[0001] The invention relates to an actuating and monitoring module, particularly for operating
units, i.e. wayside equipment, of railway systems or the like, comprising:
a source of a DC power signal;
a line for supplying said power signal, also known as control signal, to said operating
unit, which line connects the outputs of the power signal source to the inputs of
the operating unit;
switching means in the power signal supply line for switching the operating unit on
and off by remote enabling/disabling controls.
[0002] Particularly, the invention addresses actuating and monitoring modules for railway
systems or the like, in which the control or actuating signal to the operating unit
is a Direct Current signal. Furthermore, this actuating and monitoring module shall
be operable in railway systems in which the train is supplied with Alternating Current
power.
[0003] Typical operating units are switch machines for railway switches or the like and/or
other wayside equipment having solenoids controlled by a central station.
[0004] Railway equipment or operating units are arranged in remote positions, at a long
distance from the actuating and monitoring module, which is generally situated in
the premises that also contain other control and monitoring units, known as cabins.
[0005] Therefore, there exists on the one hand the need of reducing the number of conductors
used to connect the actuators and the wayside devices, the system being only partly
distributed, as the central location is in series communication with the various zone
controllers (containing the equipment actuating subsystem), which may be even placed
at a considerable distance (2 - 3 km) from the wayside equipment. On the other hand,
the conductors of the communication lines shall still comply with length limits, imposed
by electric and electronic needs.
[0006] In the particular field of railway systems, actuating and monitoring modules and
operating units must operate at high degrees of safety and in a vital manner. Thus,
should any malfunctioning occur, the units affected thereby are brought back to safety
conditions, which are generally restrictive conditions.
[0007] Particularly, when AC power is supplied to trains, the safety conditions for operation
on AC electrified lines essentially require protection against any undue control caused
by induced and conducted voltage at 50 Hz, as well as a protection key on the feedback
signal, which in prior art system is a fixed 400 or 120 Hz carrier.
[0008] An undue control may be caused by the fact that, if one of the conductors of the
communication line is in contact with the ground at two locations, i.e. one at the
wayside device, i.e. the operating unit, and the other near the cabin, which contains
the actuating and monitoring module, an induced and/or conducted AC noise voltage
may occur on that conductor, due to the traction current at 50 Hz. In this case, if
an AC-to-DC converter is provided at the output of the module, the noise voltage generates
a current having a non-zero average value, circulating across the converter, the non
faulty conductor and the load. Thus, this noise signal may simulate an undue accidental
control signal.
[0009] An undue feedback may be caused by the presence of a signal having a certain frequency
in the cable, still in case of a double ground fault. Once more, the noise signal
may simulate an undue feedback signal, which might be interpreted as an indication
that the remote operating unit has switched to a given operating state, and false
information might be generated thereby.
[0010] As is better explained below in the disclosure, the solution to these problems of
prior art actuating and monitoring modules is not obvious at all. Particularly, the
need to improve safe control and/or monitoring using vital functions, in the context
of AC train electrification at 50 Hz, and the need to reduce or maintain the number
of conductors in communication lines are at least partly in contrast with each other.
[0011] Therefore, the invention has the object of providing an actuating and monitoring
module which, using simple and inexpensive arrangements, overcomes the safety problems
of prior art modules having the same basic operation principles, while improving other
safety features not directly associated to the AC traction problem.
[0012] First, the invention solves the above problem by an actuating and monitoring module,
particularly for operating units, i.e. wayside equipment of railway systems or the
lile, as described hereinbefore, which has automatic switching means for switching
the inputs of the unit and/or the outputs of the power signal source to the short
circuit state, in the disabled unit state, i.e. with no power signal on the supply
line.
[0013] Advantageously, the switching means include at least two relays, one of which is
connected in series with at least one conductor of the supply line, whereas the second
relay is connected in series with a short-circuit line for shorting the power signal
outputs of the power signal source and/or the power signal inputs of the operating
unit, a third protection relay being connected in series with at least one second
conductor of the power signal supply line, the latter relay disconnecting said conductor
and being open when the operating unit is in its idle condition, i.e. with no power
signal, and closed when the operating unit is in its operating condition, i.e. in
the presence of a power signal.
[0014] Particularly, the equipment or operating units referred to herein include the so-called
switch machines, which are driven by a DC motor. For the switch points to be driven
in either direction from either operating position, known as "normal" or "reverse"
position, the polarity of the power signal supplied to the motor has to be reversed.
This occurs thanks to a supply line having three conductors, two of which are for
the power signal and are alternately connected to the power output of a source of
said power signal and one is a return conductor for said power signal, which is common
to the two alternating operating states of the supply line.
[0015] More generally and without being bound to the case of switch machines, the invention
contemplates an operating unit having three inputs, i.e. one input for a common power
signal return conductor and two further inputs for alternating supply of the power
signal to one of said inputs using two separate power signal supply conductors, each
connected to one of said two further inputs and each alternately connectable to one
output of the power signal source, there being provided at least three relays:
a first and second actuation or control relays which have disconnecting contacts connected
in series to both supply conductors and the disconnecting contacts of said two actuation
or control relays being connected in series with each other in the same conductor
and operating in inverted arrangement, wherefore by energizing either actuation or
control relay one of the two inputs of the operating unit are alternately connected
to the output of the power signal source.
a third short-circuit relay in a line for short-circuiting connection of the inputs
of the operating unit to each other and/or to the outputs of the power signal source,
and which short-circuit relay has disconnecting contacts which are connected in series
in said short-circuit line and which disconnecting contacts are normally closed, with
said inputs and/or said outputs in a short-circuit state, when said two actuation
or control relays are in a state of disconnection of the corresponding conductor,
said short-circuit relays being excited to the short-circuit line contact opening
state by the signal that energizes at least one or both of said actuation or control
relays.
[0016] According to an advantageous embodiment, the third relay may operate through a pair
of normally closed contacts of each of the two actuation or control relays.
[0017] According to an advantageous embodiment, a fourth protection relay is provided which
has contacts connected in series to the return signal conductor in the power signal
supply line, which protection relay is in the open contact state when there is no
control signal coinciding with the signal that energizes at least one of said two
actuation or control relays and the short-circuit relay.
[0018] In the particular embodiment specifically designed for motor-driven switch machines,
which switch machines are used to throw the switch points of a turnout or a switch
between two opposite limit stop positions, i.e. normal and reverse, said switch machines
having three inputs, including one common input for a power signal return conductor
and two inputs for alternate supply of the power signal, each causing, when supplied
with said power signal, the motor to rotate in either direction, the module of the
invention thus comprises
two conductors for supplying the power signal to each of the two power signal inputs,
which conductors are designed to be alternately connected to the power signal output
of the power signal source by means of two actuation or control relays, each of which
actuation or control relays has contacts for disconnecting either conductor, operating
in inverted mode, the disconnecting contacts of the two actuation or control relays
being connected in series with each other in each of the two power signal supplying
conductors;
a short-circuit line that connects the outputs of the power signal source and/or the
inputs of the switch machine when there is no power signal or the actuation or control
relays are not energized, while the disconnecting contacts of the two power signal
supplying conductors are closed, and which short-circuit line includes a short-circuit
relay having disconnecting contacts that are normally closed when said relay is in
the disenergized condition, said relay being controlled by the signal that controls
the supply or control relays.
[0019] Here again, a protection relay is advantageously provided, whose disconnecting contacts
are located in the power signal return conductor and which is energized to the open
state by a signal coincident in time with the disenergization state of the two actuation
or control relays, which signal is generated by a source other than that of the signal
for controlling the two supply or control relays.
[0020] In a further improvement of the invention, the equipment, operating units or more
specifically the switch machines also have means for generating a signal to check
that the equipment, operating units and/or particularly the switch machines have switched
to the proper operating states. These means include an oscillatory circuit that generates
a signal at a predetermined frequency when the unit switches to one of said predetermined
operating conditions, the oscillatory circuit being driven to generate the feedback
signal at the predetermined frequency when a capacitor of predetermined capacitance
is introduced in a loop of said circuit, by means of switches that are switched closed
by means for detecting one of said operating states, whereas feedback signal receiving/transmitting
means are provided, preferably connected in series with the short-circuit line.
[0021] In a preferred embodiment a line may be provided for communication with the operating
unit to be controlled, such as a supply line for transmitting power signals of the
operating unit, i.e. control signals as described above, which line has at least two,
three or more conductors,
which feedback signals are generated by an oscillatory circuit which generates a signal
at a predetermined frequency when the operating unit switches to either of the predetermined
operating states;
the oscillatory circuit being formed by an inductor contained in the actuator, the
conductors of the communication lines between the control actuator and the operating
unit and a separate capacitor for each predetermined operating state of the operating
unit, the operating unit having feedback switch means operated thereby upon transition
from a first to a second of said predetermined operating states;
the whole in such a manner that, as an operating state is attained, a feedback signal
having the predetermined unique frequency is automatically generated, which feedback
signal is detected by detection means of the actuating and monitoring module,
which detection means include means for analyzing the feedback signal to check the
correctness of the feedback signal frequency and generate a signal to indicate that
the operating unit has correctly switched to the corresponding operating state,
and which module of the invention further includes means for modulating the feedback
signal according to a predetermined modulation protocol.
[0022] Various embodiments may be envisaged, including one that includes a local feedback
signal generator having a local feedback signal carrier generating section and a local
pulse amplitude modulation signal section, which local feedback signal generator is
triggered to generate said feedback signal by a variable capacitance resonant circuit
loop, which is composed of a local inductor, a resistor provided by the conductors
of the communication line between the module and a remote operating unit and the contacts
of the feedback switch of said remote operating unit, and a separate capacitor for
each operating state of the remote operating unit, which capacitors are located in
the remote operating unit and are alternately connected together in the resonant grid
by the feedback switch depending on the operating state of the operating unit, whereas
the module includes a local receiver having means for analyzing the feedback signal
with respect to the frequency of the feedback signal carrier and the frequency of
the pulse amplitude modulation of said feedback signal carrier, and which feedback
signal analyzing means are of the vital type and generate a vital signal indicating
that the operating unit has correctly switched to the corresponding operating state.
[0023] Thanks to the above arrangements, the actuating module of this invention obviates
the above mentioned prior art drawbacks.
[0024] Further improvements will form the subject of the dependent claims.
[0025] The features of the invention and the advantages deriving therefrom will appear more
clearly from the following description of a few non-limiting embodiments which are
illustrated in the accompanying drawings, in which:
Figure 1 is a simplified diagram of a Vital Computer Station Apparatus for large stations
including the actuating module of the present invention which is used as a turnout
control module.
Figure 2 is a block diagram of a module of this invention used as a turnout control
module according to the example of Fig. 1.
Figure 3 shows a simplified diagram of the communication interfaces of the module
of Fig. 2.
Figure 4 is a block diagram of the Actuating Board of the module of the previous figure.
Figure 5 shows a detailed diagram of the module configuration regarding control, short-circuit
and protection relays and generation of the control signals, in an embodiment in which
three conductors are only provided for supplying both the power signal and the feedback
signal.
Fig. 6 shows a variant embodiment in which the turnout is connected by six conductors,
including three conductors for the power signal and three conductors for the turnout
position feedback signals.
Fig. 7 shows the connections of a Monitoring and Diagnostics Board.
Figure 8 is a block diagram of the switch point Position Monitoring Section.
Figure 9 is a block diagram of the diagnostics module.
[0026] Figure 1 is a diagram of a system known as Vital Computer Station Apparatus for large
stations which uses a turnout control module, referred to herein as MGD, designated
by numeral 1, representing an embodiment of the most general actuating module of this
invention.
[0027] As shown in Figure 1, the system defined as Vital Computer Station Apparatus comprises
a Central Logic Computer 2 with one or more vital operator interfaces, designated
by numeral 3, connected thereto. The Central Logic Computer 2 executes a logic program
for monitoring the railway system and transmits controls to Zone Logic Computers (ZLC),
designated by numeral 5, through a communication network 4. These Zone Logic Computers
are designed to generate actuating or state-changing controls for wayside equipment,
such as light signals, turnouts, etc. In Figure 1, numeral 6 generally designates
the wayside equipment, numeral 5 designates the Zone Logic Computer which is designed
to control the switch machines of the turnouts, and numeral 5' designates other Zone
Logic Computers.
[0028] The Zone Logic Computers transmit controls to actuating or driver modules, which
generate the power signals for controlling or actuating the wayside equipment and
receive feedback signals therefrom, and which include the module of this invention.
[0029] Figure 2 is a block diagram of the actuator architecture and Figure 3 shows the interfaces
to the other system units.
[0030] The turnout control actuating module of this invention interfaces (arrow 101) with
the Vital Computer Station Apparatus to receive the turnout throwing controls and
further has interfaces with the mains, arrow 201, with the operator, arrow 301, and
obviously with the turnout, arrow 401 and with a diagnostics system, arrow 501.
[0031] The interface 201 with the power supply system provides a three-phase supply current,
380 VAC, 50 Hz.
[0032] The interface 101 connects the actuator 1 to the Zone Logic Computer 5 and allows
reception of controls and transmission of wayside unit feedbacks through the vital
I/O; particularly three feedback signals, KN, KR and DISALM are transmitted to the
Zone Logic Control 5, and the Zone Logic Computer transmits the two N and R control
signals to the actuator 1 for throwing the turnout switch points to either operating
positions, known in the art as Normal position "N" and Reverse position "R".
[0033] The actuator interfaces with the diagnostics system, by the interface 501, through
a communication network (designated by numeral 8 in Fig. 1) and known as Field Diagnostic
Bus or FDB. All the diagnostics data of the external unit 6 are transmitted through
such interface.
[0034] The interface 401 with the unit 6, i.e. the switch machine of the turnout uses special
terminal boxes, which are mounted to the unit and contain devices that form the electric
termination of the position monitoring circuit.
[0035] Two connection arrangements may be provided between the actuator 1 and the unit 6,
which will be further described hereunder in greater detail.
[0036] In a first arrangement, the actuator 1 is connected to the unit 6 through a cable
having 3 conductors C1, C2, C3 (classical connection: control + feedback). In this
case, both the power signals for actuation of the switch machine motor and the switch
point position feedbacks (Figs. 2 and 5) are transmitted through said three conductors
C1, C2, C3.
[0037] In an alternative embodiment, two separate cables are provided, each having 3 conductors
C1, C2, C3 and C1', C2', C3', i.e. a first cable having three conductors C1, C2, C3
for control signals and a second cable, also having three conductors C1', C2' and
C3' for feedback signals. The latter connection arrangement allows to increase the
maximum distance between the cabin and the unit. This is also required if the DC motor
inside the switch machine has no mechanical limit contact (which means that the control
current is not automatically switched off at the end of the control).
[0038] The user interface 301 includes:
Signal lights to show the operating state of the subsystem;
Test Points to be used for measuring certain electric magnitudes of the actuating
module;
Devices for configuring the functions of the actuating module.
[0039] In operation, the module of this invention is designed to accomplish the functions
of: controlling the turnout; monitoring switch point positions.
[0040] Furthermore, the actuating module 1 of the present invention acts as an interlocking
subsystem and is required to meet certain safety conditions, i.e. any unsafe state
must be detected and the system must be later forced into a safe state in as little
time as to ensure compliance with any application-specific requirements.
[0041] Safety states for the actuator of the invention include: no power supply to the unit;
no unit position monitoring.
[0042] Particularly, the module 1 is based on an inherent fail-safe architecture: the actuator
1 transfers power to the unit 6 in a vital manner, i.e. only when there is a control
intention in the logic 5, which is expressed through the actuation of a Vital Output
port 101 and with a sufficient delay to cover the response time of the Zone Logic
Computer 5 in case of undue control.
[0043] Concerning the position monitoring functions, the MGD subsystem uses operation principles
that were already used in prior art actuators operating in AC electrified lines.
[0044] The actuating module 1 is an assembly composed of a disconnecting part and a module,
which is in turn composed of hardware boards having well-defined functions, as reflected
in principle by Fig. 2.
[0045] The boards are function-specific, namely:
a power supply panel, containing the electric disconnecting device 10 of the module,
an Actuating Board 11, which generates the voltage required for controlling the unit
and incorporates the required control circuits,
a Monitoring and Diagnostics Board 12, which essentially handles the turnout position
monitoring functions, the steps of controlling and protecting it, as well as all unit
diagnostics and communication with the diagnostic system.
the Actuating Board 12 comprises electronic circuits and relays, which accomplish
the following functions:
an AC/DC conversion unit 112 for adequate power supply to the unit;
relays R1 and R2 for controlling the N or R throwing function, having inverted R and
N_ contacts, designated by R11 and R12, which are located in a conductor C4 designed
to short the inputs of the unit 6 and/or the AC/DC conversion unit 112;
auxiliary functions required for proper operation of the electronic circuits;
low power circuit supply;
protection relay R3 in the conductor C3.
[0046] It shall be noted that, in Figure 1 and in the others, the relays are indicated by
the electromagnetic energizing unit as a part of the whole and the contacts are actually
shown in their position in the conductors C1, C2, C3 and C4.
[0047] Thus, as shown in Figure 2 and in Figures 5 and 6, the motor of the switch machine
is of the DC type and, for rotational drive in either direction to cause switch point
displacement from normal position to reverse position and vice versa, the two conductors
C1 and C2 that supply the power signal to one input for rotation in one direction
and to another input for rotation in the opposite direction, respectively incorporate
normally open contacts of the relay R1 which are closed in the energized state of
the relay R1 and normally closed contacts of the relay R2 which are open when the
relay R2 is in the energized state and have a reverse operation as compared with the
normally open contacts of the relay R2 incorporated in the conductor C2, and connected
in series with the normally closed contacts of the relay R1, which are open when the
relay R1 is energized. This configuration allows the power signal to be transmitted
either on the conductor C1 or on the conductor C2 depending on whether the relay R1
is energized for throwing the switch points to the normal position or the relay R2
is energized for throwing the switch points to the reverse position.
[0048] Referring to Figure 4, the Actuating Board is composed of the following functional
units:
an EMI filter 212 for reducing noise introduced in the 380 V network;
an inrush current limiter 312, for attenuating initial start-up current peaks;
an uncontrolled AC/DC converter 112';
an unstabilized and isolated DC/DC converter 112" which forms the conversion unit
112 with the AC/DC converter;
an auxiliary power supplies 512, also used by the Monitoring Board;
a PWM signal generator 412;
control relays R1, R2 which set the direction of rotation of the motor of the switch
machine in the energized state, as described above and as better explained hereafter
and disconnect the output of the power source 112 and short circuit C4 the wires C1,
C2, C3 in the disenergized state.
[0049] All the above functional units cooperate to perform the turnout control actuation
function.
[0050] The control disconnection function (SEZ) is accomplished by a galvanic power disconnection
device 10; this disconnection device 10 ensures protection for the wayside assistant
of the DM in case of power failure and/or in case of turnout maintenance.
[0051] The throw control (to the normal "N" or reverse "R" positions) is implemented by
three printed circuit relays R1, R2, R3 whose normally open contacts NR1, RR2 or normally
closed contacts N_ and R designated by R11 and R12 are introduced in the power circuit
as shown in Figures 5 and 6. Particularly, two normally closed contacts N_ and R_,
designated by R11 and R12, of the relays R1 and R2 hold the power source 112 shorted
C4, when there is no control signal KN or KR and, as better explained hereafter, allow
circulation of the alternating current of the monitoring circuit overlying the control
circuit.
[0052] The third relay R3 is an auxiliary protection relay which is energized in the control
step by circuits other than those that control the relays R1 and R2. The protection
relay R3, which is normally disenergized, is used to disconnect the wayside cable
(by operating on the common return conductor C3) from the AC-DC converter 112 on the
power output and thereby afford considerably improved safety conditions in the idle
state, particularly on AC electrified lines, in case of cable insulation failure to
the ground.
[0053] More in detail, the Actuating Board 12 is composed of an AC/DC power converter, whose
output is vitally enabled by vital outputs of the zone logic computer 5; this "enabling"
signal is indicated in Fig. 4 and Fig. 7 as ON_Vit.
[0054] Furthermore, Fig. 2 and Fig. 4 shows that, from the moment in which the Zone Logic
Computer (ZLC) exerts its control intention by transmitting the control signal Kn
or Kr, energization of the unit 6 may only occur after a minimum time τ. This "delay"
is vitally ensured by a suitable delay circuit 612.
[0055] Finally, an input is provided for a stop signal which has a protective function,
for example, in case of abnormal power absorption by the unit and any other hazardous
event, thereby preserving the integrity of the electronics of the Actuating Board
112 and/or the motor in the switch machine 6.
[0056] Figure 7 shows the connections of the Monitoring and Diagnostics Board. As shown
in Figure 7, the board interfaces with:
[0057] The local Logic Computer 5 (ZLC) through the three signals: KN, KR and DISALIM, transmitted
to three vital inputs respectively and through the N and R signals received from two
vital outputs;
the unit 6, i.e. the switch machine, to detect its operating state, i.e. the position
of its switch points (Field _Ctrl _ N and Field _Ctrl _R signals);
the Actuating Board 12, from which it receives the I MAN signal (containing the information
about the level of current circulating through the power output) and the service power
supply, and to which it transmits the N and R control signals for the relays R1 and
R2, the stop signal, which turns the power converter 112 off at the end of the control
operation or in abnormal situations, and the vital enabling signal ON_vit, which enables
the DC/DC converter 112".
[0058] The board is composed of three functional sections:
a turnout Position Monitoring Section (having vital operation)
a Protection and Supervision Section
a Diagnostics Section.
a turnout Position Monitoring Section
[0059] This section implements the TC and RC functions, i.e. transmission and reception
of feedback signals for determining the position of the switch points. It accomplishes
the turnout state monitoring functions, and communicates information through two position
feedback signals KN and KR, connected to two vital inputs of the Zone Logic Computer
(ZLC) 5.
[0060] The feedback signal is transmitted and received at about 400 Hz from and to the unit
through transformers T1 and T2, the former T1 for the Normal switch point position
signal KN and the latter T2 for the Reverse switch point position signal KR.
[0061] As mentioned above, the interface with the unit 6 may include 6 or 3 conductors,
depending on whether or not a dedicated wire is used for feedback signals.
[0062] Figures 5 and 6 show two simplified diagrams of connection options.
[0063] It will be appreciated that, in the classical 3-wire connection as shown in Figure
5, the transformers T1 and T2 for transmitting and receiving signals at 400 Hz are
in the short-circuit branch C4 of the power output whereas, in the option with a separate
cable for feedback signals C1', C2', C3', as shown in Figure 6, the transformers T1
and T2 only have one point in common with the power circuit. Complete separation is
not possible, due to the need for the Cable Insulation Check Section of the Monitoring
Board, which is directly connected with the output of the Power Section, to check
the efficiency of such insulation on both wires.
[0064] In the first option, i.e. the classical option of Figure 5, the presence of the auxiliary
control relays R1 and R2 allows the position monitoring transformers T1 and T2 to
be connected in parallel with the power circuit, thereby avoiding the need for oversize
series-connected transformers designed to have the DC current requested by the motor
flowing therethrough.
[0065] Figure 8 shows the block diagram of the switch point Position Monitoring Section.
[0066] The operating principle of safe detection of switch point position, when switch points
have been thrown into the proper position, relies on the circulation of current at
a frequency of about 400 Hz generated by an oscillator (carrier generator); this oscillator
is only triggered if the cpn or cpr contact of the position cam inside the switch
machine inserts a capacitor Cn or Cr in the circuit loop, which capacitor is in the
terminal box 106 of the wayside device 6.
[0067] As mentioned above, the two carrier generators 20 and 21 are amplitude modulated
to provide an additional safety key, particularly needed in 50 Hz drive system applications.
An ON/OFF amplitude modulation is selected, having a 100% modulation depth, a 100
ms period and a duty cycle D = 90%.
[0068] Referring to Fig. 8, it can be appreciated that the feedback signal is transmitted
and received through transformers, whose high isolation secondary windings are connected
to the unit.
[0069] If the amplitude of the feedback signal exceeds a certain level and the carrier frequency
and the modulating frequency are recognized, then the corresponding vital input to
the Zone Logic Computer (ZLC) 5 with the KN or KR signals is enabled. In the idle
state, in case of a sufficiently long monitoring failure, the RIT timer block 613
maintains the corresponding vital input of the local Logic Computer (ZLC) 5 "low"
for as long as required for the latter to detect it; thus, it allows the local computer
5 to detect any so-called "short monitoring failures".
[0070] The module of the invention also has a Protection and Supervision Section. This section
has operational supervision functions. These functions are accomplished by a microcontroller,
and the section receives information by interfacing with the other functional blocks
of the actuating module 1. The Protection Section energizes the control relay R1 or
R2 according to the control intention (N and R signals) of the local Logic Computer
(ZLC) 5; after the control step, the protection section also energizes the monitoring
relays CTN or CTR, which further allow the feedback signal generated by one of the
two transmitters T1 and T2 as described above to flow into a single receiver, which
is always on.
[0071] The Supervision and Protection Section is also designed to disable power delivery
by the Actuating Board 12 during the control step, through the control protection
function, by generating stop and DISALIM signals or a DISALIM signal only, in response
to predetermined events.
[0072] The events that trigger the control protection function are:
Surge at the power output;
A voltage at the power output lower than a predetermined threshold (undervoltage);
A number of successive control operations per minute greater than admitted;
Overtemperature of power transistors;
Control operation timeout;
Unacknowledged control.
[0073] The stop signal has the purpose of inhibiting the DC/DC converter 112" of the Actuating
Board 12. In the above cases in which a stop signal is triggered, the DISALIM signal
is also generated to drive the third vital input of the local logic computer 5.
[0074] The control protection function may be also performed outside the control step, in
case of wayside cable failure, in the loop (not monitored) of the next control operation;
in this case, the DISALIM signal is only generated.
[0075] For improved reliability of the surge protection function, a periodic test is performed
to check proper operation of the circuits designed to receive the control current.
[0076] As shown in Figure 9, the Diagnostics Section receives the following parameters from
the two Position Monitoring and Protection and Supervision Sections:
Control current (DMD, DP);
N and R control voltage (DMD);
frequency of feedback signals (DT, DR);
wayside cable insulation (CIC);
turnout position feedback signals KN and KR (DT, DR);
and makes them available for the diagnostics system through an interface with the
ECHELON NODE 22 (FDB network), as well as other information about the status of the
actuating module (i.e. correct operation or failure)
[0077] The Diagnostics Section is mainly implemented in the microcontroller 24 that performs
the Protection and Supervision functions, as shown in Figure 9.
[0078] Such microcontroller 24 directly acquires all the magnitudes to be subjected to diagnostics,
interfaces with the Cable Insulation Check circuit 25 (CIC) and with the Echelon "node"
22, which is used as a communication unit on the Field Diagnostic Bus 8 (FDB) network.
[0079] Furthermore, the microcontroller 24 performs tests on the cable insulation check
circuit, either upon user's request (user interface panel) or in a periodic and automatic
manner.
[0080] The Cable Insulation Check (CIC) section 25 essentially comprises a 0.5 Kz square
wave generator, connected to the input of the wayside cable C1, C2, C3 through a resistor
of a suitable resistance, and a circuit for vector measurement of the absorbed current,
which can detect cable insulation failure to ground, i.e. any reduction of cable insulation
resistance, which can be configured in a step-wise manner.
[0081] The operation of the actuating module as described above and with particular reference
to its turnout control embodiment is as follows:
[0082] The switch machines 6 are controlled by the actuator 1 which provides power supply
to the unit 6 and performs monitoring functions thereon.
[0083] During the control operation, due to the special architecture of the system, the
feedbacks of the unit 6 are necessarily lost.
[0084] The interface is composed of two identical sections, one of which transmits at a
certain time the indication of the (normal or reverse) position of the turnout unit
6 to the local Logic Computer (ZLC) 5. During the control operation, none of the two
sections provides a valid output for the ZLC, as the mechanical members of the switch
machine disconnect the contacts of both positions and the short circuit branch C4
of the power output is always open and prevents generation of feedback signals Kn
and Kr.
[0085] The operation of the actuator implies the following steps:
Step I
[0086] Assuming a turnout in "normal" position, the output transformer T1 of the normal
position monitoring transmitter is closed on the remote capacitor CN. This triggers
400 Hz oscillation and enables relative position feedback (KN). The output transformer
T2 of the reverse position monitoring transmitter is closed on a low impedance, in
the classical case. Thus, its oscillator is off and the output KR is disabled. In
the 6-wire connection configuration, the above transmitter operates idly, thereby
causing an oscillation at a frequency from 700 Hz to 2.5 kHz, which cannot enable
the output KR.
Step II
[0087] Upon switching from normal to reverse, the Zone Logic Computer (ZLC) 5 enables its
vital output (R); after a short time, the CTN relay will be disenergized and the normal
KN feedback will be immediately lost, whereupon the control relay R1 is energized.
Then, a control protection Stop signal is transmitted to enable operation of the DC/DC
converter 112". After another short vital delay, the ON_Vit power supply is enabled,
to energize first the protection relay R3 and then the section for controlling the
power DC/DC converter 112". Now, the actuator provides a rated voltage of 150 VDC
to the winding of the motor, which causes displacement in the "reverse" direction.
Step III
[0088] When the motor of the switch machine terminates rotation (the control time depends
on the type of switch machine used), causes the control circuit in the switch machine
to open, whereby DC power failure occurs. This event initiates the end sequence of
the control step; the control protection Stop signal is generated again whereupon
the 150 VDC is cut off. Then, the control relay R2 is released and restores the short-circuit
of the power output. Immediately after, the monitoring relay CTR is energized; this
allows disenergization of the protection relay R3 which cuts off the vital power supply
ON_Vit. If the switch points have moved to the required position, monitoring contacts
are established and insert the remote capacitor CR which triggers the reverse position
oscillator. Now, the resonance capacitor CR is connected instead of the motor winding,
allowing circulation of the 400 Hz feedback signal and, after an intrinsic delay time
(τc) a "1" output is obtained on the reverse position vital input (KR).
Step IV
[0089] Then, the system logic cuts off the control operation thereby disabling the corresponding
vital output (R).
[0090] According to one improvement, it is possible to also control and monitor switch machines
that do not automatically cut off current upon termination of the control operation.
In this case, a 6-wire connection is used, and the system may be configured to enable
the monitoring relay CTR after a configurable delay from the time of closure of the
control relay R2, regardless of whether the control current is cut off or not. In
this case, the end of the control operation is determined as the monitoring frequency
is reached and the corresponding feedback is obtained.
[0091] Thanks to the above construction, the actuating module of the invention can handle
abnormal operation statuses and ensure the highest safety.
[0092] Besides start up, there are substantially two distinct operating states: the former
is the state in which the module operates for most of the time and is characterized
by the lack of controls, with the monitored unit in the Normal or Reverse position;
the latter operating state is the one in which the unit is controlled, and feedbacks
are necessarily lost.
[0093] In addition to these two states, which represent normal operation of the module,
there are "abnormal" states, characterized by malfunctioning in the module, the unit
and connection therebetween.
[0094] The causes that lead to abnormal states and the behavior of the MGD will be described
below:
Current protection
[0095] This occurs during a control operation, with the unit being disenergized by a Stop
signal. At the same time, the DISALIM signal is also generated. The turnout may be
monitored or not.
Unacknowledged control
[0096] This event may occur in response to a control operation. An unacknowledged control
triggers a DISALIM signal. The turnout may be monitored or not.
Control operation Timeout
[0097] This event may occur during a control operation. Once the control operation timeout
is reached, the unit is disenergized, the control operation is interrupted and a DISALIM
signal is generated. The turnout may be monitored or not.
Undervoltage protection
[0098] This event may occur during a control operation. This protection does not disenergize
the unit, whereby the module will try and terminate the control operation. When the
latter is terminated, a DISALIM signal will be generated. The turnout may be monitored
or not.
Wayside cable failure protection
[0099] This event may occur when there is no control operation and the turnout is monitored,
in a normal or reverse position. In case of failure of the live pole of the monitoring
circuit for the position that is not monitored ("third wire") the module triggers
a DISALIM signal, to prevent voltage from being transmitted, during the next control
operation, to a circuit that has no load.
[0100] In case of a three-wire connection, this protection may be excluded during configuration.
[0101] In case of a six-wire connection, the above described detection is not significant.
Thus, protection has to be necessarily excluded during configuration.
[0102] Maximum allowed successive control operations in one minute
[0103] This event occurs at the end of the last admitted control operation. Once this control
operation is terminated, a DISALIM signal will be generated. The turnout may be monitored
or not. This protection may be configured during setup.
Overtemperature protection
[0104] This event occurs during a control operation. This protection does not disenergize
the unit, whereby the module will try and terminate the control operation. When the
latter is terminated, a DISALIM signal will be generated. The turnout may be monitored
or not.
Inefficient current sensing circuit protection
[0105] Periodic tests are performed for checking proper operation of control current measuring
circuits. Whenever a test fails, a DISALIM signal is generated.
1. An actuating and monitoring module, particularly for operating units, i.e. wayside
equipment, of railway systems or the like, particularly for switch machines, comprising:
a source of a DC power signal;
a line for supplying said power signal, also known as control signal, to said operating
unit, which line connects the outputs of the power signal source to the inputs of
the operating unit;
switching means in the power signal supply line for switching the operating unit on
and off by remote enabling/disabling controls.
characterized in that
it has automatic switching means for switching the inputs of the unit and/or the outputs
of the power signal source to the short circuit state, in the disabled unit state,
i.e. with no power signal on the supply line.
2. An actuating module as claimed in claim 1, characterized in that said means are electromechanical means.
3. A module as claimed in claim 1 or 2,
characterized in that said switching means include:
at least two relays, one of which is connected in series with at least one conductor
of the supply line, whereas the second relay is connected in series with a short-circuit
line for shorting the power signal outputs of the power signal source and/or the power
signal inputs of the operating unit,
whereas a third protection relay is connected in series with at least one second conductor
of the power signal supply line, the latter relay disconnecting said conductor and
being open when the operating unit is in its idle condition, i.e. with no power signal,
and closed when the operating unit is in its operating condition, i.e. in the presence
of a power signal.
4. A module as claimed in one or more of the preceding claims,
characterized in that the operating unit has three inputs, i.e. one input for a common power signal return
conductor and two further inputs for alternating supply of the power signal to one
of said inputs using two separate power signal supply conductors, each connected to
one of said two further inputs and each alternately connectable to one output of the
power signal source, there being provided at least three relays:
a first and second actuation or control relays which have disconnecting contacts connected
in series to both supply conductors and the disconnecting contacts of said two actuation
or control relays being connected in series with each other in the same conductor
and operating in inverted arrangement, wherefore by energizing either actuation or
control relay one of the two inputs of the operating unit are alternately connected
to the output of the power signal source.
a third short-circuit relay in a line for short-circuiting connection of the inputs
of the operating unit to each other and/or to the outputs of the power signal source,
and which short-circuit relay has disconnecting contacts which are connected in series
in said short-circuit line and which disconnecting contacts are normally closed, with
said inputs and/or said outputs in a short-circuit state, when said two actuation
or control relays are in a state of disconnection of the corresponding conductor,
said short-circuit relays being excited to the short-circuit line contact opening
state by the signal that energizes at least one or both of said actuation or control
relays.
5. A module as claimed in one or more of the preceding claims, characterized in that, as an alternative to the third short-circuit relay, the first and second actuation
or control relays have a pair of short-circuit contacts, which are controlled by said
actuation or control relays and are closed in the idle state of said actuation or
control relays.
6. According to an advantageous embodiment, a fourth protection relay is provided which
has contacts connected in series to the return signal conductor in the power signal
supply line, which protection relay is in the open contact state when there is no
control signal coinciding with the signal that energizes at least one of said two
actuation or control relays and the short-circuit relay.
7. A module as claimed in one or more of the preceding claims, characterized in that the relays are controlled by a microprocessor which receives feedback signals from
a Monitoring and Diagnostics board, which in turn generates said signals in response
to controls of a control logic unit.
8. A module as claimed in one or more of the preceding claims, characterized in that it comprises a delay circuit for introducing a time delay between the control signal
for actuating or enabling the operating unit and the transmission of the power signal
to the operating unit or the connection of the operating unit to the power signal
generator with said power signal at its output.
9. A module as claimed in one or more of the preceding claims, characterized in that the operating unit is equipped with means for generating feedback signals confirming
actuation and/or switching thereof to an operating state, which signals are generated
as the control operation or the operating function is performed by the operating unit
during power signal supply, said feedback signal generators being formed at least
partly of the short-circuit line or components connected to said short-circuit line.
10. An actuating module as claimed in one or more of the preceding claims,
characterized in that it is designed for actuation of a motor-driven switch machine, and which switch machine
throws the switch points of a turnout between two opposite limit stop positions, i.e.
normal and reverse, said switch machine having three inputs, including one common
input for a power signal return conductor and two inputs for alternate supply of the
power signal, each causing, when supplied with said power signal, the motor to rotate
in either direction, there being provided:
two conductors for supplying the power signal to each of the two power signal inputs,
which conductors are designed to be alternately connected to the power signal output
of the power signal source by means of two actuation or control relays, each of which
actuation or control relays has contacts for disconnecting either conductor, operating
in inverted mode, the disconnecting contacts of the two actuation or control relays
being connected in series with each other in each of the two power signal supplying
conductors;
a short-circuit line that connects the outputs of the power signal source and/or the
inputs of the switch machine when there is no power signal or the actuation or control
relays are not energized, while the disconnecting contacts of the two power signal
supplying conductors are closed, and which short-circuit line includes a short-circuit
relay having disconnecting contacts that are normally closed when said relay is in
the disenergized condition, said relay being controlled by the signal that controls
the supply or control relays.
11. An actuating module as claimed in claim 10, characterized in that it has a protection relay, whose disconnecting contacts are located in the power
signal return conductor and which is energized to the open state by a signal coincident
in time with the disenergization state of the two actuation or control relays, which
signal is generated by a source other than that of the signal for controlling the
two supply or control relays
12. An actuating module as claimed in claim 10 or 11, characterized in that the switch machine has means for generating a feedback signal, including an oscillatory
circuit that generates a signal at a predetermined frequency when the switch machine
switches to one of said two predetermined operating conditions, the oscillatory circuit
being driven to generate the feedback signal at the predetermined frequency when a
capacitor of predetermined capacitance is introduced in a loop of said circuit, by
means of switches that are switched closed by means for detecting one of said operating
states, whereas oscillating feedback signal receiving/transmitting means are provided,
preferably connected in series with the short-circuit line.
13. An actuating module as claimed in one or more of the preceding claims, characterized in that it has a pulse width modulation, which requires a modulating signal that can be generated
either by the microcontroller that controls the auxiliary relays and diagnostics,
or by an active wayside circuit, connected in parallel to the remote capacitors, or
to said capacitors as mentioned in the preceding claim, and supplied by said feedback
signal on which the modulator operates.
14. An actuating module as claimed in one or more of the preceding claims, characterized in that it comprises means for detecting the oscillating feedback signal, which means comprise
feedback signal analyzing means for checking the correctness of the carrier frequency
and the modulating frequency of the feedback signal and generate a signal to indicate
that the operating unit has correctly switched to the corresponding operating state.
15. A module as claimed in one or more of the preceding claims, characterized in that it comprises means for detecting the lack of any feedback signal, which means compare
the time during which no feedback signal has been detected with an adjustable maximum
allowed threshold, and which means control, with the actuator in the idle state, means
for locking, suppressing and/or delaying the signal indicating that the operating
unit has correctly switched to the corresponding operating state during a predetermined
time longer than the maximum cycle time of the logic of the zone computer, or generate
a signal indicating that the operating unit has not correctly switched to the operating
state when the time during which no feedback signal has been detected exceeds said
maximum allowed threshold.
16. A module as claimed in one or more of the preceding claims, characterized in that it includes contacts that are normally closed in the disenergized state of the actuation
or control relays.
17. A module in which the unit control or monitoring functions are obtained with the help
of force guided relays, which can be exposed to sticking and undue energizing in case
of failure, wherefore such relays must be all monitored by each other and/or by the
electronics, to avoid undue unit controls (not required by the apparatus) and to initiate
a position monitoring failure if said relays are not switched to the position desired
by the apparatus logic.