CN220254189U - Photovoltaic box transformer substation monitoring device - Google Patents

Abstract

The utility model discloses a photovoltaic box transformer substation monitoring device, which comprises a central processing unit, wherein the input end of the central processing unit is connected with a first information acquisition module and a remote control unit, and the first information acquisition module is used for acquiring switching value information, direct current value information and electric value information of a photovoltaic box transformer substation; the output end of the central processing unit is connected with the comprehensive display unit; the input end of the comprehensive display unit is also connected with a PLC module, a PID module and a second information acquisition module; the output end of the comprehensive display unit is also connected with the input end of the background monitoring unit. The monitoring information obtained by the device disclosed by the utility model is more comprehensive, the faults of the transformer can be diagnosed through various data, the safety index of the box transformer is improved, and the box transformer is more comprehensively protected.

Description

Photovoltaic box transformer substation monitoring device

Technical Field

The utility model belongs to the technical field of new energy photovoltaic power generation, and relates to a photovoltaic box transformer substation monitoring device.

Background

In the field of photovoltaic power generation, the photovoltaic grid-connected inverter is developed towards high integration, and the integrated grid-connected boost tank transformer is generated under the background. The intelligent monitoring system for the photovoltaic box transformer substation is a core of the whole integrated grid-connected boost box transformer substation, and can be used for carrying out remote management and automatic monitoring on information (such as three-phase current, three-phase voltage, power, non-electric quantity protection, control and communication functions and the like on the high-low voltage side of the transformer) of the photovoltaic box transformer substation.

The information quantity that current photovoltaic case becomes intelligent monitoring device gathered is less, and to the protection of case change incomplete, can't realize the omnidirectional monitoring protection to the case change, leads to the safe operation index of case change lower.

Disclosure of Invention

The utility model aims to solve the problems that the intelligent monitoring device for the photovoltaic box transformer substation in the prior art has less information quantity and cannot realize the omnibearing monitoring of the box transformer substation, and provides the photovoltaic box transformer substation monitoring device.

In order to achieve the purpose, the utility model is realized by adopting the following technical scheme:

the photovoltaic box transformer substation monitoring device comprises a central processing unit, wherein the input end of the central processing unit is connected with a first information acquisition module and a remote control unit, and the first information acquisition module is used for acquiring switching value information, direct current value information and electric value information of a photovoltaic box transformer substation;

the output end of the central processing unit is connected with the input end of the comprehensive display unit;

the input end of the comprehensive display unit is also connected with a PLC module, a PID module and a second information acquisition module;

and the output end of the comprehensive display unit is connected with the input end of the background monitoring unit.

The utility model further improves that:

the first information acquisition module comprises an electric quantity acquisition unit, a switching value acquisition unit and a direct current quantity acquisition unit;

the output ends of the electric quantity acquisition unit, the switching value acquisition unit and the direct current quantity acquisition unit are connected with the input end of the central processing unit.

And the central processing unit is connected with the comprehensive display unit through RS 485.

And the PLC module and the PID module are connected with the comprehensive display unit through an RS485 port.

The second information acquisition module comprises relay protection equipment, and the relay protection equipment is used for processing signals of the voltage-current transformer.

The second information acquisition module further comprises a temperature and humidity controller and an ammeter, and the temperature and humidity controller and the ammeter are connected with the input end of the comprehensive display unit.

The output end of the integrated display unit is also connected with the input end of the optical fiber annular Ethernet communication unit, and the output end of the optical fiber annular Ethernet communication unit is connected with the input end of the background monitoring unit.

The optical fiber ring Ethernet communication unit comprises a ring network switch, wherein the ring network switch is connected with an optical cable terminal box, a plurality of optical cables are arranged on the optical cable terminal box, and the optical cable terminal box is connected with a background monitoring unit through the optical cables.

The remote control unit is used for controlling the opening and closing of the low-voltage circuit breaker and the ring main unit vacuum circuit breaker;

the switching-off coil control loop and the switching-on coil control loop of the low-voltage circuit breaker are connected with the output end of the remote control unit;

and the switching-off coil control loop and the switching-on coil control loop of the ring main unit vacuum circuit breaker are connected with the output end of the remote control unit.

The direct current collection unit is used for collecting transformer oil temperature signals and low-voltage cabinet ammeter signals;

the transformer oil temperature signal is connected with the input end of the direct-current acquisition unit through the oil temperature sensor;

and the ammeter signal of the low-voltage cabinet is connected with the input end of the direct-current collection unit through an ammeter 4-20mA terminal.

Compared with the prior art, the utility model has the following beneficial effects:

the utility model discloses a photovoltaic box transformer substation monitoring device, which is characterized in that switching value information, direct current value information and electric value information of a photovoltaic box transformer substation are acquired through a first information acquisition module and are transmitted to a central processing unit, the central processing unit controls the operation of the photovoltaic box transformer substation according to the acquired basic information, so that the photovoltaic box transformer substation can safely and stably operate, the monitoring protection of a circuit is realized according to the change of acquired electric value data, the information of a PLC (programmable logic controller) module, a PID (proportion integration differentiation) module and a second information acquisition module is acquired through the central processing unit, the omnibearing monitoring of the box transformer substation is realized, the monitoring information acquired by the device disclosed by the utility model is more comprehensive, the fault of a transformer can be diagnosed through various data, the safety index of the box transformer substation is improved, and the protection of the box transformer substation is more comprehensive.

Further, the comprehensive display unit is connected with the optical fiber annular Ethernet communication unit through an electric port, and transmits information to the background monitoring unit through optical fibers, so that the background monitoring unit can monitor the photovoltaic box transformer substation in real time.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present utility model and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a photovoltaic box-section intelligent monitoring system of the present utility model;

FIG. 2 is a schematic diagram of an electrical quantity acquisition unit according to the present utility model;

FIG. 3 is a schematic diagram of a switching value acquisition unit according to the present utility model;

FIG. 4 is a schematic diagram of a DC acquisition unit according to the present utility model;

FIG. 5 is a schematic diagram of a remote control unit according to the present utility model;

FIG. 6 is a schematic diagram of an integrated display unit according to the present utility model;

fig. 7 is a schematic diagram of a communication unit according to the present utility model.

Wherein: 1-an electric quantity acquisition unit; 2-a switching value acquisition unit; 3-a direct current quantity acquisition unit; 4-a remote control unit; 5-a central processing unit; 6-an integrated display unit; 7-PLC module; an 8-PID module; 9-relay protection equipment; 10-a temperature and humidity controller; 11-ammeter; 12-acquisition equipment; 13-a fiber ring ethernet communication unit; 14-a background monitoring unit.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. The components of the embodiments of the present utility model generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the utility model, as presented in the figures, is not intended to limit the scope of the utility model, as claimed, but is merely representative of selected embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the description of the embodiments of the present utility model, it should be noted that, if the terms "upper," "lower," "horizontal," "inner," and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, or the azimuth or the positional relationship in which the inventive product is conventionally put in use, it is merely for convenience of describing the present utility model and simplifying the description, and does not indicate or imply that the apparatus or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

Furthermore, the term "horizontal" if present does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. As "horizontal" merely means that its direction is more horizontal than "vertical", and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the embodiments of the present utility model, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" should be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

The utility model is described in further detail below with reference to the attached drawing figures:

referring to fig. 1, the embodiment of the utility model discloses a photovoltaic box transformer substation monitoring device, which comprises a central processing unit 5, wherein the input end of the central processing unit 5 is connected with a first information acquisition module and a remote control unit 4, and the first information acquisition module is used for acquiring switching value information, direct current value information and electric value information of a photovoltaic box transformer substation; the output end of the central processing unit 5 is connected with the comprehensive display unit 6; the input end of the comprehensive display unit is also connected with a PLC module 7, a PID module 8 and a second information acquisition module; the output end of the integrated display unit is also connected with the input end of the background monitoring unit 14.

Further, the first information acquisition module comprises an electric quantity acquisition unit 1, a switching value acquisition unit 2 and a direct current quantity acquisition unit 3;

the electrical quantity acquisition unit further includes: the current transformer is arranged at the low-voltage side of the transformer, provides alternating current signals for the central processing unit, and the electric quantity acquisition unit 1 is used for acquiring electric quantity information of the photovoltaic box transformer and transmitting the electric quantity information to the central processing unit;

the switching value acquisition unit 2 is used for acquiring switching value information of the photovoltaic box transformer substation and transmitting the switching value information to the central processing unit, and specifically comprises the following steps:

the switching value acquisition unit further includes: the gas relay is arranged on the transformer body and provides a gas pressure signal generated by decomposing the medium-voltage transformer oil for the switching value acquisition unit; the switching value acquisition unit further includes: the pressure release valve is arranged on the transformer body and provides a medium-voltage transformer pressure release signal for the switching value acquisition unit.

The switching value acquisition unit further includes: the oil level gauge is arranged on the transformer body and provides a transformer oil level signal of the medium-voltage transformer; the switching value acquisition unit further includes: the oil level temperature controller is arranged on the transformer body and provides a transformer oil temperature signal of the medium-voltage transformer for the switching value acquisition unit.

The switching value acquisition unit further comprises: the winding temperature controller is arranged on the transformer body and provides a medium-voltage transformer winding temperature signal for the switching value acquisition unit.

Further, the switching value acquisition unit further includes: the frame breaker is arranged on the low-voltage side of the transformer and provides a frame breaker state signal for the switching value acquisition unit.

Further, the switching value acquisition unit further includes: the smoke detector is arranged in the low-pressure chamber and the medium-pressure chamber, and provides smoke detection signals for the switching value acquisition unit.

Further, the switching value acquisition unit further includes: the surge protector is arranged in the low-voltage chamber and the power distribution cabinet, and provides a surge protector state signal for the switching value acquisition unit.

Further, the switching value acquisition unit further includes: and the temperature and humidity controller is arranged in the low-voltage chamber and the power distribution cabinet and provides an overtemperature alarm signal for the switching value acquisition unit.

Further, the switching value acquisition unit further includes: the travel switch is arranged on the box body and provides an access control signal for the switching value acquisition unit.

Further, the switching value acquisition unit further includes: the heat exchanger is arranged on the box body and provides a heat exchanger fault signal for the switching value acquisition unit.

Further, the switching value acquisition unit further includes: the relay protection device is arranged on the medium-voltage chamber ring main unit and provides ring main unit state signals for the switching value acquisition unit.

The direct current collection unit 3 is used for collecting direct current information of the photovoltaic box transformer substation and transmitting the direct current information to the central processing unit.

Further, the direct current collection unit further includes: PT100 platinum resistance, PT100 platinum resistance installs in oil level temperature controller, PT100 platinum resistance is for direct current volume acquisition unit provides medium voltage transformer oil temperature information.

Further, the direct current collection unit further includes: the ammeter is arranged in the power distribution cabinet, and the ammeter provides current and voltage analog quantity information of the power distribution cabinet for the direct current collecting unit.

Furthermore, in the utility model, the remote control unit 4 is used for remotely controlling the switching of the vacuum circuit breaker and the low-voltage frame circuit breaker of the medium-voltage ring main unit of the box transformer, and the central processing unit 5 controls the photovoltaic box transformer to work according to the received electrical quantity information, switching value information, direct current quantity information and remote control signals, so that the photovoltaic box transformer can safely and stably run.

Further, in the utility model, the electric quantity acquisition unit 1, the switching value acquisition unit 2, the direct current quantity acquisition unit 3 and the remote control unit 4 are all used for transmitting information to the comprehensive display unit 6 through electric connection after analog-digital conversion.

Further, in the utility model, the integrated display unit 6 is connected to the PLC module 7, the PID module 8 and the second information acquisition module through the RS485 port. The power-over port of the integrated display unit 6 is connected with the optical fiber annular Ethernet communication unit 13, and information is transmitted to the background monitoring unit 14 through optical fibers, so that the real-time monitoring of the photovoltaic box transformer substation by the background monitoring unit 14 is realized.

The embodiment of the utility model also discloses a connecting structure, wherein the integrated display unit 6 is connected with the PLC module 7 and the PID module 8 and is arranged in a communication cabinet, and the integrated display unit 6 is connected with the PLC module 7 and the PID module 8 through electric ports.

The comprehensive display unit 6 is connected with the relay protection device 9, and the comprehensive display unit 6 is connected with the relay protection device 9 through an RS485 bus mode.

Further, the integrated display unit 6 is connected with other devices through an RS485 bus, and the other devices include: and a temperature and humidity controller.

Further, the integrated display unit 6 is connected with a ring network switch through an ethernet cable, the ring network switch is connected with an optical cable terminal box through a double-core duplex single-mode LC optical fiber jumper, the optical cable terminal box is at least a 2-inlet 16-port terminal box, the fiber core capacity is 32, and the optical cable terminal box is connected with the background monitoring unit 14 through an optical cable.

Referring to fig. 2, further, in the present utility model, the electrical quantity acquisition unit 1 acquires three-phase current parameters, three-phase voltage parameters, frequency parameters, power factor parameters, active power parameters, reactive power parameters, and the like. The specific application is as follows:

the current transformers CT1, CT2 and CT3 are used for monitoring the current of the transformer, sending the current to the X6 module (electric quantity acquisition unit) to acquire three-phase current, the fuse type isolating switch F1, the voltage transformers PT1 and PT2 and the miniature circuit breaker QFB17 are used for monitoring the voltage of the transformer, sending the voltage to the X6 module (electric quantity acquisition unit) to acquire three-phase voltage to complete acquisition of electric quantity parameters, and the X6 module (electric quantity acquisition unit) is connected to the central processing unit.

Referring to fig. 3, in the present utility model, the switching value collection unit 2 collects a transformer light gas alarm signal, a transformer heavy gas trip signal, a transformer high temperature alarm signal, a transformer ultra-high Wen Tiaozha signal, a transformer oil level low alarm signal, a transformer pressure abnormal trip signal, a transformer winding high temperature alarm signal, a transformer winding high temperature trip signal, a breaker switch-on signal, a breaker switch-off signal, a breaker fault signal, a breaker local signal, a breaker remote signal, a UPS power supply loss signal, a smoke induction signal, a surge protector failure signal, an access control signal, a heat exchanger fault signal, a temperature and humidity controller overtemperature alarm signal, a high voltage breaker switch-on signal, a high voltage breaker switch-off signal, a high voltage isolation switch-on signal, a ground switch-off signal, a breaker non-energy storage signal, a remote position signal, a G1 high voltage load switch-on signal, a G1 ground switch-off signal, a G2 high voltage load switch-on signal, a G2 high voltage load switch-off signal, a G2 ground switch-off signal, and the like.

Specifically, a dry node of a transformer light gas alarm, a transformer heavy gas trip, a transformer high temperature alarm, a transformer ultrahigh Wen Tiaozha, a transformer oil level low alarm, a transformer pressure abnormal trip, a transformer winding high temperature alarm, a transformer winding high temperature trip, a breaker switch-on, a breaker switch-off, a breaker fault, a breaker on-site, a breaker remote place, a UPS power failure, smoke induction, a surge protector failure, an access control, a heat exchanger fault, a temperature and humidity controller over-temperature alarm is connected to an X4 module, a high-voltage breaker switch-on, a high-voltage breaker switch-off, a high-voltage isolation switch-on, a high-voltage isolation switch-off, a ground switch-on, a ground switch-off, a breaker non-energy storage remote position, a G1 high-voltage load switch-on, a G1 high-voltage load switch-off, a G1 ground switch-off, a G2 high-voltage load switch-on, a G2 ground switch-off is connected to an X7 module, and an X7 module is connected to a dry node of a switch-on, so as to complete a switching quantity parameter, and the X7 module is connected to a central processing unit. In this embodiment, the X4 module and the X7 module both represent a switching power collection unit.

Referring to fig. 4, the dc collection unit 3 collects a transformer oil temperature signal and a low-voltage cabinet ammeter signal.

Specifically, the transformer oil temperature signal is connected to an X2 module (direct current collection unit) through an oil temperature sensor, the low-voltage cabinet ammeter signal is connected to the X2 module (direct current collection unit) through an ammeter 4-20mA terminal, collection of direct current parameters is completed, and the X2 module (direct current collection unit) is connected to a central processing unit.

As shown in fig. 5, the remote control unit 4 is used for remotely controlling the opening and closing of the low-voltage circuit breaker and the ring main unit vacuum circuit breaker.

Specifically, the switching-off coil control loop and the switching-on coil control loop of the low-voltage circuit breaker are connected to an X3 module (remote control unit), the switching-off coil control loop and the switching-on coil control loop of the ring main unit vacuum circuit breaker are connected to the X3 module (remote control unit), and the X3 module (remote control unit) is connected to the central processing unit.

As shown in fig. 6, the central processing unit 5 is connected to the integrated display unit 6 through RS485, and the integrated display unit is used for performing monitoring communication with the background to complete information transmission.

Specifically, the PID module 8 can realize the lifting of the ground voltage of the alternating current side of the inverter, so that the ground voltage of the direct current side is also lifted, the photovoltaic module is free from negative bias to the ground, the PID effect inhibition is realized, and the PID module 8 is connected into the integrated display unit 6 through RS485 to complete information transmission.

Specifically, the PLC module 7 transmits the status information of the inverter to the PLC module 7 through a power carrier mode, and the PLC module 7 accesses the integrated display unit 6 through RS485 to complete information transmission.

Specifically, the relay protection device 9 processes signals from the medium voltage and current transformers by adopting a microprocessor with high integration level and low power consumption, and the relay protection device is connected to the comprehensive display unit 6 through RS485 to complete information transmission through the output of the digital logic operation control device.

Specifically, the temperature and humidity controller 10, the ammeter 11, any other devices such as the acquisition equipment 12 and the like access the acquired signals to the comprehensive display unit 6 through the RS485, and information transmission is completed.

As shown in fig. 6, when the integrated display unit 6 is in operation, the integrated display unit is connected with different units, modules or devices through RS485 to collect collected information, and the integrated display unit transmits information to the optical fiber annular ethernet communication unit 13 through an electrical port to complete information transmission.

As shown in fig. 6, the optical fiber ring ethernet communication unit 13 performs optical fiber communication with the optical cable terminal box through the ring network switch, and transmits the information collected by the integrated display unit to the background monitoring unit 14 through the optical cable, so as to complete information transmission.

As shown in fig. 7, the optical cable terminal box uses at least two optical cables, forms an optical ring network with the optical cable terminal boxes of different box transformer substation in a "hand-in-hand" manner, is connected to a station-level ring network switch, realizes background remote management and automatic monitoring, carries out real-time online omnibearing monitoring on the box transformer substation, improves system stability, and thereby improves the safety index of the box transformer substation.

The central processing unit in the device disclosed by the utility model can collect the electric quantity such as low-voltage side three-phase current, three-phase voltage, frequency, power factor, active power, reactive power, active power degree, reactive power degree and the like of the box transformer, and the non-electric quantity such as temperature, pressure, oil level, door state and heat exchanger fault signal of the box transformer, and can realize remote measurement of the running condition of the box transformer; meanwhile, remote control and protection of the circuit are realized through remote control of the box low-voltage side frame breaker and the ring main unit vacuum breaker; and secondly, the comprehensive display unit is used for accessing communication of external equipment such as a relay protection device and the like, remote signaling monitoring of electric energy of the ring main unit and the low-voltage cabinet is realized, all-round monitoring of the box transformer substation is realized, comprehensive, reliable and efficient control is carried out on the box transformer substation, conditions are created for 'unattended operation and less personnel' of the photovoltaic power station, and the safety index of the box transformer substation is improved.

The above is only a preferred embodiment of the present utility model, and is not intended to limit the present utility model, but various modifications and variations can be made to the present utility model by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.

Claims (10)

1. The photovoltaic box transformer substation monitoring device is characterized by comprising a central processing unit (5), wherein the input end of the central processing unit (5) is connected with a first information acquisition module and a remote control unit (4), and the first information acquisition module is used for acquiring switching value information, direct current value information and electric value information of a photovoltaic box transformer substation;

the output end of the central processing unit (5) is connected with the input end of the comprehensive display unit (6);

the input end of the comprehensive display unit (6) is also connected with a PLC module (7), a PID module (8) and a second information acquisition module;

the output end of the comprehensive display unit (6) is connected with the input end of the background monitoring unit (14).

2. The photovoltaic box-type substation monitoring device according to claim 1, wherein the first information acquisition module comprises an electrical quantity acquisition unit (1), a switching value acquisition unit (2) and a direct current quantity acquisition unit (3);

the output ends of the electric quantity acquisition unit (1), the switching value acquisition unit (2) and the direct current quantity acquisition unit (3) are connected with the input end of the central processing unit (5).

3. The photovoltaic box transformer substation monitoring device according to claim 1, characterized in that the central processing unit (5) is connected with the integrated display unit (6) through RS 485.

4. The photovoltaic box transformer substation monitoring device according to claim 1, characterized in that the PLC module (7) and the PID module (8) are connected with the integrated display unit (6) through RS485 ports.

5. The photovoltaic box transformer substation monitoring device according to claim 1, characterized in that the second information acquisition module comprises a relay protection device (9), wherein the relay protection device (9) is used for processing signals of a voltage-current transformer.

6. The photovoltaic box transformer substation monitoring device according to claim 5, wherein the second information acquisition module further comprises a temperature and humidity controller (10) and an ammeter (11), and the temperature and humidity controller (10) and the ammeter (11) are connected with the input end of the integrated display unit (6).

7. The photovoltaic box transformer substation monitoring device according to claim 1, wherein the output end of the integrated display unit (6) is further connected with the input end of the optical fiber ring-shaped ethernet communication unit (13), and the output end of the optical fiber ring-shaped ethernet communication unit (13) is connected with the input end of the background monitoring unit (14).

8. The photovoltaic box transformer substation monitoring device according to claim 7, characterized in that the optical fiber ring-shaped ethernet communication unit (13) comprises a ring network switch, the ring network switch is connected with an optical cable terminal box, a plurality of optical cables are arranged on the optical cable terminal box, and the optical cable terminal box is connected with a background monitoring unit (14) through the optical cable.

9. The photovoltaic box transformer substation monitoring device according to claim 1, characterized in that the remote control unit (4) is used for controlling the opening and closing of a low-voltage breaker, a ring main unit vacuum breaker;

the switching-off coil control loop and the switching-on coil control loop of the low-voltage circuit breaker are connected with the output end of the remote control unit (4);

and a switching-off coil control loop and a switching-on coil control loop of the ring main unit vacuum circuit breaker are connected with the output end of the remote control unit (4).

10. The photovoltaic box transformer substation monitoring device according to claim 2, wherein the direct current collection unit (3) is used for collecting transformer oil temperature signals and low-voltage cabinet ammeter signals;

the transformer oil temperature signal is connected with the input end of the direct current collection unit (3) through an oil temperature sensor;

the low-voltage cabinet ammeter signal is connected with the input end of the direct current collection unit (3) through an ammeter 4-20mA terminal.