Failure protection circuit for shore equipotential connection

Abstract

The present invention discloses a ship-shore equipotential connection failure protection circuit, comprising an interface relay 1KA, an interface relay 2KA, an interface relay 3KA, an interface relay 4KA, a fuse 1F, a fuse 2F, and more than two transient suppression diodes TVS; the device uses a transient suppression diode TVS for potential monitoring of the ship and the shore, and can meet the requirements of different protection thresholds by selecting different Vrwm values ​​and matching relay coil voltages. In the shore power system, the device can not only protect against the potential difference between the ship and the shore when single-phase grounding occurs and the potential difference exceeds the set threshold, but also can prevent the main circuit breaker from closing or automatically disconnect in the closing position when the equipotential connection is not established or an open circuit occurs after the connection.

Description

Technical Field

[0001] The invention relates to a ship-shore equipotential connection failure protection circuit, belonging to the technical field of ship electrical safety protection equipment. Background Art

[0002] The shipbuilding specifications issued by major classification societies around the world stipulate that the ship's AC three-phase power supply and distribution system can adopt: AC three-wire insulation system (IT system), four-wire system with neutral point grounding and three-wire system using the hull as the neutral line loop (TN system); it also stipulates that when a ship docks at a port to connect to the shore power supply, the ship ground (the ground of the hull) and the shore ground (the grounding device of the shore power supply) should be connected to the same potential.

[0003] If the ship-shore equipotential connection fails, when single-phase grounding occurs in the IT system, or when single-phase grounding occurs in the TN system and the grounding current has not reached the short-circuit protection action value, it will cause the potential between the ship and the shore to be unequal, resulting in contact voltage and step voltage, which will endanger personal safety.

[0004] In the IEC / ISO / IEEE 80005-1:2019 [Utility connections in port–Part 1:High voltage shore connection (HVSC) systems–General requirements] and 80005-3:2016 [Utility connections in port–Part 3:Low Voltage Shore Connection (LVSC) Systems–General requirements] standards, it is repeatedly stated that if the ship-shore equipotential connection fails or the ground fault protection fails, the main circuit breaker should trip and alarm, and the circuit breaker that has not been closed should not be closed. The IEC 80005 standard also stipulates that the ground fault shall not generate a step voltage or contact voltage exceeding 25V at any position in the shore-to-ship power system. (Note: Q / GDW 11468-2016 "Technical Specifications for Port Shore Power Equipment" issued by the State Grid Corporation of China stipulates that "the ground fault shall not generate a step voltage or contact voltage exceeding 0.03kV at any position from the shore to the ship side").

[0005] The Maritime Safety Administration of the People's Republic of China issued a notice on the "Guidelines for the Implementation of Ship Technical Regulations (2021) Inspection Guidelines for Shipboard Shore Power System Shipboard Devices" (hereinafter referred to as the 2021 Guidelines), which further clarified the key points for the inspection of shipboard shore power system shipboard devices. The implementation guidelines require that: an equipotential connection should be established between the ship and the port, and the connection should not change the grounding principle of the ship's power distribution system; the ship should be equipped with facilities for equipotential connection between the hull and the shore (or the grounding device on the pontoon); the "Regulations on the Statutory Inspection of Ships and Offshore Facilities and the Technical Regulations for the Statutory Inspection of Domestic Navigation Ships" (hereinafter referred to as Document No. 1 of 2020) promulgated by the Maritime Safety Administration of the People's Republic of China stipulates that: ① If the equipotential connection is disconnected, the emergency disconnection should be automatically triggered; ② If the equipotential connection is not established, the shore power connection circuit breaker (installed in the shore power connection distribution cabinet) should not be closed or automatically disconnected in the closed position.

[0006] The current equipotential protection technology (for example, the invention patent with patent number 2019201823004: equipotential protection device for ship low-voltage shore power system) can achieve the following when a single-phase grounding fault occurs. If the potential between the ship and the shore is not equal, the main circuit breaker can be tripped and an alarm can be sounded when the potential difference is no more than 25V. However, it cannot achieve the protection in the above two situations: 1. If the equipotential connection is disconnected, the emergency disconnection should be automatically triggered; 2. If the equipotential connection is not established, the shore power connection circuit breaker should not be closed or automatically disconnected in the closed position. Summary of the invention

[0007] The purpose of the present invention is to provide a ship-shore equipotential connection failure protection circuit to solve the technical problem that the prior art cannot automatically trigger the emergency cut-off when the equipotential connection is disconnected, and to solve the technical problem that the shore power connection circuit breaker should not be closed or automatically disconnected in the closed position when the equipotential connection is not established, so as to meet the relevant technical safety requirements in the IEC 80005 standard and the National Maritime Safety Administration 2021 Guidelines and Document No. 1 of 2020.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A ship-shore equipotential connection failure protection circuit comprises an interface relay 1KA, an interface relay 2KA, an interface relay 3KA, an interface relay 4KA, a fuse 1F, a fuse 2F, two or more transient suppression diodes TVS, and a terminal block; one end of the fuse 1F and the fuse 2F are respectively connected to the positive and negative poles of a DC24V power supply, the other end of the fuse 1F is connected in series to the interface relay 1KA break contact, the interface relay 2KA make contact, the interface relay 3KA make contact, and the interface relay 4KA make contact via terminal 1, and then connected to terminal 3; the other end of the fuse 2F is connected in series to the interface relay 2KA coil via terminal 2, and then connected to terminal 5; one end of the interface relay 3KA coil is connected to terminal 1, and the other end of the interface relay 3KA coil is connected to terminal 2; the interface relay 1KA One end of the other pair of break contacts is connected to terminal 1, and the other end is connected to terminal 4. Terminals 2 and 3 are connected to the undervoltage release circuit of the main circuit breaker of the shore power box; Terminals 4 and 5 are connected to the local cut-off button; a pair of make contacts of interface relay 1KA is connected in parallel with a pair of make contacts of interface relay 2KA, one end of the parallel circuit is connected to terminal 6, and the other end of the parallel circuit is connected to one end of the coil of interface relay 1KA. More than two transient suppression diodes TVS are connected in parallel, one end of the parallel circuit is connected to the other end of the coil of interface relay 1KA, and the other end of the parallel circuit is connected to terminal 9. One end of the coil of interface relay 4KA is connected to terminal 6, and the other end of the coil of interface relay 4KA is connected to terminal 10. Terminal 6 is connected to the ship ground PE line, terminal 9 is connected to the shore ground PE line or neutral line N, and terminal 10 is connected to the phase line on the incoming line side of the main circuit breaker of the shore power box.

[0010] The purpose of the present invention can also be further achieved by the following technical measures:

[0011] The aforementioned ship-shore equipotential connection failure protection circuit takes a pair of normally made or normally broken contacts of the interface relay 2KA and connects them to the equipotential alarm circuit.

[0012] The aforementioned ship-shore equipotential connection failure protection circuit takes a pair of normally made or normally broken contacts of the interface relay 3KA and connects them to the DC24V power failure alarm circuit.

[0013] The aforementioned ship-shore equipotential connection failure protection circuit takes a pair of normally made or normally broken contacts of the interface relay 4KA and connects them to the equipotential connection failure alarm circuit.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. This device fully meets the technical requirements of the IEC 80005 standard and the National Maritime Safety Administration's Document No. 1 of 2020 and the 2021 Guidelines: In the shore power system, this device can not only protect against the potential difference (contact voltage and step voltage) between the ship and the shore when single-phase grounding occurs and exceeds the set threshold, but also prevent the main circuit breaker from closing or automatically disconnect in the closed position when the equipotential connection is not established or an open circuit occurs after the connection.

[0016] 2. The potential monitoring devices of the ship and the shore of this device adopt transient suppression diodes (several bidirectional TVS can be connected in parallel for backup). The TVS has a long service life, has a clamping voltage function, and is more reliable than the Zener tube used in the prior art.

[0017] 3. The protection and alarm thresholds of this device can meet different needs: the bidirectional TVS that meets the protection threshold requirements of the present invention has a maximum operating voltage Vrwm with a wide range of optional levels from 6V to ≯25V, and can meet the requirements of different protection thresholds by selecting different Vrwm values ​​and matching relay coil voltages.

[0018] 4. This device is applicable to shore power systems with different electrical systems: The circuit principle of this device is applicable to shore power systems with TN, TT, and IT electrical systems, and there is no need to change the grounding method of the original system.

[0019] 5. This device is suitable for different voltage levels: The circuit principle of this device is suitable for low-voltage (AC230V, 400V, 440V, 690V) shore power systems, and also for high-voltage (AC6KV, 6.6KV, 10KV, 11KV) shore power systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the circuit principle diagram of the automatic trip alarm device for failure of ship-shore equipotential protection;

[0021] Figure 2 This is the external wiring diagram of the terminal block of the embodiment of the automatic trip alarm device for the ship-shore equipotential protection failure;

[0022] Figure 3 This is an application example of the automatic trip alarm device for failure of ship-shore equipotential protection in a three-phase three-wire power system;

[0023] Figure 4 This is a diagram showing an application example of an automatic tripping alarm device for failure of ship-shore equipotential protection in a three-phase four-wire power system. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0025] like Figure 1As shown, a shore equipotential connection failure protection circuit of the present invention comprises an interface relay 1KA, an interface relay 2KA, an interface relay 3KA, an interface relay 4KA, a fuse 1F, a fuse 2F, more than two transient suppression diodes TVS, and a terminal block; one end of the fuse 1F and the fuse 2F are respectively connected to the positive and negative poles of a DC24V power supply, the other end of the fuse 1F is connected in series to the interface relay 1KA break contact, the interface relay 2KA make contact, the interface relay 3KA make contact, and the interface relay 4KA make contact through terminal 1, and then connected to terminal 3; the other end of the fuse 2F is connected in series to the interface relay 2KA coil through terminal 2, and then connected to terminal 5; one end of the interface relay 3KA coil is connected to terminal 1, and the other end of the interface relay 3KA coil is connected to terminal 2; the interface relay One end of the other pair of break contacts of the relay 1KA is connected to terminal 1, and the other end is connected to terminal 4. Terminals 2 and 3 are connected to the undervoltage release circuit of the main circuit breaker of the shore power box; terminals 4 and 5 are connected to the local cut-off button; a pair of make contacts of the interface relay 1KA is connected in parallel with a pair of make contacts of the interface relay 2KA, one end of the parallel circuit is connected to terminal 6, and the other end of the parallel circuit is connected to one end of the coil of the interface relay 1KA. More than two transient suppression diodes TVS are connected in parallel, one end of the parallel circuit is connected to the other end of the coil of the interface relay 1KA, and the other end of the parallel circuit is connected to terminal 9. One end of the coil of the interface relay 4KA is connected to terminal 6, and the other end of the coil of the interface relay 4KA is connected to terminal 10. Terminal 6 is connected to the ship ground PE line, terminal 9 is connected to the shore ground PE line or the neutral line N, and terminal 10 is connected to the phase line on the incoming line side of the main circuit breaker of the shore power box.

[0026] In order to promptly alarm the fault, a pair of make or break contacts of the interface relay 2KA is connected to the equipotential alarm circuit, a pair of make or break contacts of the interface relay 3KA is connected to the DC24V power failure alarm circuit, and a pair of make or break contacts of the interface relay 4KA is connected to the equipotential connection failure alarm circuit. The alarm circuit can use an indicator light or an alarm bell as an alarm means, and the above contacts start its alarm work. The components used in this embodiment are shown in the following Tables 1 and 2:

[0027] Table 1:

[0028]

[0029] Table 2:

[0030]

[0031] The main features and functions of the present invention are as follows:

[0032] (1) When the potential difference between the ship hull (ship ground) and the ground wire (shore ground) of the port power system reaches the set threshold, the main circuit breaker of the shipboard shore power box will automatically trip and alarm if it is closed, and it will not be closed if it is not closed;

[0033] (2) When the equipotential connection between the ship and the shore has not been established, the main circuit breaker of the ship's shore power box cannot be closed;

[0034] (3) When the main circuit breaker of the shipboard shore power box is closed, if the equipotential connection established between the ship and the shore fails (the conductor connecting the ship and the shore is open due to any reason), the main circuit breaker will automatically trip and alarm;

[0035] (4) This device can be applied to TN, TT, and IT power systems, and there is no need to change the grounding principle of the ship's power distribution system;

[0036] (5) In addition to the ship's shore power system, the protection scope of this device can also be applied to shore buildings or equipment. When the equipotential connection and ground fault protection fail, causing the potential difference between the ship and the shore to exceed the set threshold, the main circuit breaker can be automatically cut off and an alarm can be issued, thereby effectively avoiding the harm to human body and equipment safety caused by contact voltage and step voltage generated by single-phase grounding.

[0037] The working principle of the present invention is as follows:

[0038] 1. The auxiliary power supply of this device is DC24V, which can be the DC24V power supply of the ship's charging and discharging board, or a switching power supply with an output of DC24V (capacity of about 50VA).

[0039] 2. The DC24V auxiliary power supply is connected to the terminal block with fuse (hereinafter referred to as terminal block, such as Figure 2 As shown in the figure, the incoming line terminals + and - of fuses 1F and 2F (whose terminal numbers are: +, -, 1F, 2F, 1-10, 21-23, 31-33, 41-43) are protected by fuses 1F and 2F for short circuit. The outgoing line sides of 1F and 2F are connected to terminals 1 and 2 of the terminal block respectively. Under normal working conditions, the local cut-off button is not pressed, the interface relay 2KA is energized and closed, its make contact is connected, and its break contact is disconnected.

[0040] 3. Interface relay 3KA is connected between terminal 1 and terminal 2 of the terminal block to monitor the auxiliary power supply. When the auxiliary power supply DC24V is normal, 3KA is energized, its make contact is connected, and its break contact is disconnected; when the auxiliary power supply DC24V is abnormal, 3KA is reset, its make contact is disconnected, and the power supply of the undervoltage release of the main circuit breaker is cut off. Terminals 31, 32, and 33 of the terminal block provide 3KA's DC24V power failure alarm contacts.

[0041] 4. Terminals 2 and 3 of the terminal block provide DC24V working power to the undervoltage release circuit of the main circuit breaker, so that the main circuit breaker is ready for closing.

[0042] 5. Terminals 4 and 5 of the terminal block are connected to a self-locking button for on-site cutting. When the button is pressed, 2KA loses power and resets. Its moving contact is disconnected, cutting off the power supply of the undervoltage release of the main circuit breaker. According to the provisions of IEC 80005-3, the self-locking button must be reset manually before the main circuit breaker can be closed again.

[0043] 6. Terminal 6 of the terminal block is connected to the ship ground PE, and terminal 10 is connected to any phase line on the power supply incoming line side of the main circuit breaker. When the equipotential connection between the ship ground and the shore is effective, 4KA is energized, its make contact is connected, and the break contact is disconnected; when the equipotential connection between the ship ground and the shore has not been established or fails after establishment (the shore ground E line or the shore power neutral line N is not connected to the ship ground PE, or an open circuit occurs for some reason after connection), the interface relay 4KA is reset, its make contact is disconnected, and the power supply of the main circuit breaker undervoltage release is cut off. Terminals 41, 42, and 43 of the terminal block provide 4KA equipotential connection failure alarm contacts.

[0044] 7. Use two transient suppression diodes (bidirectional TVS) (TVS1 and TVS2 are standby for each other) or multiple TVS in parallel with interface relays 1KA and 2KA to form an equipotential monitoring device for ship and shore. After calculation and experiment, the maximum working voltage Vrwm of TVS should be selected between 13-16V, the clamping voltage Vc should be no more than 24.5V, and the peak pulse current Ipp of TVS is not required. 1KA is a miniature interface intermediate relay, and the rated voltage of the coil is AC12V. Three TVS with Vrwm values ​​between 13-16V are used in the experiment. After multiple tests, the sampling voltage generated by the ship-shore potential difference is added between terminal 6 and terminal 9 of the terminal block. When the sampling voltage is 20.5V, 22V, and 23V respectively, 1KA is energized and self-protected, its make contact is connected and the break contact is disconnected, 2KA is reset, its make contact is disconnected, and the power supply of the undervoltage release of the main circuit breaker is cut off. Terminals 21, 22, and 23 of the terminal block provide 2KA equipotential alarm contacts; when the sampling voltage of terminals 6 and 9 is reduced by 50%, 1KA is reset and 2KA is energized; the required protection threshold can be obtained by selecting the Vrwm value and Vc value of TVS.

[0045] 8. If any one or several of the above protection links are activated, the undervoltage release circuit of the main circuit breaker of the shore power box will lose power, the closed circuit breaker will automatically trip, and the unclosed circuit breaker will be unable to close.

[0046] 9. This device can be used in emergency: just short-circuit terminal 1 and terminal 3 of the terminal block of this device, and the shore power system can be temporarily closed for use.

[0047] like Figure 3, Figure 4 As shown, it is a circuit diagram of an application embodiment of the automatic tripping alarm device for failure of ship-shore equipotential protection in a three-phase three-wire power system and a three-phase four-wire power system.

[0048] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A shore equipotential connection failure protection circuit, characterized in that , including interface relay 1KA, interface relay 2KA, interface relay 3KA, interface relay 4KA, fuse 1F, fuse 2F, more than two transient suppression diodes TVS, and terminal block; one end of the fuse 1F and fuse 2F are respectively connected to the positive and negative poles of the DC24V power supply, the other end of the fuse 1F is connected in series to the interface relay 1KA break contact, the interface relay 2KA make contact, the interface relay 3KA make contact, and the interface relay 4KA make contact through terminal 1 and then connected to terminal 3, the other end of the fuse 2F is connected in series to the coil of the interface relay 2KA through terminal 2 and then connected to terminal 5, one end of the interface relay 3KA coil is connected to terminal 1, the other end of the interface relay 3KA coil is connected to terminal 2, one end of the other pair of break contacts of the interface relay 1KA is connected to terminal 1, and the other end is connected to terminal 4, terminals 2 and 3 are connected to the shore power The undervoltage release circuit of the main circuit breaker of the box; Terminals 4 and 5 are connected to the local cut-off button; a pair of make contacts of interface relay 1KA are connected in parallel with a pair of make contacts of interface relay 2KA, one end of the parallel circuit is connected to terminal 6, and the other end of the parallel circuit is connected to one end of the coil of interface relay 1KA, more than two transient suppression diodes TVS are connected in parallel, one end of the parallel circuit is connected to the other end of the coil of interface relay 1KA, and the other end of the parallel circuit is connected to terminal 9, one end of the coil of interface relay 4KA is connected to terminal 6, and the other end of the coil of interface relay 4KA is connected to terminal 10, terminal 6 is connected to the ship ground PE line, terminal 9 is connected to the shore ground PE line or neutral line N, and terminal 10 is connected to the phase line on the incoming line side of the main circuit breaker of the shore power box; a pair of make or break contacts of interface relay 2KA are connected to the equipotential alarm circuit; a pair of make or break contacts of interface relay 3KA are connected to the DC24V power failure alarm circuit.

2. The shore equipotential connection failure protection circuit according to claim 1, characterized in that: Take a pair of normally made or normally broken contacts of the interface relay 4KA and connect them to the equipotential connection failure alarm circuit.

Images