MX2014015853A - Equipment and method for generating regulated electric arcs in direct current. - Google Patents

Abstract

The present invention comprises equipment and methods for generating electric arcs with regulated direct current by means of: a three-phase power converter, which transforms the alternate current into direct current in a controlled manner according to the test parameters; a control unit for regulating said direct current under test; where the current sensor performs the measurement of the direct current in the electric arc and feeds back its value to the control unit; the optic sensor of electric arc presence allows the start and end of said electric arc to be detected, following the detection of the start the time of application of said electric current is measured by means of the control module; where the electrode arrangement allows the circuit of said electric current to be closed through a fuse element for setting the electric arc, which is controlled by the control unit.

Description

EQUIPMENT AND METHOD FOR GENERATING REGULATED ELECTRIC ARCHES IN DIRECT CURRENT Field of the invention The present invention belongs to the technical field of the generation of electric arcs; more particularly, it belongs to the generation of electric arcs regulated in direct current with electro-optical detection of arc start and arc termination based on time and electric charge.

BACKGROUND OF THE INVENTION The applications for controlled electric arcs are diverse in the electrical industry and mechanical metal, however the control of electric arcs lies in the behavior of the arc or plasma that is produced in the air from a flow of ions or electric charges in air or controlled gases, since their electrical behavior in principle is a non-linear electrical resistance with a reverse behavior to a conventional standard resistance where the potential increases as a function of the current increase. In the case of an electric arc the potential decreases with the increase in current. The previous presents technical problems of regulation and control of the current, in addition to the erratic problems of the behavior of the arcs.

A case of application of controlled arcs in direct current CD is the test of arc in wires of guard wire known as OPGW (for its acronym in English) where the requirement is in accordance with international standards, requires the transfer of electrical charge from a finished electrode to the cable under test.

The problem to be solved lies in the fact that OPGW cable tests present uncertainty caused by: current measurement systems, data acquisition systems, electromagnetic interference caused by the electric arc of power, melting time of the striker filament, mechanism of Detection detection of the electric arc, mechanism of the measurement of the arc time, all the above impacts on the quality of the estimation of the test parameters such as the electric charge and the duration of the electric arc.

Some related works have been published: For example, patent US 8,040,517 B1 presents the invention of an arc detector system and method for simultaneously detecting an optical signal and an acoustic signal by means of a semi-transparent diaphragm placed in front of an array of optical fibers.

On the other hand, the patent US 8,319,173 B2 presents the invention of an arc protection that automatically monitors the state of optical detectors through the periodic and momentary transmission of optical signals.

Additionally, the patent 5,852,278 presents the invention of an arc welder using a high voltage source in direct current and a second source for the control thereof.

The Spanish patent ES 2434026T3 dated August 28, 2013 requested by General Electric Company, refers to the detection of electric arcs, or arc discharges and in particular to electric arc sensors. The document claims a sensor for simultaneously detecting light and acoustic waves, the sensor comprising one or more optical fibers, a diaphragm, arranged near one end of at least one of the one or more or optical fibers, the one or more being configured optical fibers for transmitting light from a light source on the diaphragm and for receiving a ray a beam of light reflected on the diaphragm, and the diaphragm being configured to vibrate before the incidence of acoustic waves coming from an electric arc and a semi-transparent zone arranged around the one or more optical fibers to diffuse the light originated by the electric arc towards at least one of the one or more optical fibers, wherein the one or more of the optical fibers, have the ability to transmit the light generated by an electric arc towards a detection system.

The aforementioned patents do not present an equipment or methods of an electric arc generator with direct regulated current constituted by: a three-phase power converter, which converts alternating current to direct current in a controlled manner according to the test parameters; a control unit, for regulation of said direct test current; where a current sensor performs the measurement of the direct current in the electric arc and feeds back its value to said control unit; an optical sensor for the presence of electric arc that allows detecting the start and end of said electric arc, where from the start detection the time of application of said electrical current by means of said control module is counted; where an array of electrodes, allows closing the circuit of said electrical current through a fusible element to establish the electric arc controlled by said control unit.

From the review of the state of the technology determines that none of the documents found in the state of the art solves the problems posed by itself.

The solution to the problem of having arcs with regulated current is an electric arc generator equipment regulated in direct current with functionality to perform automated remote control tests and the method to perform reliable tests, where optical detection and a method for the detection of the presence of an electric arc by optical fiber, as well as the estimation of real time duration of the test.

Objectives of the invention: Provide an electric arc generating equipment with regulated direct current consisting of: a three-phase power converter, which transforms alternating current to direct current in a controlled manner according to the test parameters; a control unit, for regulation of said direct test current; a current sensor that measures the direct current in the electric arc and feeds back its value to said control unit; an optical sensor of presence of electric arc allows to detect the start and the termination of said electric arc, where from the detection of the beginning the time of application of said electrical current by means of said control module is counted; an arrangement of electrodes that allows closing the circuit of said electrical current through a fusible element to establish the electric arc controlled by said control unit.

Another object of the present invention is to provide a method for the optical detection by optical fiber of the presence of electric arc, by means of an electric arc generating equipment with regulated direct current, comprising the steps of: placing an optical fiber in front of the electrode array where the electric arc is generated; wherein the light signal generated by the arc is transferred through said optical fiber to an optical-electric transducer; which detects the optical signal and the transducer converts said signal to an electrical signal; the electrical signal is compared to a predetermined level; and a result is generated with said comparison.

Another object of the present invention is to provide a control method for the generation of electric arc in direct current regulated as a function of time, which comprises the steps of: acquiring the three-phase AC voltage and current signals, voltage and DC current of the electric arc; calculate by a transformation of the input voltages an angle representative of the system, which is synchronized with the three-phase system; where the control action calculates the error between the desired current and the actual test current; processing said angle of the system and said error through the control logic for the generation of the pulses of shots for the control of the power converter; where the electrical signal generated by the electro-optical transducer coming from the light generated by the electric arc, is compared with a defined threshold for the detection of arc start where the comparison favors the activation of an electric arc time counter and of an integrator of the test stream; comparing the time counter against the defined test time and the test current integrator against an established electric charge value; and deactivating the generation of control pulses when any of the comparison conditions is met.

Another object of the present invention is to provide a method for the protection of the electric arc generator in regulated direct current comprising the steps of; acquisition of voltages and supply currents of the electric arc generator; the determination of system synchrony; measuring the amplitude values of the supply voltages of the electric arc generator; the comparison of the signals of the supply voltages against a defined threshold; the measurement of the input current intensity values of the electric arc generator; the comparison of the signals of the input currents against a defined threshold and the activation of the alarm signals with the results of the comparisons.

Brief description of the figures Figure 1 is a block diagram with the modules and instruments that make up the electric arc generator. 5 Figure 2 shows a block diagram containing the integral components of the power converter module.

Figure 3 is a block diagram with the modules, signal flow and data embedded in the equipment control unit to generate electric arcs regulated in direct current.

Figure 4 is a block diagram containing the modules that integrate the electro-optical mechanism for the detection of the electric arc. fifteen Figure 5 shows the state of the art with respect to the measurement of the load in the tests of arc to cables.

Figure 6 shows the procedure to correctly measure the electrical load 0 applied to the object under test.

Detailed description of the invention Figure 1 is a block diagram with the modules and instruments that integrate the electric arc generator (10), where (11) is a module of voltage signal conditioning of the power supply, (12) is the power converter with its complementary elements, (13) is the signal conditioning module of the output of the arc generator, (14) is the source DC power supply for electronics and control unit (1002), (15) is the RF-Ethernet communication unit, (16) is the cooling system of the power converter, electronics and control unit, (17) is the non-volatile storage unit and visualization, finally (18) is the electro-optical mechanism for the detection and measurement of the electric arc.

Figure 2 shows a block diagram containing the integrating components of the power converter module (12), where (121) is the system of fuses and suppressors of side peaks of the network, (122) is the controllable actuator of connection and disconnection of the power converter, (123) is the driver driver of (122), (124) is the filter of the side of the network, (125) is the Buck power converter, (126) is the driver circuit for the activation of the switches of the power converter, (127) is the module of coupling and conditioning of the control signals and trigger pulses from the control unit (20), (128) is the protection module of the bus of CD and (129) is the module for the download and control of the CD bus.

Figure 3 is a block diagram with the modules, signal flow and data embedded in the control unit (20) of the equipment to generate electric arcs regulated in direct current (10), where (11) is a conditioning module of signals, (15) is an Ethernet communications module, (17) is a storage module in a non-volatile memory, (1202) is the digital control pulses, (251) is a digital filter, (252) is a module for the calculation of the three-phase system angle, (253) is a comparator module to generate the modulation of digital pulses, (254) is a permissive selector for the generation of pulses, (255) is a module to generate the electrical pulses in digital card, (256) is a proportional-integral controller module which has a carry cleaning signal (1004) to prevent overflow of the control action, (257) is a module for the calculation of the control angle, (258) is a light intensity threshold comparator module, (259) is a module for the detection of the start of the electric arc, (260) is a module of initialization of the arc start time counter, (261) is an arc time counter, (262) is a module that completes the arc time counter based on the established test time, (263) is a module that concatenates in a block of memory the values of the monitored signals, where (1003) is a selector of signals to be displayed, (264) is a module for calculating electrical load and RMS value of the monitored signals, (265) is a module of storage in non-volatile memory and (266) is a module for data transmission per communications protocol.

Figure 4 is a block diagram containing the modules that integrate the electro-optical mechanism for the detection of the electric arc where (181) is the optical means to transmit the light flash coming from the electric arc (4), (182) is the opto-electronic detector and (183) is the electronic system composed by a controllable gain amplifier and a threshold detector, which sends an electrical signal (1801) to the control unit (20).

Best method of carrying out the invention In Figure 1 showing the electric arc generator equipment (10) are the functional modules that make up the equipment for the generation of electric arcs regulated in direct current described below. The electrical power supply of the electric arc generating equipment (10) comes from a three-phase power supply (1), where (11) is a module for signal conditioning and AC voltage measurement of the power supply of the power source. power (1), which conditions the high voltage levels of the source at levels manageable by the control system (20) without losing the waveform, frequency and phase of the signals. The three-phase power supply (1) is connected directly to the power converter unit type BUCK (12), the power converter rectifies the alternating current from the three-phase power supply (1) and transforms it into current direct (3) that is sent to the arc generator (10) At the output of the power converter module (11) is the direct current signal conditioning module (13) that is used for measurement and monitoring of the DC voltage and current levels of the output. For the energization of the electronic units and of the control unit (20) necessary for the operation of the arc generator (10), a power supply (14) is used. The communication of the control unit (20) with the remote control systems is carried out by means of the wired or wireless communication unit - such as the use the Ethernet communication protocol-, (15). The module (16) corresponds to the cooling module used to maintain the power elements of the power converter (12) at the optimum operating temperature. The data and the results obtained during the generation of electric arcs are stored and displayed in the non-volatile storage and display unit (17) that receives the measurement and monitoring information from the control unit (20). The arc generating equipment (10) obtains from the electro-optical mechanism (18) the electro-optical signal for the detection and measurement of the electric arc.

Figure 2 shows a block diagram containing the integral components of the power converter module (12), the operation and operation is explained below. The power supply source (1) is connected to the power converter module through the network side protection module (121) which performs the function of protecting and safeguarding the physical integrity of both the arc generator (10) and the generator (10). Power supply source (1). The energy that passes through the protection module is connected and disconnected from the power system using a controllable switch (122) that is operated by a handler (123) that receives the control signal (1201) from the control unit (20). ). A filter (124) is connected to the input of the power converter (125) to eliminate harmonics and electrical noise generated by the switching process of the power elements. The power converter type BUCK (125) is responsible for converting the alternating current into direct current and regulating the output current, corresponding to the control signals (1202) from the control unit (20), through a control signal coupling and conditioning module (127). At the output of the power converter there is the mu protection module of the CD bus (128) and (129) which is the module for the download and control of the CD bus.

In Figure 3 showing the control unit (20) are embedded the functional modules that make up the method for the generation of electric arcs regulated in direct current described below. The three-phase reference signal (1101) is applied to the low-pass digital filter (251). The output signals of this filter are applied to the module that performs the calculation of the system angle (252), this algorithm processes the three reference voltage signals using the first Park transform and generates two values corresponding to the magnitude and angle of the system three-phase The current signal in DC is applied to the proportional-integral (256) controller module, the controller is tuned to generate a reference value that compensates for the error of the expected DC current value. This reference value is applied to the module for the calculation of the control angle (257). The values of the angles obtained in (252) and (257) are applied to the comparator module to generate the modulation of digital pulses (253), which generates the correct sequence of the six digital pulses based on the angles of the system and control. The voltage signal coming from the optical sensor is applied to the light intensity threshold comparator module (258), in which it is compared if the value set as threshold is exceeded, enables a flag in logic state 1 that is sent to the module for the detection of the start of the electric arc (259), and the initialization of the time counter of start of arc (260), the initialization of the counter enables the permissive that indicates the establishment of the electric arc when its value is 1 and disables the generation of pulses when its value is 0. The arc time counter module (261) is increased as long as the value obtained from the module (258) is 1, this counter is compared with the test time and when they are equal, the arc time counter is terminated based on the established test time (262). Once the electric arc has been established and the arc start time counter (260) is enabled, the permissive selector is enabled for the generation of pulses (254), this selector compares the permissive selector given by (260) and (262) for the generation of digital pulses from the module (253). These digital pulses are applied to the module to generate the electrical pulses in digital card (255), which can generate them at a voltage level TTL or variable voltage if it receives power from an external CD voltage source. The signals used in the control process and other monitored signals are applied to the module that concatenates in a block of memory the values of the monitored signals (263), this block of memory is applied to the electrical load calculation module and RMS value of the monitored signals (264). The calculated values and the values of the signals contained in the memory block are stored in files by the non-volatile memory storage module (265), all these data are applied to the data transmission module by communication protocol (266) , to be displayed graphically in the Human-Machine Interface of the system.

Figure 4 shows the electro-optical mechanism (18) for block diagram detection containing the modules that integrate the electro-optical mechanism for the detection of the electric arc described below. The electro-optical signal (4) coming from the luminous flash of the generated electric arc is transmitted using an optical medium (181) to the detecting unit (182). The opto-electronic detector (192) is the unit that is responsible for converting the optical signal into an electrical signal manageable by the electronics of the instrumentation and the signal conditioners (193). The signal conditioning system (193) is the electronic system composed of a controllable gain amplifier and a threshold detecting that handles the signal provided by (192) by sending the signal with manageable electrical levels to the control unit (20).

Figure 5 shows by means of a graph (50) the state of the art with respect to the measurement of the load in the tests of arc to cables. This method does not contemplate the melting time of the filament nor the detection of arc initiation and therefore contains a percentage of error in the estimation of the electric charge (Coulombs) applied to the cable under test. a) The graph (50) typical of a test is shown, in which the test command that marks the beginning of the test is sent, at that moment it starts the generation of direct current (51) and after passing the time set by the user that is the period of time that elapses between (52) and (53), the current generation ends and the action is executed to finish said test. b) Once the current generation (54) of the test is started, the time set for the test is elapsed, the time elapsed between the points (55) and (56) and the generation of the current is completed. This method does not contemplate the melting time of the filament, nor the detection of 5 arc start. c) With the start of the test current generation (57), it starts calculating the electric charge (58) (Coulombs) and finishes integrating the current in time when it stops generating said current (59). This method does not contemplate the melting time of the filament, which leads to a percentage error in the measurement of the electric charge.

The device used to measure the melting time of the fuse and the duration of the electric arc is formed by a polymeric optical fiber, connected to a photosensitive element. With this device it is possible to distinguish the difference 15 between the light emitted during the fusion of the fusible conductor and the light emitted by the arc after the fuse has blown.

Figure 6 shows the procedure to correctly measure the electrical load applied to the object under test. 0 a) The graph (60) typical of a test is shown, in which the test command (61) that marks the start of the test is sent (62), at that moment the direct current generation begins and after passing the time set by the user, the current generation ends (63) and the action is executed to finish said test. b) (64) Once the generation of the test current (65) has started, there passes a time (66) in which the fusion of the filament (67) takes place, the Gual gives rise to the electric arc and later it is counted the time set for the test and finally the current generation (71) is interrupted and therefore the electric arc ends. c) The optical detector monitors the light intensity (68) that indicates the beginning of the arc, this arc light only occurs once the filament has melted, with this technique allows us to discriminate the melting time of the filament (69) and apply the electric arc effectively during the time defined for the test (70). d) With the start marked by the optical detector (73) the current is integrated only during the time that there is an established arc (74) and (75), which allows us to calculate in a very precise way the electric charge (Coulombs ) applied to the cable under test, discriminating the current used for the fusion of the fuse.

The measurement of the fusion time with optical techniques is very useful because it allows to determine graphically the time it takes to melt the fuse allowing applying the test current during the time required by the standard to the cable under test.

The material of the fusible conductor is one of the factors that determine the fusion time because each material has a specific melting coefficient. With this technique it is not necessary to know the physical characteristics of the material of the fuse or perform approximate calculations to determine the melting time with respect to the current, but simply measured and subtracted from the total test time. 5 It should be understood by all those experts in the field, that any change in form and detail, will be included in the spirit and scope of it.

Claims (13)

1. Electrical arc generating equipment with regulated direct current, characterized in that the device used to measure the melting time of the fuse and the duration of the electric arc is formed by a polymeric optical fiber, connected to a photosensitive element.

2. Electric arc generating equipment with regulated direct current as claimed in claim 1, wherein the equipment is constituted by: a) Three-phase power converter, which converts the alternating current to direct current in a controlled manner according to the test parameters , b) Control unit, for regulation of said direct test current, c) Current sensor, for the measurement of the direct current in the electric arc and feedback its value to said control unit, d) Electric arc presence optical sensor, to determine the start and end of said electric arc after accounting for the time of application of said electric current by means of said control module, e) Arrangement of electrodes, to close the circuit of said electric current through a fusible element and establish the electric arc controlled by said control unit.

3. Electric arc generating equipment with regulated direct current according to claim 2, wherein the control unit for the regulation of the test current containing the synchronization device with the three-phase system.

4. Electric arc generating equipment with regulated direct current according to claim 2, wherein the control unit for the regulation of the test current containing the generator of pulse pulses for control of the power converter.

5. Electric arc generating equipment with regulated direct current according to claim 2, wherein the control unit for the regulation of the test current containing the integrating device of the test current.

6. Electric arc generating equipment with regulated direct current according to claim 2, wherein the electric arc presence optical sensor contains the device for the detection of electric arc start.

7. Electric arc generator equipment with regulated direct current according to claim 2, wherein the control unit for the regulation of the test current containing the protection devices of current, voltage and time.

8. Electric arc generating equipment with regulated direct current according to claim 2, wherein the optical sensor for the presence of electric arc constituted by an optical fiber that uses the numerical aperture as a mechanism for detecting the presence of light generated by the electric arc. Electric arc.

9. Optical detection method using optical fiber for presence of arc 20 electric in electric arc generator equipment with regulated direct current, consisting of the following steps: a) Place the optical fiber in front of the electrode array where the arc is generated. b) Transfer of light signal generated by the arc through the optical fiber to an optical-electric transducer. c) Detecting the optical signal by the optical-electric transducer. d) Compare the electrical signal resulting from the optical-electrical conversion with a predetermined level. e) Notify the result of the comparison.

10. Method for direct optical detection of the presence of electric arc in electric arc generator equipment with regulated direct current, consisting of the following steps: a) Place the optical-electric transducer in front of the electrode array where the arc is generated. b) Detecting the optical signal by the optical-electric transducer. c) Transfer of electrical signal generated by the optical-electric transducer. d) Compare the electrical signal resulting from the optical-electrical conversion with a predetermined level. e) Notify the result of the comparison.

11. Control method for the generation of electric arc in direct current regulated as a function of time, which comprises the steps: to. Acquire from voltage signals, three-phase AC current and voltage, current in DC. b. Calculation of the angle of the system and synchronization with the three-phase system c. Calculation of the error and the control action of the test current against the desired current. d. Process of the control logic for the generation of the pulses of shots to control the power converter based on the angle of the system and the control action. and. Acquire the electrical signal generated by the electric optical transducer from the light generated by the electric arc, F. Detecting the start of the arc based on the comparison of the electrical signal of the optical transducer with a defined threshold. g. Activate electric arc timer. h. Compare from time counter against the defined test time i. Deactivate the generation of control pulses based on the comparison of the timer.

12. Control method for the generation of electric arc in direct current regulated as a function of the electric charge, which comprises the steps: to. Acquire from voltage signals, three-phase AC current and voltage, current in DC. b. Calculate the angle of the system and synchronization with the three-phase system c. Calculate the error and the control action of the test current against the desired current. d. Process the control logic for the generation of the pulses of shots to control the power converter based on the angle of the system and the control action, and. Acquire of the electrical signal generated by the electric optical transducer coming from the light generated by the electric arc, F. Detect of arc start based on the comparison of the optical signal of the optical transducer with defined threshold, g. Activate the electric current integrator. h. Compare the integration of the current against the desired electric charge, i. Disable pulse generation control based on comparison current integration.

13. Protective method of the electric arc generator in regulated direct current comprising the steps: to. Acquire from the voltages and power currents of the electric arc generator. b. Determine the synchrony of the system. c. Determine the amplitude values of the power supply voltages of the electric arc generator d. Compare the signals of the supply voltages against a defined threshold and. Determine the input current intensity values of the electric arc generator F. Compare the signals of the input currents against a defined threshold g. Activate the alarm signals with the results of the comparisons.