in
Figure 4 is the current sensor module 41), is to ensure that the auto-change-over
switch 34 is unable to change position (Le., from the first state to the second
state, or vice versa) when the vehicle's electrical systems 26 are under load. As
such, until the current sensor module 41 has detected that the current being
supplied to the electrical systems 26 is below a certain threshold (such as 1A, for
example), the auto-change-over switch 34 is prevented from changing position.
12
Once the designated time period (such as 15 minutes) has elapsed, such that the
power to the electrical systems 26 has presumably discharged, the removable
shore power source 32 can then be connected to the onboard electrical junction
box 20. Figure 4 shows the removable shore power source 32 connected to the
onboard electrical junction box 20.
In order for the switch control module 38 to cause the auto-change-over switch
34 to change position such that power is supplied to the electrical systems 26 via
the removable shore power source 32, two things must be detected. Firstly, it
must be detected that the electrical load being supplied to the electrical systems
26 is below a certain threshold, such that the auto-change-over switch 34 does
not change position while the electrical systems 26 are under load. And
secondly, it must be detected that the removable shore power source 32 is in
electrical connection with the onboard electrical junction box 20. These two
conditions will be described in more detail below with respect to the flow chart
shown in Figure 5.
More specifically, Figure 5 shows a flow diagram of the process that occurs at
the switch control module 38 in order to cause the auto-change-over switch 34 to
switch from the first state to the second state. At step 50, the switch control e module 38 needs to detect whether the load being supplied to the vehicle's
electrical systems 26 is below a certain threshold. As mentioned above, if the
load is not below the certain threshold, then the auto-change-over switch 34 will
be prevented from changing position for safety reasons. This is represented by
box 52 of Figure 5.
Referring back to Figure 4, the detection of whether a load on the electrical
systems 26 is below a certain threshold is performed on a basis of a signal from
13
the current sensor module 41. When the current sensor module 41 detects that
the current being supplied to the electrical systems 26 is below a certain
threshold (such as 1A), then it moves from the normally open position (NO) to the
closed position (NC), as shown. When the current sensor module 41 is in the
closed position, a signal is able to pass to the switch control module 38, such that
the switch control module 38 is able to detect that the load on the electrical
systems 26 is below the certain threshold. However, when the current sensor
module 41 is in the open position, it means that a load is being applied to the
electrical systems 26, and no signal from the current sensor module 41 is
received at the switch control module 38. In the absence of such a signal, the
switch control module 38 is prevented from causing the auto-change-over switch
34 from changing position. Again, this is represented by box 52 of Figure 5.
In accordance with a non-limiting embodiment, as shown in Figure 4, when the
load on the electrical systems 26 is below a certain threshold, the signal from the
current sensor module 41 to the switch control module 38 is received at a time
delay relay 44. The time delay relay 44 ensures that the load on the vehicle's
electrical systems 26 has been below the certain threshold for at least a
predetermined period of time (such as 120 seconds, for example) prior to
enabling the switch control module 38 to allow the auto-change-over switch 34 to
switch position. When the time delay relay 44 has detected that the signal from
the current sensor module41 has been received at the switch control module 38
for the predetermined period of time, then a relay KT2 is closed. By closing the
relay, the switch control module 38 is no longer prevented from causing the auto
change-over switch from changing position.
In addition to detecting that the load on the electrical systems 26 is below a
certain threshold, in order to be able to cause the auto-change-over switch 34 to
change from the first state to the second state, at step 54 of Figure 5, the switch
14
control module 38 needs to detect that the removable shore power source 32 has
been connected to the onboard electrical junction box 20, and as such is
available to supply power to the vehicle's electrical systems 26. In the
embodiment shown in Figure 4, the removable shore power source 32 has been
connected to the onboard electrical junction box 20. The removable shore power
source 32 comprises both a 24VDC circuit and a 750VDC circuit. The 750VDC
circuit is intended to provide high voltage power to the electrical systems 26 of
the railway vehicle 24, and the 24VDC circuit is a control circuit for enabling the
switch control module 38 to detect when the removable shore power source 32
has been connected to the onboard electrical junction box 20.
More specifically, when the removable shore power source 32 has been
connected to the onboard electrical junction box 20, a low voltage (24V) control
signal from the 24VDC circuit passes through connector pins Band H, and
travels to the switch control module 38. Upon receipt of this 24V control signal,
the switch control module detects that the removable shore power source 32 has
been connected to the onboard electrical junction box 20. Upon this detection,
the power collector device position 42a-42a of the control switch 42 is opened,
and the removable shore power source position 42b-42b is closed. It should be
appreciated that this movement of the control switch 42 is only possible when the
current sensor module 41 has provided a signal indicative that the current
applied to the electrical systems 26 of the railway vehicle 24 is below a certain
threshold (meaning that no load is being applied to the railway vehicle 24).
Otherwise, in the absence of such a signal from the current sensor module 41,
the control switch 42 is prevented from being moved, regardless of whether the
24V control signal is received at the switch control module 38.
Furthermore, if the presence of the removable shore power source 32 is not
detected by the switch control module 38, regardless of whether the load being
15
supplied to the electrical systems 26 is below the certain threshold, the autochange-
over switch 34 will not be permitted to change position. This is
represented by box 56 of Figure 5.
Although in Figure 5 step 50 is shown prior to step 54, it should be appreciated
that these two steps could have been shown in the reverse order, with step 54
shown prior to step 50.
Assuming that the load to the electrical systems 26 of the railway vehicle 24 is
below a certain threshold, and the switch control module 38 has detected that the
removable shore power source 32 has been connected to the onboard electrical
junction box 20, at step 58 shown in Figure 5, the switch control module 38
causes the auto-change-over switch 34 to change position such that power is
supplied to the electrical systems 26 of the railway vehicle 24 by the 750VDC
circuit of the removable shore power source 32. More specifically, upon closing
of the removable shore power source position 42b-42b of the control switch 42,
the auto-change-over switch 34 is automatically activated so as to change
position to the second state. In addition, included within the onboard electrical
junction box 20 is an indicator light 46 that is automatically illuminated upon
closing of the removable shore power source position 42b-42b of the control
switch 42, such that a visual indication is provided to an operator that the autochange-
over switch 34 is now in a position wherein power is being supplied to
the electrical systems 26 via the removable shore power source 32.
When the auto-change-over switch 34 has switched to the second state, the
three poles 111-211, 311-411 and 511-611 are closed so that power can flow from the
removable shore power source 32 to the electrical systems 26 of the railway
vehicle 24. Furthermore, the three poles 11-21, 31-41 and 51-61 are open so that no
power from the removable shore power source 32 can get through to either the
16
electrical systems 26, or to the onboard power collector devices 36. In this
manner, by keeping poles 11-21, 31-41 and 51-61 open, the auto-change-over
switch 34 isolates the power collector devices 36 from the power from the
removable shore power source 32. This greatly reduces the risk of accidental
injury to maintenance workers working on the railway vehicle 24 in the
maintenance area.
Shown in Figure 7 is a more general flow diagram of the process performed by
the switch control module 38 in order to cause the auto-change-over switch 34 to
automatically switch from the first state to the second state. As shown in step 70,
~ the switch control module 38 detects when (1) the removable shore power
source 32 has been connected to the onboard electrical junction box 20; and (2)
when the load to the electrical systems 26 of the vehicle is less than a certain
threshold. At step 72, upon detection of these two conditions, the switch control
module 38 causes the auto-change-over switch 34 to change position such that
power is supplied to the vehicle's electrical systems 26 via the removable shore
power source 32, while simultaneously isolating the power received from the
removable shore power source 32 from the onboard power collector devices 36.
In accordance with the present invention, the control switch 42 can also be
manually operated in the case where the switch control module 38 fails to detect
the 24V control signal (for example, in the case where there is lack of control
power or faulty control circuitry). As such, in the case where the removable shore
power source 32 is in electrical connection with the onboard electrical junction
box 20, but has not been automatically detected by the switch control module 38,
then the control switch 42 can be manually operated in order to close the
removable shore power source position 42b-42b. Once the removable shore
power source position 42b-42b has been closed (and assuming that the load on
17
the electrical systems 26 has been detected to be below the certain threshold)
the auto-change-over switch 34 will be caused to change position.
Although in the schematic diagram of Figure 4, the switch control module 38 is
shown located remotely from the auto-change-over switch 34, it should be
understood that in practice, the switch control module 38 and the auto-changeover
switch 34 are one entity with internal connections. As such, the activation of
the auto-change-over switch 34 occurs automatically upon detection of the two
criteria described above with respect to steps 50 and 54 of Figure 5.
Switching from receiving power from the removable shore power source 32
back to the onboard power collector devices 36
Let us now consider the functioning of the onboard electrical junction box 20
when the removable shore power source 32 is removed from connection with the
onboard electrical junction box 20. Prior to disconnecting the removable shore
power source 32 from the onboard electrical junction box 20, the auto-changeover
switch 34 is in the second state, wherein the three poles 111-211, 311-411 and
511-611 are closed so that power can flow from the removable shore power source
32 to the electrical systems 26 of the railway vehicle 24. Furthermore, the three
poles 11-21, 31-41 and 51-61 are open so that no power from the removable shore
power source 32 can get through to the onboard power collector devices 36,
thereby isolating the onboard power collector devices 36 from the power from the
removable shore power source 32.
The process that occurs at the switch control module 38 in order to cause the
auto-change-over switch 34 to switch from the second state back to the first state
will now be described in more detail with respect to the flow chart of Figure 6.
18
Once the removable shore power source 32 has been removed from connection
to the onboard electrical junction box 20, the switch control module 38 will lose
the detection of the 24V control signal. As such, at step 60, the switch control
module 38 will detect that the presence of the removable shore power source 32
has been lost. In other words, the removable shore power source 32 is no longer
in electrical connection with the onboard electrical junction box 20. When the loss
of the 24V control signal is detected, the control switch 42 will open the
removable shore power source position 42b-42b and close the power collector
device position 42a-42a. This loss of the 24V control signal will occur faster than
the loss of the 750V power supply to the electrical systems 26, since pins Band
H are shorter than pins G and A. As such, the control switch 42 will open the
removable shore power source position 42b-42b before the power from the
removable shore power source 32 has dissipated.
At step 62, the switch control module 38 detects when the electrical load being
supplied to the electrical systems 26 has dissipated below a certain threshold. As
mentioned above, if the electrical load is not below the certain threshold, then the
auto-change-over switch 34 will be prevented from changing position for safety
reasons. This is represented by box 64 of Figure 6.
However, after the removable shore power source 32 has been removed for a
certain amount of time, the power within the onboard electrical junction box will
have dissipated and the load sensor module 40, which as described herein is a
current sensor module 41, will detect that the current being supplied to the
electrical systems 26 is below a certain threshold. When the current sensor
module 41 detects that the current being supplied to the electrical systems 26 is
below a certain threshold (such as less than 1A), then it moves from the normally
open position (NO) to the closed position (NC). When the current sensor module
41 is in the closed position, a signal is able to pass to the switch control module
19
38, such that the switch control module 38 is able to detect that the load on the
electrical systems 26 is below the certain threshold.
However, when the current sensor module 41 is in the open position, it means
that a load is being applied to the electrical systems 26, and no signal from the
current sensor module 41 is received at the switch control module 38. In the
absence of such a signal, the switch control module 38 is prevented from causing
the auto-change-over switch 34 from changing position. This is represented by
box 64 in Figure 6.
Although in Figure 6 step 60 is shown prior to step 62, it should be appreciated
that these two steps could have been shown in the reverse order, with step 62
shown prior to step 60. For example, if a shut off switch for the 750VDC circuit is
included within the circuitry of the removable shore power source 32, then it is
possible that a user could cut the power to the electrical systems 26 while the
removable shore power source 32 is still connected to the onboard electrical
junction box 20. In that manner, it is possible that the switch control module 38
would detect that the load to the vehicle's electrical systems 26 is less than the
certain threshold, prior to losing the 24V control signal that informs the switch
control module 38 that the removable shore power source 32 is still connected.
e Regardless of the order, once the switch control module 38 has detected that the
electrical load to the vehicle's electrical systems 26 is below a certain threshold
and that the removable shore power source 32 is no longer connected to the
onboard electrical junction box 20, at step 66 shown in Figure 6, the switch
control module 38 causes the auto-change-over switch 34 to change position
back to the first state, such that power is able to be supplied to the electrical
systems 26 of the railway vehicle 24 by a power rail 12 via the onboard power
collector device 36. When the auto-change-over switch 34 has switched back to
20
the first state, the three poles 11-21, 31-41 and 51-61 are closed so that power can
flow from the onboard power collector device 36 to the electrical systems 26 of
the railway vehicle 24. Furthermore, the three poles 111-211, 311-411 and 511-611 are
open so that no power from the removable shore power source 32 can get
through to the electrical systems 26.
No power operation
In the case where it is desired to work on the railway vehicle 24 with no power,
the control switch 42 shown in Figure 4 can be locked in the 0 position, such that
power is unable to be supplied to the vehicle's electrical systems 26 either by the
power rail 12 via the onboard power collector devices 36 or by the removable
shore power source 32.
More specifically, when the control switch 42 is locked in the 0 position, the poles
11-21, 31-41 and 51-61, and the poles 111-211, 311-411 and 511-611 of the auto-changeover
switch 34 are all in the open position such that no power is able to be
supplied to the vehicle's electrical systems 26.
Physical Characteristics of the Onboard Electrical Junction Box 20
Referring back to Figure 2, the onboard electrical junction box 20 is generally in
the shape of a rectangular box that can be mounted to the railway vehicle 24.
However, it should be understood that the onboard electrical junction box 20 can
be of any shape and configuration without departing from the present invention.
As described above, in accordance with the present invention, the electrical
switches contained within the onboard electrical junction box 20 are solid state
switches, which are lighter, less expensive and more reliable than traditional
21
electro-mechanical switches. Accordingly, the onboard electrical junction box 20
of the present invention is relatively light compared with existing junction boxes.
In a non-limiting embodiment, a high voltage (750V) electrical junction box in
accordance with the present invention may have a weight of between 40-55kg,
as compared with existing junction boxes that have a weight in the range of
120kg. In addition, a high voltage (750V) electrical junction box in accordance
with the present invention has been found to be approximately 40-50% less
expensive to manufacture than existing electrical junction boxes.
Although the present invention has been described in considerable detail with
reference to certain preferred embodiments thereof, variations and refinements
are possible without departing from the spirit of the invention. Therefore, the
scope of the invention should be limited only by the appended claims and their
equivalents.

•
I/We Claim:
1. An onboard electrical junction box for supplying power to an electrical
system of a vehicle, comprising:
an auto-change-over switch adapted to acquire:
i) a first state wherein power is supplied to the electrical
system from a power rail via at least one onboard power
collector device; and
ii) a second state wherein power is supplied to the electrical
system from a removable shore power source, wherein
during operation in the second state, the at least one
onboard power collector device is isolated from the power
supplied by the removable shore power source; and
a switch control module in electrical communication with the autochange-
over switch for causing the auto-change-over switch to
acquire the second state upon detection that:
(a) the removable shore power source has established an
electrical connection with the onboard electrical junction box;
and
(b) the electrical system of the vehicle is receiving power below
a predetermined threshold.
2. The onboard electrical junction box as defined in claim 1, wherein the
onboard electrical junction box further comprises a current sensor module
for detecting current supplied to the electrical system of the vehicle, the
current sensor module detecting that the electrical system of the vehicle is
not receiving power when the current being supplied to the electrical
system of the vehicle is below a certain threshold.
23
3. The onboard electrical junction box as defined in claim 2, wherein when
the current sensor module detects that the current supplied to the
electrical system of the vehicle is above the certain threshold, the autochange-
over switch is prevented from acquiring an alternative state.
4. The onboard electrical junction box as defined in claim 1t wherein the
onboard electrical junction box is a high voltage junction box.
5. The onboard electrical junction box as defined in claim 1, wherein the
switch control module comprises a spring return control switch, the spring
return control switch detecting that the removable shore power source has
established an electrical connection with the electrical junction box at least
in part on a basis of a low voltage control signal.
6. The onboard electrical junction box as defined in claim 5, wherein both the
spring return control switch and the auto-change-over switch comprise
solid state switches.
7. The onboard electrical junction box as defined in claim 5, further
comprising an indicator light for providing a visual indication to an operator
that the switch control module has detected that the removable shore
power source has established an electrical connection with the electrical
junction box.
8. The onboard electrical junction box as defined in claim 7, wherein upon
failure of the switch control module to detect that the removable shore
power source has established an electrical connection with the electrical
junction box, the spring return control switch being manually operable for
causing the auto-change-over switch to acquire the second state.
24
..
9. The onboard electrical junction box as defined in claim 1, wherein the
auto-change-over switch comprises a three pole motorized change-over
switch.
10. The onboard electrical junction box as defined in claim 1, wherein the at
least one onboard power collector device comprises at least one collector
shoe.
11. The onboard electrical junction box as defined in claim 1, wherein the
removable shore power source comprises at least one stinger cable
located within a vehicle maintenance area.
12. A method for supplying power to an electrical system of a railway vehicle
through an onboard electrical junction box, the onboard electrical junction
box being capable of supplying power to the electrical system of the
railway vehicle from a power rail via at least one onboard power collector
device, and from a removable shore power source, the method
comprising:
detecting when:
(1) an electrical connection between the removable shore power
source and the onboard electrical junction box has been
established; and
(2) the electrical system of the vehicle is not receiving power
from either the at least one onboard power collector device
or the removable shore power source;
upon detection of items (1) and (2):
i) causing power from the removable shore power source to be
supplied to the electrical system of the vehicle; and
25
ii) causing the power from the removable shore power source
to be isolated from the at least one onboard power collector
device.
13. The method as defined in claim 12, wherein upon detection of items (1)
and (2), the method comprises causing an auto-change-over switch that is
part of the onboard electrical junction box to switch from a first state,
wherein power is supplied to the electrical system from the power rail via
the at least one onboard power collector device, to a second state wherein
power is supplied to the electrical system from the removable shore power
source and the at least one onboard power collector device is isolated
from the power supplied by the removable shore power source.
14. The method as defined in claim 13, wherein the auto-change-over switch
comprises a three pole motorized change-over switch.
15. The method as defined in claim 12, wherein detecting that the electrical
system of the vehicle is not receiving power from either the at least one
onboard power collector device or the removable shore power source
comprises detecting when a current supplied to the electrical system of
the vehicle is below a predetermined threshold.
16. The method as defined in claim 13, further comprising preventing the
auto-change-over switch from acquiring an alternative state when a
current supplied to the electrical system of the vehicle is above a
predetermined threshold.
17. The method as defined in claim 12, wherein detecting that the removable
shore power source has established an electrical connection with the
26
.,
electrical junction box is performed at least in part on a basis of a low
voltage control signal from the removable shore power source.
18. The method as defined in claim 12, further comprising providing a visual
indication to an operator indicating that the removable shore power source
has established an electrical connection with the electrical junction box.
19. The method as defined in claim 12, wherein the onboard electrical junction
box is a high voltage junction box.
I> 20. A system for providing power to an electrical system of a railway vehicle,
the system comprising:
at least one onboard power collector device for collecting power
from a power rail; and
an onboard electrical junction box in electrical communication with
the at least one onboard power collector device, the onboard
electrical junction box comprising (i) an auto-change-over switch
adapted to acquire: (1) a first state wherein power is supplied to the
electrical system from the power rail via the at least one onboard
power collector device; and (2) a second state wherein power is
supplied to the electrical system from a removable shore power
source, wherein during operation in the second state, the at least
one onboard power collector device is isolated from the power
supplied by the removable shore power source; and (ii) a switch
control module in electrical communication with the auto-changeover
switch for causing the auto change-over switch to acquire the
second state upon detection that (a) the removable shore power
source has established an electrical connection with the onboard
27
electrical junction box; and (b) the electrical system of the vehicle is
receiving power below a predetermined threshold.