High-voltage box, battery cluster, and energy storage system

Abstract

The present application discloses a high-voltage box, a battery cluster, and an energy storage system. The high-voltage box comprises a first interface, a second interface, a third interface, a fourth interface, a first fuse, and a main control module. The third interface is electrically connected to a battery pack sequentially by means of the first fuse and the first interface. Two ends of the second interface are electrically connected to a battery pack and the fourth interface, respectively. The main control module comprises a voltage acquisition module. One end of the voltage acquisition module is electrically connected to a first node, and the other end of the voltage acquisition module is electrically connected to a second node.

Description

High-voltage box, battery cluster and energy storage system

[0001] The present application claims priority to the Chinese patent application No. 202422322598.8, filed on September 23, 2024, to the Chinese Patent Office, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of energy storage, in particular to a high-voltage box, a battery cluster and an energy storage system. BACKGROUND

[0003] The high-voltage box is a device used in the power system, mainly for integrating and controlling various high-voltage components to ensure the safe operation of the system. In the energy storage system, the high-voltage box serves as an intermediate unit connecting the battery cluster and the converter, with functions such as voltage / current collection, contactor control and protection. At the same time, the high-voltage box also supports battery cell voltage and temperature collection, equalization management and alarm functions in the energy storage system. SUMMARY

[0004] However, the high-voltage box has poor accuracy in the high-voltage collection process of the energy storage system.

[0005] In a first aspect, the present application provides a high-voltage box, comprising:

[0006] A first interface, one end of the first interface being electrically connected to one end of a battery pack;

[0007] A second interface, one end of the second interface being electrically connected to the other end of the battery pack;

[0008] A first fuse, one end of the first fuse being electrically connected to the other end of the first interface to form a first node;

[0009] A third interface, electrically connected to the other end of the first fuse;

[0010] A fourth interface, electrically connected to the other end of the second interface to form a second node;

[0011] A main control module, comprising a voltage collection module, one end of the voltage collection module being electrically connected to the first node, and the other end of the voltage collection module being electrically connected to the second node.

[0012] In a second aspect, the present application further provides a battery cluster, comprising at least one battery pack and the high-voltage box provided in the first aspect.

[0013] In a third aspect, the present application further provides an energy storage system, comprising a busbar cabinet and at least one battery cluster provided in the second aspect;

[0014] One end of the third interface is electrically connected to the other end of the first fuse, one end of the fourth interface is electrically connected to the other end of the second interface, and the other end of the third interface and the other end of the fourth interface are both electrically connected to the bus chamber. Advantages

[0015] The high-voltage box provided in the application comprises a first interface, a second interface, a third interface, a fourth interface, a first fuse, and a master control module. One end of the first interface is electrically connected to one end of a battery pack. One end of the second interface is electrically connected to the other end of the battery pack. One end of the first fuse is electrically connected to the other end of the first interface to form a first node. The third interface is electrically connected to the other end of the first fuse. The fourth interface is electrically connected to the other end of the second interface to form a second node. The master control module comprises a voltage acquisition module. One end of the voltage acquisition module is electrically connected to the first node, and the other end of the voltage acquisition module is electrically connected to the second node. Thus, after the main positive fuse in the high-voltage box ages, the accuracy of high-voltage acquisition can be maintained, and the high-voltage acquisition can be accurately performed in normal working conditions or in fault working conditions, which is beneficial to the maintenance and troubleshooting of field operation personnel and greatly improves the reliability of the high-voltage box. BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 is a first schematic block diagram of a battery cluster provided in the application;

[0017] Fig. 2 is an equivalent circuit diagram of voltage acquisition provided in the application;

[0018] Fig. 3 is another equivalent circuit diagram of voltage acquisition provided in the application;

[0019] Fig. 4 is a second schematic block diagram of a battery cluster provided in the application;

[0020] Fig. 5 is a schematic block diagram of an energy storage system provided in the application.

[0021] BRIEF DESCRIPTION OF DRAWINGS

[0022] 100, battery cluster; 110, high-voltage box; 120, battery pack; 200, bus chamber; R1, pre-charge resistor; K1, disconnecting switch; KA1, first relay; KA2, second relay; KA3, pre-charge relay; FU1, first fuse; FU2, second fuse; Hall, Hall sensor; RW, shunt; B+, first interface; B-, second interface; P+, third interface; P-, fourth interface; M, first node; N, second node; MBMU, master control board; SBMU, master control board; VCMU, slave control board. Embodiments of the application

[0023] In some embodiments, as shown in FIG. 1, in the electrical design of the high-voltage box 110 of the energy storage system 10, a main control board SBMU is arranged in the high-voltage box 110, and the main control board SBMU is electrically connected to the first interface B+ and the second interface B- of the high-voltage box 110 to collect high voltage of the battery cluster 100 where the high-voltage box 110 is located. Among them, two voltage collection lines are arranged on the copper bars of the first interface B+ and the second interface B-, one voltage collection line is the power ground of voltage collection, which is usually arranged near the second interface B- of the high-voltage box 110, and the other voltage collection line has no relevant theoretical basis, but it is usually placed between the main positive relay and the main positive fuse.

[0024] Under normal working conditions, the resistance value of the main positive fuse is very small, usually in the order of milliohms, which accounts for a very small proportion compared with the line resistance and the internal resistance of the series battery pack. Therefore, in the series loop formed by the total voltage collection, the total voltage collected by the main control board SBMU is basically the total voltage of the battery.

[0025] However, as the main positive fuse ages and its resistance value increases, or in extreme cases, the main positive fuse is blown due to overload or short-circuit current in the loop, and the resistance value of the blown main positive fuse can reach the order of megohms. At this time, in the series loop of the high-voltage collection of the main control board SBMU, the voltage shared by the main positive fuse needs to be considered. As shown in FIG. 2, it can be calculated that the series battery voltage collected by the main control board SBMU is significantly smaller than the actual value, which is not the actual voltage of the series battery.

[0026] According to the voltage collection principle, the equivalent circuit of voltage collection is shown in FIG. 3. The resistance value of the main positive fuse in the aging or abnormal blowing condition can be represented by the resistance R2. Therefore, the voltage value V collected by the high-voltage collection is V = R3 / (R3+R2)*U, where R2=6 MΩ and R3=5.11 MΩ. At this time, V = 5.11 / (5.11+6)*U = 0.46U, which shows that the collected voltage value V is significantly different from the actual voltage U of the battery.

[0027] In some embodiments, the application provides a battery cluster 100, which sets the voltage collection point at the main positive fuse between the main positive fuse and the first interface B+, so that the accuracy of high-voltage collection can be maintained after the main positive fuse in the high-voltage box 110 ages. At the same time, the energy storage system 10 can accurately collect high voltage under normal working conditions or fault working conditions, which is beneficial to the maintenance and troubleshooting of field operation and maintenance personnel, and greatly improves the reliability of the high-voltage box 110.

[0028] Please refer to FIG. 4, which is a second schematic block diagram of the battery cluster 100 provided by the application.

[0029] As shown in FIG. 4, the application provides a high-voltage box 110, which comprises:

[0030] A first interface B+, one end of the first interface B+ being electrically connected to one end of the battery pack 120;

[0031] A second interface B-, one end of the second interface B- being electrically connected to the other end of the battery pack 120;

[0032] A first fuse FU1, one end of the first fuse FU1 being electrically connected to the other end of the first interface B+ to form a first node M;

[0033] A third interface P+, the other end of the first fuse FU1 being electrically connected to the third interface P+;

[0034] A fourth interface P-, the other end of the second interface B- being electrically connected to the fourth interface P- to form a second node N;

[0035] A master control module 111, comprising a voltage acquisition module 101, one end of the voltage acquisition module 101 being electrically connected to the first node M, and the other end of the voltage acquisition module 101 being electrically connected to the second node N.

[0036] In the embodiment, the high-voltage box 110 is provided with four interfaces, namely the first interface B+, the second interface B-, the third interface P+ and the fourth interface P-. The first interface B+ and the second interface B- are configured to be electrically connected to the battery pack 120 on the battery cluster 100 to realize the charging and discharging of the battery pack 120, and the third interface P+ and the fourth interface P- are configured to be electrically connected to a target device, which can be the busbar cabinet 200 or a storage power converter.

[0037] Meanwhile, the first fuse FU1, i.e. the main positive fuse, is arranged between the first interface B+ and the third interface P+, and the master control module 111, i.e. the master control board SBMU, of the battery management system is arranged in the high-voltage box 110. The master control module 111 is provided with the voltage acquisition module 101, which is configured to acquire the high voltage of the battery cluster 100. The voltage acquisition module 101 is provided with two voltage acquisition lines. One voltage acquisition line is arranged between the first fuse FU1 and the first interface B+, i.e. is electrically connected to the first node M, and the other voltage acquisition line is arranged between the second interface B- and the fourth interface P-, i.e. is electrically connected to the second node N. Therefore, after the main positive fuse in the high-voltage box 110 is aged, the accuracy of high-voltage acquisition can be maintained, and the storage power system 10 can accurately acquire the high voltage in both normal working conditions and fault working conditions, which is beneficial to the maintenance and troubleshooting of the field operation and maintenance personnel and greatly improves the reliability of the high-voltage box 110.

[0038] The high-voltage box 110 provided in the application comprises a first interface B+, a second interface B-, a third interface P+, a fourth interface P-, a first fuse FU1 and a master control module 111, one end of the first interface B+ is electrically connected to one end of the battery pack 120; one end of the second interface B- is electrically connected to the other end of the battery pack 120; one end of the first fuse FU1 is electrically connected to the other end of the first interface B+ to form a first node M; the third interface P+ is electrically connected to the other end of the first fuse FU1; the fourth interface P- is electrically connected to the other end of the second interface B- to form a second node N; the master control module 111 comprises a voltage acquisition module 101, one end of the voltage acquisition module 101 is electrically connected to the first node M, and the other end of the voltage acquisition module 101 is electrically connected to the second node N, so that the accuracy of high-voltage acquisition can be maintained after the main positive fuse in the high-voltage box 110 is aged, and the high-voltage acquisition can be accurately performed in the energy storage system 10 under normal working conditions or under fault working conditions, which is beneficial to the maintenance and fault elimination of field operation and maintenance personnel and greatly improves the reliability of the high-voltage box 110.

[0039] In some embodiments, as shown in FIG. 4, the high-voltage box 110 further comprises a second fuse FU2; wherein one end of the second fuse FU2 is electrically connected to the other end of the second interface B- to form the second node N; the other end of the second fuse FU2 is electrically connected to the fourth interface P-.

[0040] In this embodiment, the second fuse FU2 is a main negative fuse in the high-voltage box 110, and the main negative fuse is electrically connected to the second interface B- and forms the second node N, so that the accuracy of high-voltage acquisition can also be maintained after the main negative fuse is aged.

[0041] In some embodiments, as shown in FIG. 4, the high-voltage box 110 further comprises a Hall sensor Hall; wherein one end of the Hall sensor Hall is electrically connected to the other end of the first interface B+; the other end of the Hall sensor Hall is electrically connected to one end of the first fuse FU1 to form the first node M.

[0042] The Hall sensor Hall is a magnetic field sensor based on the Hall effect, widely used in industrial automation, automotive electronics, computers and information technology fields. Its working principle is that when an electric current passes through a thin sheet of semiconductor material, a potential difference is generated in the direction perpendicular to the current and the magnetic field, which is called the Hall effect. According to different application requirements, Hall sensors can be divided into various types, including linear Hall sensors, switch-type Hall sensors and magnetic resistance Hall sensors. Linear Hall sensors can output an analog voltage or current signal proportional to the magnetic induction strength, suitable for applications requiring continuous measurement of magnetic field changes; while switch-type Hall sensors are used to detect a specific magnetic field threshold and produce a switching action when the threshold is reached.

[0043] In the embodiment, the first node M is arranged between the Hall sensor Hall and the first fuse FU1. Since the Hall sensor Hall has no direct electrical connection with the high-voltage copper bar, the service life aging or device failure does not affect the high-voltage acquisition function of the main control board SBMU, so whether the first node M is located on the left side or the right side of the Hall sensor Hall, it has no effect on the high-voltage acquisition module 101 to perform high-voltage acquisition.

[0044] In some embodiments, as shown in FIG. 4, the high-voltage box 110 further comprises a shunt RW; wherein one end of the shunt RW is electrically connected to the other end of the second interface B-, so as to form a second node N; the other end of the shunt RW is electrically connected to one end of the second fuse FU2.

[0045] In the embodiment, in order to accurately acquire the voltage of the battery in the battery cluster 100, the second node N needs to be arranged between the shunt RW and the second interface B-. The shunt RW is an electronic device used for current measurement and control, and its main function is to generate a low-resistance path through a low-resistance resistor, thereby guiding part of the current to another point in the circuit, so that the shunt RW can expand the measurement range of the current meter, and is commonly used in large current detection applications, such as overcurrent protection, 4-20mA system and battery charging, etc. The working principle of the shunt RW is based on the principle that a voltage is generated across a resistor when a direct current flows through the resistor. When current flows through the shunt RW, a certain voltage drop will be generated across it. By measuring this voltage drop, the total current flowing through the entire circuit can be indirectly measured. For example, in a power battery PACK, the shunt RW is used to detect the current value flowing through it, which is usually monitored in the form of voltage conversion.

[0046] In addition, the shunt RW has various types and specifications, and common ones include manganese-nickel-copper alloy resistance rods and copper strips coated with a nickel layer. The rated voltage drop is generally 60mV, but it can also be made into different specifications such as 75mV, 100mV, 120mV, 150mV and 300mV according to needs. In addition, the shunt RW can also be divided into built-in and external types, and the built-in type is usually used for small devices, while the external type is suitable for situations that require to handle larger currents.

[0047] In some embodiments, as shown in FIG. 4, the high-voltage box 110 further comprises a first relay KA1 and a second relay KA2; wherein one end of the first relay KA1 is electrically connected to the other end of the first fuse FU1, and the other end of the first relay KA1 is electrically connected to the third interface P+; one end of the second relay KA2 is electrically connected to the other end of the second interface B-, and the other end of the second relay KA2 is electrically connected to the fourth interface P-.

[0048] In this embodiment, the first relay KA1 is the main positive relay in the high-voltage box 110, and the second relay KA2 is the main negative relay in the high-voltage box 110. The main positive relay and the main negative relay in the high-voltage box 110 play a crucial role in the battery system. The main positive relay and the main negative relay can be controlled by the battery management system through the vehicle controller. The control is used to control the on-off of the main circuit. For example, during the charging process, the battery management system is awakened, the pre-charge relay KA3 is turned on by the battery management system, and then the main positive relay is turned on and the pre-charge relay KA3 is turned off.

[0049] The main positive relay is mainly configured to control the switching of the circuit and convert low-voltage signals into high-voltage signals to control the switching of high-power electrical equipment. The working principle of the main positive relay is to use electromagnetic attraction. When the control circuit is powered on, the coil of the main positive relay generates a magnetic field, attracting and activating the mechanical structure to achieve switching action. In addition, the main positive relay also has the function of circuit protection, which can play an important protective role in the circuit. The main negative relay is mainly responsible for overload protection. When the current in the circuit exceeds the set rated value, the main negative relay will automatically disconnect the circuit to prevent excessive current from causing equipment damage or fire hazards. It measures the current size to determine whether it exceeds the rated value and takes measures to disconnect the circuit in time. Therefore, the main positive relay and the main negative relay in the high-voltage box 110 are responsible for switching control and overload protection of the circuit, respectively, which can ensure the safe operation of the battery system.

[0050] In some embodiments, as shown in FIG. 4, the high-voltage box 110 further includes a pre-charge circuit; one end of the pre-charge circuit is electrically connected to one end of the first relay KA1 and the other end of the first fuse FU1, respectively; the other end of the pre-charge circuit is electrically connected to the other end of the first relay KA1 and the third interface P+, respectively.

[0051] In this embodiment, the main function of the pre-charge circuit is to protect the battery and other electrical components by controlling the flow of current. Specifically, the pre-charge circuit can limit the charging current, avoid shock phenomena, reduce spark arcing, main relays, and control the voltage rise rate.

[0052] Specifically, in the high-voltage box 110, the pre-charge resistor is connected between the positive electrode of the battery and the positive relay of the battery, forming a series circuit. When the energy storage system 10 is turned on, the voltage of the battery begins to rise, and at this time the high resistance characteristic of the resistor will limit the flow of current, thereby slowing down the voltage rise rate.

[0053] The pre-charging circuit controls the slope of the charging current, so that the battery can slowly absorb electrical energy at the initial charging stage, avoiding the occurrence of impact phenomenon. This helps to protect the internal structure of the battery, prolong the service life of the battery, and improve the stability of the entire charging system. At the same time, the pre-charging process can also reduce the spark arc when the high-voltage relay is closed, avoid high-voltage impact damage to high-voltage components, and improve the safety of the high-voltage system. In addition, the pre-charging circuit can reduce the impact current when powered on, protecting key components such as the battery and the main relay.

[0054] In some embodiments, as shown in FIG. 4, the pre-charging circuit includes a pre-charging relay KA3 and a pre-charging resistor R1; one end of the pre-charging relay KA3 is electrically connected to the other end of the pre-charging resistor R1, and the other end of the pre-charging relay KA3 is electrically connected to the third interface P+, the other end of the first relay KA1 respectively; the other end of the pre-charging resistor R1 is electrically connected to one end of the first relay KA1 and the other end of the first fuse FU1 respectively.

[0055] Specifically, the pre-charging resistor R1 is a high-resistance element, and the role of the pre-charging resistor R1 is to control the voltage rise speed of the system by limiting the flow of current. In the energy storage high-voltage box 110, the principle of the pre-charging resistor R1 is to limit the charging current of the energy storage box during the pre-charging stage, to avoid the generation of electric arc or overcurrent due to excessive current, thereby protecting the safe operation of the battery and the power system.

[0056] In some embodiments, as shown in FIG. 4, the high-voltage box 110 further includes a disconnecting switch K1; wherein the first end of the disconnecting switch K1 is electrically connected to the other end of the first relay KA1, the second end of the disconnecting switch K1 is electrically connected to the other end of the second relay KA2, the third end of the disconnecting switch K1 is electrically connected to the third interface P+, and the fourth end of the disconnecting switch K1 is electrically connected to the fourth interface P-.

[0057] Specifically, the disconnecting switch K1 is an important electrical equipment, mainly used for breaking or closing the circuit in the case of voltage but no load current, to achieve the purpose of safety isolation. The main function of the disconnecting switch K1 is to isolate the live equipment from the equipment under maintenance, and to form a clear break, to ensure the safety of the maintenance personnel.

[0058] At the same time, in the double busbar wiring system, the disconnecting switch K1 can cooperate with the circuit breaker to complete the busbar switching operation under the condition of equipotential. In addition, the disconnecting switch K1 can also be used to connect and disconnect the no-load transformer, voltage transformer, surge arrester and small current circuit not exceeding 5A.

[0059] In some embodiments, as shown in FIG. 5, the present application further provides a battery cluster 100, which includes at least one battery pack 120 and a high-voltage box 110.

[0060] In the embodiment, the battery cluster 100 includes a plurality of battery packs 120, which can be battery pack 1, battery pack 2, …, battery pack n respectively, and a high-voltage box 110. The plurality of battery packs 120 are connected in series and electrically connected to the first interface B+ and the second interface B- of the high-voltage box 110. Each battery pack 120 is provided with a slave board VCMU, and the high-voltage box 110 is provided with a master board SBMU.

[0061] The master board SBMU supports battery state data processing, realizes management and control of charging and discharging of the battery cluster 100, supports cluster voltage and cluster current detection, supports real-time isolation acquisition and processing of a Hall sensor Hall, and also supports insulation detection function, opening and closing detection function, single cell SOC / SOH / SOE / SOP estimation, cluster SOE and SOH estimation, thermal management control function, active cold and hot management, data storage function, local storage of system running data, and system expansion function including multi-channel active / passive node output. In addition, the master board SBMU supports Bootloader upgrade or remote upgrade.

[0062] The slave board VCMU supports single cell voltage and single cell temperature monitoring, pole temperature monitoring, CAN communication function, automatic addressing function, active / passive balancing function, and DO and DI signal transmission function.

[0063] In some embodiments, as shown in FIG. 5, the application also provides an energy storage system 10, which includes a busbar cabinet 200 and at least one battery cluster 100; one end of the third interface P+ is electrically connected to the other end of the first fuse FU1, one end of the fourth interface P- is electrically connected to the other end of the second interface B-, and the other end of the third interface P+ and the other end of the fourth interface P- are both electrically connected to the busbar cabinet 200.

[0064] In the embodiment, the energy storage system 10 includes a plurality of battery clusters 100, a busbar cabinet 200, and a power conversion system (PCS). Each battery cluster 100 is provided with a high-voltage box 110, which can be high-voltage box 1, …, high-voltage box n. The busbar cabinet 200 is provided with a master board MBMU, which supports real-time data access and display function of the plurality of battery clusters 100, and also supports interval storage of data, overvoltage, undervoltage, overcurrent, overtemperature, pressure difference, temperature difference, temperature rise, and other alarms. In addition, the master board MBMU also supports protection, online insulation detection, fault detection, thermal management control and protection function, configuration function of network parameters and communication parameters, and remote upgrade function of BMS three-level program.

Claims

1. A high-voltage box (110), comprising: a first interface (B+) having one end electrically connected to one end of a battery pack (120); a second interface (B-) having one end electrically connected to the other end of the battery pack (120); a first fuse (FU1) having one end electrically connected to the other end of the first interface (B+) to form a first node (M); a third interface (P+) electrically connected to the other end of the first fuse (FU1); a fourth interface (P-) electrically connected to the other end of the second interface (B-) to form a second node (N); a master control module (111) comprising a voltage acquisition module (101) having one end electrically connected to the first node (M) and the other end electrically connected to the second node (N).

2. The high-voltage box (110) of claim 1, further comprising a second fuse (FU2); wherein one end of the second fuse (FU2) electrically connected to the other end of the second interface (B-) to form the second node (N), and the other end of the second fuse (FU2) electrically connected to the fourth interface (P-).

3. The high-voltage box (110) of claim 2, further comprising a Hall sensor (Hall); wherein, one end of the Hall sensor (Hall) electrically connected to the other end of the first interface (B+), and the other end of the Hall sensor (Hall) electrically connected to one end of the first fuse (FU1) to form the first node (M).

4. The high-voltage box (110) of claim 2, further comprising a shunt (RW); wherein one end of the shunt (RW) electrically connected to the other end of the second interface (B-) to form the second node (N), and the other end of the shunt (RW) electrically connected to one end of the second fuse (FU2).

5. The high-voltage box (110) of any one of claims 1-4, further comprising a first relay (KA1) and a second relay (KA2); wherein one end of the first relay (KA1) electrically connected to the other end of the first fuse (FU1), and the other end of the first relay (KA1) electrically connected to the third interface (P+); one end of the second relay (KA2) electrically connected to the other end of the second interface (B-), and the other end of the second relay (KA2) electrically connected to the fourth interface (P-).

6. The high-voltage box (110) of claim 5, further comprising a pre-charge circuit; wherein one end of the pre-charge circuit electrically connected to one end of the first relay (KA1) and the other end of the first fuse (FU1), respectively; and the other end of the pre-charge circuit electrically connected to the other end of the first relay (KA1) and the third interface (P+), respectively.

7. The high pressure tank (110) according to claim 6, wherein the pre-charge circuit comprising a pre-charge relay (KA3) and a pre-charge resistor (R1). One end of the pre-charging relay (KA3) is electrically connected to the other end of the pre-charging resistor (R1), the other end of the pre-charging relay (KA3) is respectively electrically connected to the third interface (P+), the other end of the first relay (KA1); the other end of the pre-charging resistor (R1) is respectively electrically connected to one end of the first relay (KA1), the other end of the first fuse (FU1).

8. The high-voltage box (110) according to claim 5, further comprising a disconnecting switch (K1); wherein The first end of the disconnecting switch (K1) is electrically connected to the other end of the first relay (KA1), the second end of the disconnecting switch (K1) is electrically connected to the other end of the second relay (KA2), the third end of the disconnecting switch (K1) is electrically connected to the third interface (P+), and the fourth end of the disconnecting switch (K1) is electrically connected to the fourth interface (P-).

9. A battery cluster (100) comprising at least one battery pack (120) and the high-voltage box (110) according to any one of claims 1-8.

10. An energy storage system (10) comprising a busbar cabinet (200) and at least one battery cluster (100) according to claim 9. wherein One end of the third interface (P+) is electrically connected to the other end of the first fuse (FU1), one end of the fourth interface (P-) is electrically connected to the other end of the second interface (B-), and the other end of the third interface (P+) and the other end of the fourth interface (P-) are both electrically connected to the busbar cabinet (200).

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