A high voltage cabinet integrating overload protection and automatic reset function

Abstract

The utility model discloses an integrated overload protection and automatic reset function's high voltage cabinet, it includes cabinet, circuit breaker subassembly, monitoring module and reset mechanism, be equipped with circuit breaker installation cavity and electrical connection cavity in the cabinet, and circuit breaker subassembly is fixed in installation cavity and is linked with wiring terminal, monitoring module includes overload detection unit, short -circuit detection unit and temperature detection unit, is connected with key node through sensing circuit respectively, reset mechanism includes drive assembly, mechanical link system and lock catch device, and drive assembly is transmission connection with mechanical link system, and mechanical link system is engaged with circuit breaker switch handle, and lock catch device cooperation locking mechanism realizes circuit breaker state control, the utility model discloses can real -time monitoring current, transient change and temperature rise etc. parameter, when the fault occurs, and fast cut off power, and after the fault is removed, automatic reset, significantly improve the security, stability and recovery efficiency of system.

Description

Technical Field

[0001] This utility model relates to the technical field of power distribution equipment, and in particular to a high-voltage switchgear that integrates overload protection and automatic reset functions. Background Technology

[0002] With the development of power systems, high-voltage switchgear, as a key piece of equipment in power transmission and distribution systems, has seen continuous improvement in its safety, stability, and intelligence. However, in practical applications, existing high-voltage switchgear still suffers from problems such as untimely response, simplistic protection mechanisms, and the need for manual intervention in fault recovery when facing electrical overload conditions. This leads to prolonged system downtime and affects the continuity of power supply.

[0003] A search revealed a safety high-voltage switchgear with publication number CN113036637B, published on September 6, 2022. This design achieves the switchgear's mobility by incorporating mechanical structures such as threaded rods, cylinders, lifting rods, and transmission rods within a linkage chamber, improving the convenience of equipment installation and maintenance. However, this solution primarily focuses on physical mobility and does not address overload protection and automatic reset functions for the electrical system. Therefore, in the event of an electrical overload or short circuit, manual power disconnection and reset are still required, failing to achieve rapid automatic power cut-off and restoration, posing safety hazards and operational inconvenience.

[0004] The aforementioned issues indicate that while current high-voltage switchgear and related auxiliary devices on the market have made some progress in mechanical structure optimization and remote operation, they still suffer from shortcomings in electrical protection, such as slow response, low automation, and reliance on manual intervention. Therefore, there is an urgent need for a high-voltage switchgear that integrates overload protection and automatic reset functions, capable of rapidly responding to electrical anomalies, automatically cutting off power, and automatically restoring power after the fault is cleared. This would improve system stability and intelligence, meeting the demands of modern power systems for high reliability and automated operation and maintenance. Utility Model Content

[0005] The purpose of this utility model is to provide a high-voltage switchgear that integrates overload protection and automatic reset functions to overcome the shortcomings of the existing technology.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A high-voltage switchgear integrating overload protection and automatic reset functions includes a cabinet, a circuit breaker assembly, a monitoring module, and a reset mechanism. The cabinet interior has a circuit breaker mounting cavity and an electrical connection cavity. The circuit breaker assembly is fixed within the mounting cavity and connected to terminals within the electrical connection cavity via wires. The monitoring module includes an overload detection unit, a short-circuit detection unit, and a temperature detection unit. Each detection unit is connected to key nodes within the circuit breaker assembly and the electrical connection cavity via sensing lines. The reset mechanism includes a drive assembly, a mechanical linkage system, and a locking device. The drive assembly is embedded in the top of the cabinet and is connected to the mechanical linkage system. The mechanical linkage system penetrates the mounting cavity and engages with the switch operating handle of the circuit breaker assembly. The locking device is located at the end of the mechanical linkage system and cooperates with the locking mechanism of the circuit breaker assembly.

[0008] The overload detection unit includes a current transformer and a signal amplification circuit. The current transformer is mounted on the input conductor of the circuit breaker assembly and connected to the control core of the monitoring module through the signal amplification circuit. The short circuit detection unit includes a Hall effect sensor and a filter circuit. The Hall effect sensor is fixed inside the electrical connection cavity and close to the terminal block. The temperature detection unit includes a thermistor array. The thermistor array is attached to the outer surface of the circuit breaker assembly and the conductive bar inside the electrical connection cavity.

[0009] The drive assembly includes an electromagnet, a return spring, and a guide sleeve. The electromagnet is fixed to the top of the cabinet and connected to the guide sleeve by bolts. The return spring is fitted inside the guide sleeve and located between the movable end of the electromagnet and the first end of the mechanical linkage system. The mechanical linkage system includes a first link, a second link, and a third link. The first end of the first link is hinged to the movable end inside the guide sleeve. The tail end of the first link is hinged to the first end of the second link via a pin. The tail end of the second link is hinged to the first end of the third link via another pin. The tail end of the third link is provided with a groove that matches the switch operating handle of the circuit breaker assembly.

[0010] The locking device includes a latch, a locking spring, and an unlocking electromagnet. The latch is slidably mounted on the end of the third link and is kept tensioned by the locking spring. The unlocking electromagnet is fixed to the outside of the third link and abuts against the tail end of the latch through a push rod. The unlocking electromagnet is connected to the control core of the monitoring module through a signal line.

[0011] A further preferred embodiment: the number of turns in the secondary winding of the current transformer is 100 to 200 times that of the primary winding, and the output terminal of the secondary winding is connected to the signal amplification circuit through a shielded cable. The signal amplification circuit adopts a differential amplifier structure and achieves signal conditioning through an operational amplifier.

[0012] A further preferred embodiment: the distance between the sensing surface of the Hall effect sensor and the wiring terminal is 3mm to 5mm, and the output terminal of the Hall effect sensor is connected to the control core of the monitoring module through a low-pass filter circuit, wherein the cutoff frequency of the low-pass filter circuit is set to 1kHz to 5kHz.

[0013] A further preferred embodiment: the thermistor array includes at least three NTC thermistors, which are connected in series via a flexible printed circuit board, and the output of the thermistor array is connected to the control core of the monitoring module via a multiplexer.

[0014] A further preferred embodiment: the movable end of the electromagnet is provided with a guide post, the guide post passes through the central hole of the return spring and slides in cooperation with the inner wall of the guide sleeve, and the gap between the outer diameter of the guide post and the inner diameter of the return spring is 0.5mm to 1mm.

[0015] A further preferred embodiment: the first link, the second link, and the third link are all made of aluminum alloy, and each link has a rolling bearing at its hinge point. The outer ring of the rolling bearing is fixedly connected to the link, and the inner ring is rotatably engaged with the pin.

[0016] A further preferred embodiment: the front end of the latch is provided with a tapered guide surface, and the rear end of the latch is provided with a groove that matches the push rod, and the free length of the latch spring is 1.5 to 2 times the travel of the latch.

[0017] The structure and implementation principle of this utility model are as follows: When an overload or short-circuit fault occurs in the electrical system, the current transformer in the overload detection unit senses the abnormal current and transmits the signal to the control core of the monitoring module through the signal amplification circuit. Simultaneously, the Hall effect sensor in the short-circuit detection unit detects the transient current change and transmits the signal to the control core through the filtering circuit. The thermistor array in the temperature detection unit monitors the temperature rise of the circuit breaker assembly and the conductor busbar in real time and transmits the data to the control core. The control core determines the fault type based on a preset threshold and issues a command to quickly disconnect the power supply to the circuit breaker assembly. At this time, the locking device... The locking tongue in the circuit breaker assembly is engaged with the locking mechanism of the circuit breaker assembly and remains in an open state under the action of the locking spring. When the fault is cleared, the control core of the monitoring module detects that all parameters have returned to normal. First, it controls the unlocking electromagnet to move, and its push rod pushes the locking tongue to move backward, thereby releasing the lock on the circuit breaker assembly. Then, it controls the electromagnet in the drive assembly to be energized, and its moving end moves downward against the elastic force of the reset spring. Through the mechanical linkage system, it drives the switch operating handle of the circuit breaker assembly to move upward, completing the automatic reset process. After the reset is completed, the electromagnet is de-energized, and the reset spring pushes the mechanical linkage system to reset and prepare for the next action.

[0018] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0019] 1. By setting up a multi-level monitoring module that includes current transformers, Hall effect sensors and thermistor arrays, key parameters such as current, transient changes and temperature rise in the electrical system can be acquired in real time, effectively improving the accuracy and response speed of fault detection.

[0020] 2. The reset mechanism, which combines electromagnetic drive and mechanical linkage, enables rapid disconnection and automatic reset of the circuit breaker components through precise mechanical transmission. The entire fault handling process can be completed without manual intervention, significantly shortening the system recovery time.

[0021] 3. The combined use of the locking device and the unlocking electromagnet ensures reliable locking of the circuit breaker components while enabling precise and controllable unlocking operations, avoiding safety hazards caused by malfunctions and improving the stability and reliability of the system. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0023] Figure 2 This is a schematic diagram showing the connection relationship between the monitoring module and the circuit breaker assembly of this utility model;

[0024] Figure 3 This is a schematic diagram of the drive assembly and mechanical linkage system of this utility model;

[0025] Figure 4 This is a schematic diagram showing the cooperation relationship between the locking device and the circuit breaker assembly of this utility model;

[0026] Figure 5 This is a schematic diagram showing the installation positions of the overload detection unit and the short circuit detection unit of this utility model;

[0027] Figure 6 This is a schematic diagram showing the arrangement and connection relationship of the temperature detection unit of this utility model.

[0028] The attached figures are labeled as follows:

[0029] 1. Cabinet; 2. Circuit breaker assembly; 3. Monitoring module; 4. Reset mechanism; 5. Circuit breaker mounting cavity; 6. Electrical connection cavity; 7. Overload detection unit; 8. Short circuit detection unit; 9. Temperature detection unit; 10. Current transformer; 11. Signal amplification circuit; 12. Hall effect sensor; 13. Filter circuit; 14. Thermistor array; 15. Flexible printed circuit board; 16. Multiplexer; 17. Drive assembly; 18. Mechanical linkage system; 19. Locking device; 20. Electromagnet; 21. Reset 21. Spring; 22. Guide sleeve; 23. First connecting rod; 24. Second connecting rod; 25. Third connecting rod; 26. Slot; 27. Locking tongue; 28. Locking spring; 29. ​​Unlocking electromagnet; 30. Push rod; 31. Guide post; 32. Rolling bearing; 33. Tapered guide surface; 34. Groove; 35. Shielded cable; 36. Differential amplifier; 37. Operational amplifier; 38. Low-pass filter circuit; 39. Terminal block; 40. Conductor bar; 41. Switch operating handle; 42. Locking mechanism; 43. Control core. Detailed Implementation

[0030] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0031] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. When the number of elements is referred to as "multiple," it can be any number of two or more. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0033] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings:

[0034] Please see Figure 1 This utility model provides a high-voltage switchgear integrating overload protection and automatic reset functions, including a cabinet 1, a circuit breaker assembly 2, a monitoring module 3, and a reset mechanism 4. The cabinet 1 has a circuit breaker mounting cavity 5 and an electrical connection cavity 6 inside. The circuit breaker assembly 2 is fixed inside the circuit breaker mounting cavity 5 and connected to the wiring terminals 39 in the electrical connection cavity 6 via wires. The monitoring module 3 includes an overload detection unit 7, a short-circuit detection unit 8, and a temperature detection unit 9. Each detection unit is connected to key nodes in the circuit breaker assembly 2 and the electrical connection cavity 6 via sensing lines. The reset mechanism 4 includes a drive assembly 17, a mechanical linkage system 18, and a locking device 19. The drive assembly 17 is embedded in the top of the cabinet 1 and is connected to the mechanical linkage system 18. The mechanical linkage system 18 passes through the circuit breaker mounting cavity 5 and engages with the switch operating handle 41 of the circuit breaker assembly 2. The locking device 19 is located at the end of the mechanical linkage system 18 and cooperates with the locking mechanism 42 of the circuit breaker assembly 2.

[0035] Please see Figure 2 and Figure 5 The overload detection unit 7 includes a current transformer 10 and a signal amplification circuit 11. The current transformer 10 is mounted on the input conductor of the circuit breaker assembly 2 and connected to the signal amplification circuit 11 via a shielded cable 35. The signal amplification circuit 11 adopts a differential amplifier 36 structure and uses an operational amplifier 37 to achieve signal conditioning. The short-circuit detection unit 8 includes a Hall effect sensor 12 and a filter circuit 13. The Hall effect sensor 12 is fixed in the electrical connection cavity 6 and close to the terminal 39. The distance between its sensing surface and the terminal 39 is 3mm to 5mm. The output terminal of the Hall effect sensor 12 is connected to the control core 43 of the monitoring module 3 via a low-pass filter circuit 38. The cutoff frequency of the low-pass filter circuit 38 is set to 1kHz to 5kHz. The temperature detection unit 9 includes a thermistor array 14, which is attached to the outer surface of the circuit breaker assembly 2 and the conductive bar 40 in the electrical connection cavity 6. The thermistor array 14 includes at least three NTC thermistors, which are connected in series through a flexible printed circuit board 15. The output terminal of the thermistor array 14 is connected to the control core 43 of the monitoring module 3 through a multiplexer 16.

[0036] Please see Figure 3The drive assembly 17 includes an electromagnet 20, a return spring 21, and a guide sleeve 22. The electromagnet 20 is fixed to the top of the cabinet 1 and connected to the guide sleeve 22 by bolts. The return spring 21 is fitted inside the guide sleeve 22 and is located between the movable end of the electromagnet 20 and the beginning end of the mechanical linkage system 18. The movable end of the electromagnet 20 is provided with a guide post 31, which passes through the central hole of the return spring 21 and slides in cooperation with the inner wall of the guide sleeve 22. The gap between the outer diameter of the guide post 31 and the inner diameter of the return spring 21 is 0.5 mm to 1 mm. The mechanical linkage system 18 includes a first link 23, a second link 24, and a third link 25. The first end of the first link 23 is hinged to the movable end inside the guide sleeve 22. The tail end of the first link 23 is hinged to the first end of the second link 24 via a pin. The tail end of the second link 24 is hinged to the first end of the third link 25 via another pin. The tail end of the third link 25 is provided with a groove 26 that matches the switch operating handle 41 of the circuit breaker assembly 2. The first link 23, the second link 24, and the third link 25 are all made of aluminum alloy, and each link has a rolling bearing 32 at its hinge point. The outer ring of the rolling bearing 32 is fixedly connected to the link, and the inner ring is rotatably engaged with the pin.

[0037] Please see Figure 4 The locking device 19 includes a locking tongue 27, a locking spring 28, and an unlocking electromagnet 29. The locking tongue 27 is slidably mounted on the end of the third link 25 and is kept tensioned by the locking spring 28. The front end of the locking tongue 27 has a tapered guide surface 33, and the rear end of the locking tongue 27 has a groove 34 that matches the push rod 30. The free length of the locking spring 28 is 1.5 to 2 times the stroke of the locking tongue 27. The unlocking electromagnet 29 is fixed to the outside of the third link 25 and abuts against the tail end of the locking tongue 27 through the push rod 30. The unlocking electromagnet 29 is connected to the control core 43 of the monitoring module 3 through a signal line.

[0038] Please see Figure 6 The thermistor array 14 is connected to the multiplexer 16 via the flexible printed circuit board 15, and the temperature data is transmitted to the control core 43 via the multiplexer 16. The arrangement of the thermistor array 14 ensures that it can monitor the temperature rise on the surface of the circuit breaker assembly 2 housing and the conductive busbar 40 in real time, thereby providing accurate data support for fault diagnosis.

[0039] The working principle is as follows:

[0040] When an overload or short-circuit fault occurs in the electrical system, the current transformer 10 in the overload detection unit 7 senses the abnormal current and transmits the signal to the control core 43 of the monitoring module 3 through the signal amplification circuit 11. At the same time, the Hall effect sensor 12 in the short-circuit detection unit 8 detects the transient current change and transmits the signal to the control core 43 through the filtering circuit 13. The thermistor array 14 in the temperature detection unit 9 monitors the temperature rise of the circuit breaker assembly 2 and the conductor bus 40 in real time and transmits the data to the control core 43. The control core 43 determines the fault type according to the preset threshold and issues a command to quickly disconnect the power supply of the circuit breaker assembly 2. At this time, the locking tongue 27 in the locking device 19 engages with the locking mechanism 42 of the circuit breaker assembly 2 under the action of the locking spring 28 and remains in the open state.

[0041] Once the fault is cleared, the control core 43 of the monitoring module 3 detects that all parameters have returned to normal. First, it controls the unlocking electromagnet 29 to move, causing its push rod 30 to push the locking tongue 27 backward, thus releasing the lock on the circuit breaker assembly 2. Then, it controls the electromagnet 20 in the drive assembly 17 to be energized. Its movable end overcomes the spring force of the return spring 21 and moves downward, driving the switch operating handle 41 of the circuit breaker assembly 2 upward through the mechanical linkage system 18, completing the automatic reset process. After the reset is complete, the electromagnet 20 is de-energized, and the return spring 21 pushes the mechanical linkage system 18 to reset, preparing for the next action.

[0042] Specific application scenarios:

[0043] When a power supply circuit experiences an abnormally high current due to a short circuit, the current transformer 10 and Hall effect sensor 12 quickly detect the abnormal signal and transmit the processed data to the control core 43 via the signal amplification circuit 11 and filter circuit 13. After analysis, the control core 43 determines it to be a short circuit fault and immediately issues a command to cut off the power supply to the circuit breaker assembly 2. Simultaneously, the locking tongue 27 in the locking device 19 locks the circuit breaker assembly 2 under the action of the locking spring 28 to prevent accidental reset. After the fault is cleared, the control core 43 detects that the current and temperature have returned to normal. It first activates the unlocking electromagnet 29, whose push rod 30 pushes the locking tongue 27 to release the lock. Then, it energizes the electromagnet 20 in the drive assembly 17, which, through the mechanical linkage system 18, drives the switch operating handle 41 to complete the automatic reset. The entire process requires no manual intervention, significantly shortening the system recovery time and ensuring the stable operation of the factory production line.

[0044] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. For those skilled in the art, several modifications and improvements can be made without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A high-voltage switchgear integrating overload protection and automatic reset functions, characterized in that: The system includes a cabinet (1), which has a circuit breaker mounting cavity (5) and an electrical connection cavity (6) inside. The circuit breaker assembly (2) is fixed in the circuit breaker mounting cavity (5) and connected to the wiring terminal (39) in the electrical connection cavity (6) through a wire. The monitoring module (3) includes an overload detection unit (7), a short circuit detection unit (8), and a temperature detection unit (9). Each detection unit is connected to the key nodes in the circuit breaker assembly (2) and the electrical connection cavity (6) through a sensing line. The reset mechanism (4) includes a drive assembly (17), a mechanical linkage system (18), and a locking device (19). The drive assembly (17) is embedded in the top of the cabinet (1) and is connected to the mechanical linkage system (18) for transmission. The mechanical linkage system (18) passes through the circuit breaker mounting cavity (5) and engages with the switch operating handle (41) of the circuit breaker assembly (2). The locking device (19) is located at the end of the mechanical linkage system (18) and cooperates with the locking mechanism (42) of the circuit breaker assembly (2).

2. The high-voltage switchgear with integrated overload protection and automatic reset function according to claim 1, characterized in that: The overload detection unit (7) includes a current transformer (10) and a signal amplification circuit (11). The current transformer (10) is mounted on the input wire of the circuit breaker assembly (2) and connected to the signal amplification circuit (11) through a shielded cable (35). The signal amplification circuit (11) adopts a differential amplifier (36) structure and achieves signal conditioning through an operational amplifier (37).

3. A high-voltage switchgear with integrated overload protection and automatic reset functions according to claim 1, characterized in that: The short circuit detection unit (8) includes a Hall effect sensor (12) and a filter circuit (13). The Hall effect sensor (12) is fixed in the electrical connection cavity (6) and close to the terminal block (39). The sensing surface of the Hall effect sensor (12) is arranged adjacent to the terminal block (39), and the output end of the Hall effect sensor (12) is connected to the control core (43) of the monitoring module (3) through the low-pass filter circuit (38).

4. A high-voltage switchgear with integrated overload protection and automatic reset function according to claim 1, characterized in that: The temperature detection unit (9) includes a thermistor array (14), which is attached to the outer surface of the circuit breaker assembly (2) and the conductive bar (40) in the electrical connection cavity (6). The thermistor array (14) includes at least three NTC thermistors, which are connected in series through a flexible printed circuit board (15). The output terminal of the thermistor array (14) is connected to the control core (43) of the monitoring module (3) through a multiplexer (16).

5. A high-voltage switchgear with integrated overload protection and automatic reset function according to claim 1, characterized in that: The drive assembly (17) includes an electromagnet (20), a return spring (21), and a guide sleeve (22). The electromagnet (20) is fixed to the top of the cabinet (1) and connected to the guide sleeve (22) by bolts. The return spring (21) is fitted inside the guide sleeve (22) and located between the movable end of the electromagnet (20) and the beginning of the mechanical linkage system (18). The movable end of the electromagnet (20) is provided with a guide post (31). The guide post (31) passes through the center hole of the return spring (21) and slides in cooperation with the inner wall of the guide sleeve (22).

6. A high-voltage switchgear with integrated overload protection and automatic reset functions according to claim 1, characterized in that: The mechanical linkage system (18) includes a first link (23), a second link (24) and a third link (25). The first end of the first link (23) is hinged to the movable end inside the guide sleeve (22). The tail end of the first link (23) is hinged to the first end of the second link (24) through a pin. The tail end of the second link (24) is hinged to the first end of the third link (25) through another pin. The tail end of the third link (25) is provided with a slot (26) that matches the switch operating handle (41) of the circuit breaker assembly (2). The first link (23), the second link (24) and the third link (25) are all made of aluminum alloy. Each link is provided with a rolling bearing (32) at its hinge point. The outer ring of the rolling bearing (32) is fixedly connected to the link, and the inner ring is rotatably engaged with the pin.

7. A high-voltage switchgear with integrated overload protection and automatic reset functions according to claim 1, characterized in that: The locking device (19) includes a locking tongue (27), a locking spring (28), and an unlocking electromagnet (29). The locking tongue (27) is slidably mounted on the end of the third link (25) and is kept in tension with the third link (25) by the locking spring (28). The front end of the locking tongue (27) is provided with a tapered guide surface (33), and the rear end of the locking tongue (27) is provided with a groove (34) that matches the push rod (30). The unlocking electromagnet (29) is fixed to the outside of the third link (25) and abuts against the tail end of the locking tongue (27) by the push rod (30). The unlocking electromagnet (29) is connected to the control core (43) of the monitoring module (3) through a signal line.

8. A high-voltage switchgear with integrated overload protection and automatic reset functions according to claim 1, characterized in that: The locking mechanism (42) of the circuit breaker assembly (2) cooperates with the latch (27) in the latching device (19).

9. A high-voltage switchgear with integrated overload protection and automatic reset function according to claim 1, characterized in that: The control core (43) of the monitoring module (3) is connected to the overload detection unit (7), short circuit detection unit (8), temperature detection unit (9), drive assembly (17) and latching device (19) respectively through signal lines.

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