A dual power supply automatic switching lockout control circuit

Abstract

The present invention belongs to the field of power supply technology application, and relates to a dual-power standby automatic re-entry lockout control circuit, comprising a DC power supply positive electrode +KM, a Q1 protection outlet tripping circuit, a Q2 protection outlet tripping circuit, a standby automatic re-entry lockout control circuit, and a DC power supply negative electrode -KM. The DC power supply positive electrode +KM is connected in parallel to the Q1 protection outlet tripping circuit, the Q2 protection outlet tripping circuit, and the standby automatic re-entry lockout control circuit, and returns to the DC power supply negative electrode -KM to form a loop. The present invention is simple and feasible to implement, does not require additional investment, and can achieve standby automatic re-entry when two high-voltage incoming power sources lose power or when a distribution transformer loses power, ensuring reliable power supply operation; and when a low-voltage busbar short-circuit fault causes the non-selective quick-break protection of the corresponding distribution transformer high- and low-voltage side circuit breaker to trip, it can effectively avoid the failure of the two busbar sections being completely powered off due to the erroneous closing and automatic re-entry of the low-voltage side bus tie circuit breaker Q, thereby ensuring safe and reliable power supply.

Description

Technical Field

[0001] The invention belongs to the field of power supply technology application, and in particular relates to a dual-power supply standby automatic switching locking control circuit. Background Art

[0002] In order to improve the reliability of power supply, most important high-voltage distribution users are powered by two power sources. To ensure reliable power supply, some users' terminal equipment is also equipped with automatic switching devices.

[0003] In the high-voltage power supply system, the 10kV I incoming line supplies power to the 0.4kV low-voltage busbar W1 via distribution transformer (hereinafter referred to as distribution transformer) T1 and circuit breaker Q1. The 10kV II incoming line supplies power to the 0.4kV low-voltage busbar W2 via distribution transformer T2 and circuit breaker Q2. The bus tie breaker for 10kV sections I and II is QF, and the bus tie breaker for 0.4kV low-voltage busbars W1 and W2 is Q. During normal power supply operation, the 10kV bus tie breaker QF and the 0.4kV bus tie breaker Q serve as hot standby, while all other circuit breakers are closed. To enhance equipment power supply reliability, a dual power backup automatic switching device is installed. When the 10kVⅠ (or Ⅱ) incoming line and distribution transformer T1 (or T2) fail and lose power, as long as the two conditions of "distribution transformer low-voltage relay kV loss" and "distribution transformer low-voltage side circuit breaker tripping" are met, the low-voltage bus tie circuit breaker Q standby automatic transfer will be automatically put into operation, and the 10kVⅡ (or Ⅰ) incoming line and distribution transformer T2 (or T1) will supply all loads of the low-voltage bus W1 (or W1) through the 0.4kV low-voltage bus tie circuit breaker Q to ensure safe, continuous and stable power supply for the entire power supply system.

[0004] However, in actual field applications, due to the design flaws in the principle of the bus tie circuit breaker automatic re-closing electrical circuit, for example, when a short circuit occurs on the low-voltage busbar W1 or busbar W2, due to the non-selective action of the protection, the high-voltage and low-voltage side circuit breakers of distribution transformers T1 and T2 will both trip and lose power. At this time, the backup automatic re-closing criteria will also be met, and the low-voltage bus tie circuit breaker Q will automatically re-close. In this case, power will be restored and then lost, causing greater repeated damage to the fault point and expanding the scope of the accident. Therefore, in order to improve the safety and reliability of equipment operation, it is necessary to provide a dual-power backup automatic re-closing lockout control circuit. Summary of the Invention

[0005] The object of the present invention is to provide a dual-power supply standby automatic switching lockout control circuit, which can realize standby automatic switching when two high-voltage incoming power sources fail or the distribution transformer fails, thereby ensuring reliable power supply operation; and when a low-voltage bus short-circuit fault causes the non-selective quick-break protection of the high- and low-voltage side circuit breakers of the corresponding distribution transformer to trip, it can effectively avoid the power outage of the two bus sections caused by the erroneous closing and automatic switching of the low-voltage side bus tie circuit breaker Q, thereby ensuring safe and reliable power supply.

[0006] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is as follows: the present invention provides a dual-power standby automatic transfer locking control circuit, including a DC power supply positive electrode +KM, a Q1 protection outlet tripping circuit, a Q2 protection outlet tripping circuit, a standby automatic transfer locking control circuit, and a DC power supply negative electrode -KM, wherein the DC power supply positive electrode +KM is connected in parallel to the Q1 protection outlet tripping circuit, the Q2 protection outlet tripping circuit, and the standby automatic transfer locking control circuit and returns to the DC power supply negative electrode -KM to form a loop;

[0007] The Q1 protection outlet tripping circuit includes a self-holding unlocking switch S1 and a self-holding contact K011 of the protection outlet relay K01, a normally open contact TJ1 of the protection tripping intermediate relay of the low-voltage circuit breaker Q1, and a normally open contact K012 of the protection outlet relay K01; the Q2 protection outlet tripping circuit includes a self-holding unlocking switch S2 and a self-holding contact K021 of the protection outlet relay K02, a normally open contact TJ2 of the protection tripping intermediate relay of the low-voltage circuit breaker Q2, and a normally open contact K013 of the protection outlet relay K01. The normally open contact K022 of the protection outlet relay K02; the standby automatic transfer locking control circuit includes the first group of contacts, the second group of contacts, the normally closed contacts of the low-voltage busbar circuit breaker automatic transfer device linkage switch SA, the normally closed contacts of the low-voltage relay KV1, the normally closed contacts of the low-voltage relay KV2, the second auxiliary normally closed contact Q12 of the low-voltage circuit breaker Q1, the second auxiliary normally closed contact Q22 of the low-voltage circuit breaker Q2, and the normally closed contacts of the protection outlet relay K01 and the normally closed contacts of the protection outlet relay K02.

[0008] Furthermore, the Q1 protection output tripping circuit also includes the first auxiliary normally closed contact Q11 of the low-voltage circuit breaker Q1 and the closing coil HQ1 of Q1, the Q2 protection output tripping circuit also includes the first auxiliary normally closed contact Q21 of the low-voltage circuit breaker Q2 and the closing coil HQ2 of Q2, the Q standby automatic transfer locking control circuit includes the auxiliary normally closed contact of the main circuit breaker Q and the closing coil HQ of Q, the first group of contacts of the low-voltage main circuit breaker automatic transfer device linkage switch SA includes contact a and contact b, and the second group of contacts of the low-voltage main circuit breaker automatic transfer device linkage switch SA includes contact c and contact d.

[0009] Furthermore, the self-holding unlocking switch S1 is connected in series with the self-holding contact K011 of the protection output relay K01 and then connected in parallel with the normally open contact TJ1 of the protection tripping intermediate relay of the low-voltage circuit breaker Q1. Then, the coil of the protection output relay K01 is connected in series, and then the first normally open contact K012 of the protection output relay K01, the first auxiliary normally closed contact Q11 of the low-voltage circuit breaker Q1 and the closing coil HQ1 of the low-voltage circuit breaker Q1 are connected in parallel.

[0010] Furthermore, the self-holding unlocking switch S2 is connected in series with the self-holding contact K021 of the protection output relay K02 and then connected in parallel with the normally open contact TJ2 of the protection tripping intermediate relay of the low-voltage circuit breaker Q2. Then, the coil of the protection output relay K02 is connected in series, and then the first normally open contact K022 of the protection output relay K02, the first auxiliary normally closed contact Q21 of the low-voltage circuit breaker Q2 and the closing coil HQ2 of the low-voltage circuit breaker Q2 are connected in parallel.

[0011] Furthermore, the contact b of the first group of contacts of the low-voltage bus tie circuit breaker automatic transfer device linkage switch SA is connected in series with the normally closed contact of the low-voltage relay KV1 and the second auxiliary normally closed contact Q12 of the low-voltage circuit breaker Q1, and then connected in parallel with the contact d of the second group of contacts of the low-voltage bus tie circuit breaker automatic transfer device linkage switch SA and the normally closed contact of the low-voltage relay KV2 and the second auxiliary normally closed contact Q22 of the low-voltage circuit breaker Q2, and then connected in series with the normally closed contact of the protection outlet relay K01, the normally closed contact of the protection outlet relay K02, the normally closed contact of the bus tie circuit breaker Q, and the closing coil HQ of the bus tie circuit breaker Q.

[0012] Furthermore, the operating voltage of the DC power supply circuit is 220V.

[0013] Furthermore, the DC power supply positive electrode +KM and the DC power supply negative electrode -KM are configured with a DC circuit breaker.

[0014] Furthermore, the normally open contact TJ1 of the protection tripping intermediate relay of the low-voltage circuit breaker Q1 and the self-holding contact K011, the first normally open contact K012 and the normally closed contact of the protection output relay K01 are all located in the microcomputer protection device of the low-voltage circuit breaker Q1, and the normally open contact TJ2 of the protection tripping intermediate relay of the low-voltage circuit breaker Q2 and the self-holding contact K021, the first normally open contact K022 and the normally closed contact of the protection output relay K02 are all located in the microcomputer protection device of the low-voltage circuit breaker Q2.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are:

[0016] 1. The present invention can automatically switch on the low-voltage bus tie circuit breaker Q when the two high-voltage incoming power sources or the distribution transformer (T1 or T2) lose power, thus ensuring reliable power supply operation;

[0017] 2. When a short circuit fault occurs on the low-voltage busbar W1 (or W2), causing the non-selective quick-break protection of the corresponding distribution transformer high- and low-voltage side circuit breakers to trip, the present invention can achieve automatic circuit locking of the bus tie circuit breaker Q, effectively avoiding the complete power outage of the two bus sections W1 and W2 caused by the accidental closing of the low-voltage side bus tie circuit breaker Q, thereby ensuring safe and reliable power supply.

[0018] 3. The present invention is simple and feasible to implement and does not require additional investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0020] Figure 1 This is a typical primary wiring diagram of a dual power supply and distribution system in the prior art;

[0021] Figure 2 This is a primary wiring diagram of a dual power bus tie circuit breaker automatic power supply and distribution system in the prior art;

[0022] Figure 3 A circuit diagram of a dual power supply automatic switching lockout control circuit provided in an embodiment; DETAILED DESCRIPTION

[0023] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0024] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0025] In a typical dual power supply and distribution system in the prior art, such as Figure 1-2 As shown in the figure, when the 10kV power supply and distribution system is operating normally, the 10kVⅠ incoming line supplies power to the 0.4kV low-voltage bus W1 and its load through the distribution transformer (hereinafter referred to as distribution transformer) T1 and the circuit breaker Q1, and the 10kVⅡ incoming line supplies power to the 0.4kV low-voltage bus W2 and its load through the distribution transformer T2 and the circuit breaker Q2. The 10kVⅠ and Ⅱ section bus tie circuit breaker QF is in hot standby mode, the 0.4kV low-voltage bus W1 and W2 bus tie circuit breaker Q is in hot standby mode, and the other circuit breakers are all closed for operation.

[0026] In order to improve the reliability of the power supply operation of the equipment, a dual power supply backup automatic transfer device is provided. The automatic transfer devices corresponding to the low-voltage circuit breaker Q1, low-voltage circuit breaker Q2 and low-voltage bus tie circuit breaker Q on the low-voltage side of distribution transformer T1 and distribution transformer T2 are installed on the automatic transfer cabinet respectively, and are controlled by a group of contacts of the linkage switch SA1 of the automatic transfer device of T1 low-voltage circuit breaker Q1, a group of contacts of the linkage switch SA2 of the automatic transfer device of T2 low-voltage circuit breaker Q2, and the first group of contacts and the second group of contacts of the linkage switch SA of the automatic transfer device of the low-voltage bus tie circuit breaker Q.

[0027] Under normal power supply operation, the linkage switches SA1, SA2, and SA are set to the "3" position, which means that the circuit breaker is in the "automatic transfer and automatic reset" position. At this time, the contacts a1 and b1 of the linkage switch SA1 of the automatic transfer device of the T1 low-voltage circuit breaker Q1 are connected, the contacts b1 and b2 of the linkage switch SA2 of the automatic transfer device of the T2 low-voltage circuit breaker Q2 are connected, the contacts a and b of the first group of contacts of the linkage switch SA of the automatic transfer device of the low-voltage bus tie circuit breaker Q are connected, and the contacts c and d of the second group of contacts of SA are connected.

[0028] When the 10kVⅠ incoming line and distribution transformer T1 fail and lose power, as long as the two conditions of "distribution transformer low-voltage relay kV loss" and "distribution transformer low-voltage side circuit breaker tripping" are met, the low-voltage bus tie circuit breaker Q standby automatic transfer will be automatically put into operation, and the 10kVⅡ incoming line and distribution transformer T2 will supply all loads of the low-voltage bus W1 through the 0.4kV low-voltage bus tie circuit breaker Q, ensuring safe, continuous and stable power supply for the entire power supply system.

[0029] However, in actual field applications, when a short circuit occurs on low-voltage busbar W1 or busbar W2, due to non-selective protection, both the high- and low-voltage side circuit breakers of distribution transformer T1 or T2 will trip and lose power. At this point, the backup automatic re-opening criteria are met, and the low-voltage bus tie circuit breaker Q will automatically re-open. In this case, power is restored and then lost, causing further repeated damage to the fault point and expanding the scope of the accident. Therefore, a dual-power backup automatic re-opening lockout control circuit can solve this problem.

[0030] Examples, such as Figure 3 As shown, a dual power supply automatic switching lockout control circuit. Figure 1 、 Figure 2During normal power supply operation, all automatic switching devices are enabled, and distribution transformers T1 and T2 operate via 0.4kV low-voltage busbars W1 and W2 via circuit breakers Q1 and Q2, respectively. At this point, the coil of distribution transformer T1's low-voltage relay KV1 is energized, its normally closed contacts open, the auxiliary normally open contacts of distribution transformer T1's low-voltage circuit breaker Q1 close, and the normally closed contacts of low-voltage circuit breaker Q1 open. Similarly, the coil of distribution transformer T2's low-voltage relay KV2 is energized, the normally closed contacts of low-voltage relay KV2 open, the auxiliary normally open contacts of distribution transformer T2's low-voltage circuit breaker Q2 close, and the auxiliary normally closed contacts of low-voltage circuit breaker Q2 open.

[0031] When distribution transformer T1 loses power due to a fault or its power supply line fails, the coil of T1's low-voltage relay KV1 loses power, the normally closed contacts of KV1 return to a closed state, and the coil HQ1 of T1's low-voltage circuit breaker Q1 becomes energized, causing Q1 to trip. Its auxiliary normally closed contacts return to a closed state. Since Q1 trips due to a non-protective action, the coil of the protection output relay K01 within the microcomputer protection device for Q1 will not be energized, and the auxiliary normally closed contacts of K01 will remain closed. Similarly, if distribution transformer T2 loses power due to a fault or its power supply line fails, the coil of the protection output relay K02 within the microcomputer protection device for T2's low-voltage circuit breaker Q2 will not be energized, and the auxiliary normally closed contacts of K02 will also remain closed. At this point, the DC power supply connects to the closing coil HQ of low-voltage bus tie breaker Q. Closing coil HQ is energized, and low-voltage bus tie breaker Q automatically closes and operates busbar W1, ensuring safe and reliable power supply. The backup automatic switching mechanism operates in the same way as above when distribution transformer T2 or its power line fails.

[0032] When a short circuit fault occurs on the low-voltage busbar W1, the high and low voltage circuit breakers Q1 and Q1' of the distribution transformer T1 will cause non-selective quick-break to operate simultaneously, causing the circuit breakers Q1 and Q1' to trip at the same time. T1 loses power, the KV1 coil has no power, the normally closed contact of KV1 is restored to be connected, and the auxiliary normally closed contact Q12 of the circuit breaker Q1 is restored to be closed. However, since the low-voltage circuit breaker Q1 is tripped by protection action, the normally open contact TJ1 of the Q1 protection tripping intermediate relay is closed, connecting the electrical circuit of the protection output relay K01 coil of the low-voltage circuit breaker Q1, and the protection device of the low-voltage circuit breaker Q1 is disconnected. The coil of the protection output relay K01 on the lower part of the transformer is energized and held in place by the manual reset button. The normally closed contact of the protection output relay K01 on the low-voltage circuit breaker Q1 opens, disconnecting the DC power supply control circuit for the coil of the low-voltage bus tie circuit breaker Q. This effectively blocks the automatic re-opening circuit of the low-voltage bus tie circuit breaker Q, effectively preventing the accidental closing and automatic re-opening of the low-voltage bus tie circuit breaker Q. This would cause a complete power outage on both low-voltage bus sections W1 and W2 after distribution transformer T2 supplies power to low-voltage bus W1 via circuit breaker Q2, low-voltage bus W2, and low-voltage bus tie circuit breaker Q. Only after the fault on low-voltage bus W1 is eliminated can the manual reset button S1 be unlocked, de-energizing the coil of the protection output relay K01 on the low-voltage circuit breaker Q1 on distribution transformer T1 and restoring the normally closed contact of the protection output relay K01 on Q1, preparing for the next step of the automatic re-opening operation of the low-voltage bus tie circuit breaker Q. When a short circuit fault occurs on the distribution transformer low-voltage busbar W2, the working principle of the low-voltage bus tie circuit breaker Q standby automatic protection locking circuit is the same as above.

[0033] Therefore, under normal power supply operation, all automatic re-opening devices are enabled. Distribution transformer T1 supplies power to busbar equipment W1 via circuit breaker Q1, and distribution transformer T2 supplies power to busbar equipment W2 via circuit breaker Q2. High-voltage bus tie breaker QF and low-voltage bus tie breaker Q are in hot standby mode. Should a fault occur in either busbar system W1 or W2, even if a non-selective protection trips the high- and low-voltage circuit breakers of distribution transformer T1 or both, the low- and low-voltage circuit breakers of distribution transformer T2, there will be no risk of inadvertent automatic re-opening of low-voltage bus tie breaker Q, potentially impacting the safe power supply of the other system.

[0034] In an abnormal power supply mode, when one distribution transformer is undergoing maintenance while the other operates with two busbar sections, W1 (or W2) and Q, the current quick-break protection of the low-voltage bus tie breaker Q remains enabled, while the high- and low-voltage side current protections of the operating distribution transformer are disabled to prevent the low-voltage busbar fault from escalating into a complete shutdown. During the maintenance period, backup protection can provide protection.

[0035] The contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0036] The above description is merely a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any person skilled in the art may utilize the technical contents disclosed above to change or modify them into equivalent embodiments with equivalent changes for application in other fields. However, any simple modification, equivalent change, and modification of the above embodiments made in accordance with the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A dual power supply automatic switching lockout control circuit, characterized in that: It includes the DC power supply positive electrode +KM, the Q1 protection output tripping circuit, the Q2 protection output tripping circuit, the standby automatic transfer locking control circuit and the DC power supply negative electrode -KM. The DC power supply positive electrode +KM is connected to the Q1 protection output tripping circuit, the Q2 protection output tripping circuit and the standby automatic transfer locking control circuit in parallel and returns to the DC power supply negative electrode -KM to form a loop; The Q1 protection outlet tripping circuit includes a self-holding unlocking switch S1 and a self-holding contact K011 of the protection outlet relay K01, a normally open contact TJ1 of the protection tripping intermediate relay of the low-voltage circuit breaker Q1, and a first normally open contact k012 of the protection outlet relay k01; the Q2 protection outlet tripping circuit includes a self-holding unlocking switch S2 and a self-holding contact K021 of the protection outlet relay K02, a normally open contact TJ2 of the protection tripping intermediate relay of the low-voltage circuit breaker Q2, and a first normally open contact k013 of the protection outlet relay k01. The first normally open contact k022 of the protection outlet relay k02; the standby automatic transfer locking control circuit includes the first group of contacts and the second group of contacts of the low-voltage bus tie circuit breaker automatic transfer device linkage switch SA, the normally closed contacts of the low-voltage relay KV1, the normally closed contacts of the low-voltage relay KV2, the second auxiliary normally closed contact Q12 of the low-voltage circuit breaker Q1, the second auxiliary normally closed contact Q22 of the low-voltage circuit breaker Q2, and the normally closed contacts of the protection outlet relay K01 and the normally closed contacts of the protection outlet relay K02; The Q1 protection outlet tripping circuit also includes a first auxiliary normally closed contact Q11 of the low-voltage circuit breaker Q1 and a closing coil HQ1 of Q1; the Q2 protection outlet tripping circuit also includes a first auxiliary normally closed contact Q21 of the low-voltage circuit breaker Q2 and a closing coil HQ2 of Q2; the standby automatic transfer locking control circuit includes an auxiliary normally closed contact Q of the bus tie circuit breaker Q and a closing coil HQ of Q; the first group of contacts of the low-voltage bus tie circuit breaker automatic transfer device linkage switch SA includes contact a and contact b; the second group of contacts of the low-voltage bus tie circuit breaker automatic transfer device linkage switch SA includes contact c and contact d; The self-holding unlocking switch S1 is connected in series with the self-holding contact K011 of the protection output relay K01 and then connected in parallel with the normally open contact TJ1 of the protection tripping intermediate relay of the low-voltage circuit breaker Q1. Then, the coil of the protection output relay K01 is connected in series, and then the first normally open contact K012 of the protection output relay K01, the first auxiliary normally closed contact Q11 of the low-voltage circuit breaker Q1 and the closing coil HQ1 of the low-voltage circuit breaker Q1 are connected in parallel.

2. A dual power supply automatic switching lockout control circuit according to claim 1, characterized in that: The self-holding unlocking switch S2 is connected in series with the self-holding contact K021 of the protection output relay K02 and then connected in parallel with the normally open contact TJ2 of the protection tripping intermediate relay of the low-voltage circuit breaker Q2. Then, the coil of the protection output relay K02 is connected in series, and then the first normally open contact K022 of the protection output relay K02, the first auxiliary normally closed contact Q21 of the low-voltage circuit breaker Q2 and the closing coil HQ2 of the low-voltage circuit breaker Q2 are connected in parallel.

3. A dual power supply automatic switching lockout control circuit according to claim 1, characterized in that: The contact b of the first group of contacts of the low-voltage bus tie circuit breaker automatic transfer device linkage switch SA is connected in series with the normally closed contact of the low-voltage relay KV1 and the second auxiliary normally closed contact Q12 of the low-voltage circuit breaker Q1, and then connected in parallel with the contact d of the second group of contacts of the low-voltage bus tie circuit breaker automatic transfer device linkage switch SA, the normally closed contact of the low-voltage relay KV2 and the second auxiliary normally closed contact Q22 of the low-voltage circuit breaker Q2, and then connected in series with the normally closed contact of the protection outlet relay K01, the normally closed contact of the protection outlet relay K02, the normally closed contact of the bus tie circuit breaker Q, and the closing coil HQ of the bus tie circuit breaker Q.

4. A dual power supply automatic switching lockout control circuit according to claim 1, characterized in that: The operating voltage of the DC power supply circuit is 220V.

5. A dual power supply automatic switching lockout control circuit according to claim 1, characterized in that: The DC power supply positive electrode +KM and the DC power supply negative electrode -KM are configured with a DC circuit breaker.

6. A dual power supply automatic switching lockout control circuit according to claim 1, characterized in that: The normally open contact TJ1 of the protection tripping intermediate relay of the low-voltage circuit breaker Q1 and the self-holding contact K011, the first normally open contact K012 and the normally closed contact of the protection output relay K01 are all located in the microcomputer protection device of the low-voltage circuit breaker Q1. The normally open contact TJ2 of the protection tripping intermediate relay of the low-voltage circuit breaker Q2 and the self-holding contact K021, the first normally open contact K022 and the normally closed contact of the protection output relay K02 are all located in the microcomputer protection device of the low-voltage circuit breaker Q2.

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