N-phase ground relay state detection circuit
By sampling the voltage across the relay using a series power circuit and a sampling circuit, the accuracy and cost issues of N-phase-to-ground relay status detection in existing technologies are resolved, achieving fast and accurate relay status detection and ensuring stable system operation.
Patent Information
- Application Number
- CN202423047229.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-10
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-12-10
AI Technical Summary
Existing N-phase ground relay status detection circuits cannot accurately determine the status of the relay, and the detection circuits are complex and costly.
A series power circuit and sampling circuit are used to sample the voltage across the first and second relays under test. The state of the relays is detected in both grid-connected and off-grid modes, and the state is determined using a capacitor and a voltage sampler.
It enables rapid and accurate detection of relay status, ensuring stable operation of the system in both grid-connected and off-grid modes, while reducing the complexity and cost of the detection circuit.
Smart Images
Figure CN223624377U_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of relay status detection circuit technology, and in particular relates to an N-phase-to-ground relay status detection circuit. Background Technology
[0002] Since it is a TN system when connected to the grid, the N-phase ground relay is required to be disconnected. When disconnected from the grid, it is an IT system, which requires the N-phase ground relay to be closed. In order to meet safety requirements, the N-phase ground needs to be isolated by two relays in series. There are two ways the relay can be damaged: sticking (i.e., unable to disconnect) and unable to close. Therefore, it is essential to check whether the relay is in the correct state.
[0003] Existing detection circuits have the following drawbacks:
[0004] 1. The N-phase ground relay cannot know its status (whether it is in the on or off state) or whether it can switch states correctly.
[0005] 2. Relay status detection usually requires complex circuits, which is too costly. Utility Model Content
[0006] In view of this, the main objective of this application is to provide an N-phase-to-ground relay state detection circuit.
[0007] The technical solution adopted in this application is as follows: an N-phase ground relay state detection circuit, comprising:
[0008] A power circuit, the power circuit including a first relay under test RLY1, a second relay under test RLY2, a first capacitor C1 and a second capacitor C2;
[0009] The first relay under test RLY1 and the second relay under test RLY2 are connected in series on the N line, and the output terminal of the second relay under test RLY2 is grounded;
[0010] The first capacitor C1 and the second capacitor C2 are connected in series on the C-phase line. The first capacitor C1 is connected in parallel with the first relay under test RLY1. The second capacitor C2 is connected in parallel with the second relay under test RLY2, and the output terminal of the second capacitor C2 is grounded.
[0011] The sampling circuit samples the voltages across the first relay under test RLY1 and the second relay under test RLY2, respectively.
[0012] Furthermore, the sampling circuit includes a voltage sampler V1 and a voltage sampler V2; the voltage sampler V1 is connected in parallel with the second capacitor C2; the voltage sampler V2 is connected in parallel with the first capacitor C1 and the second capacitor C2.
[0013] Furthermore, in grid-connected mode, the power circuit includes an equivalent resistance R, which is connected in parallel with the first relay under test RLY1 and the second relay under test RLY2.
[0014] Compared with the prior art, the present application has the following advantages: when switching between grid-connected and off-grid modes, by connecting a sampling circuit to both ends of the two relays under test, the sampling circuit samples the voltage at both ends of the two relays under test respectively, which can quickly complete the detection of different states of the relays during grid-connected and off-grid modes, ensuring the stable and reliable operation of the system. Attached Figure Description
[0015] The following figures are for illustrative purposes only and are not intended to limit the scope of this application, wherein:
[0016] Figure 1 This application provides an N-phase-to-ground relay detection circuit when the device is offline.
[0017] Figure 2 This application provides an N-phase ground relay detection circuit for when the circuit is connected to the grid. Detailed Implementation
[0018] To make the objectives, technical solutions, design methods, and advantages of this application clearer, the following detailed description, in conjunction with the accompanying drawings, provides specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application.
[0019] As one embodiment of this application, refer to Figure 1 This application provides an N-phase ground relay state detection circuit, including a power circuit and a sampling circuit.
[0020] The power circuit includes a first relay under test (RLY1), a second relay under test (RLY2), a first capacitor (C1), and a second capacitor (C2). The first relay under test (RLY1) and the second relay under test (RLY2) are connected in series on the neutral (N) line, and the output terminal of the second relay under test (RLY2) is grounded. The first capacitor (C1) and the second capacitor (C2) are connected in series on the collector (C) line, and the first capacitor (C1) is connected in parallel with the first relay under test (RLY1). The second capacitor (C2) is connected in parallel with the second relay under test (RLY2), and the output terminal of the second capacitor (C2) is grounded.
[0021] The sampling circuit includes a voltage sampler V1 and a voltage sampler V2; the voltage sampler V1 is connected in parallel with the second capacitor C2; the voltage sampler V2 is connected in parallel with the first capacitor C1 and the second capacitor C2; the sampling circuit samples the voltages across the first relay under test RLY1 and the second relay under test RLY2 respectively.
[0022] When disconnecting from the grid, disconnect the relay on the grid-connected side, and do not ground the neutral (N) line. Only check if it cannot be energized. The detection phenomenon is as follows:
[0023] 1. V1=0, V2=0, the relays are working normally, that is, both relays are engaged;
[0024] 2. V1=V2=1 / 2Vcn, relay 2 cannot be activated;
[0025] 3. V1=0, V2 is floating and ≠0, relay 1 cannot be activated;
[0026] 4. V1 = 1 / 2Vcn, V2 is floating and ≠ 0, so relays 1 and 2 cannot be activated;
[0027] In the off-grid state, the relay malfunctions when V2≠0; and it functions normally when V2=0.
[0028] As one embodiment of this application, refer to Figure 2 This application provides an N-phase ground relay state detection circuit, including a power circuit and a sampling circuit.
[0029] The power circuit includes a first relay under test (RLY1), a second relay under test (RLY2), a first capacitor (C1), a second capacitor (C2), and an equivalent resistance (R). The first relay under test (RLY1) and the second relay under test (RLY2) are connected in series on the neutral (N) line, and the output terminal of the second relay under test (RLY2) is grounded. The first capacitor (C1) and the second capacitor (C2) are connected in series on the collector (C) line, and the first capacitor (C1) is connected in parallel with the first relay under test (RLY1). The second capacitor (C2) is connected in parallel with the second relay under test (RLY2), and its output terminal is grounded. The equivalent resistance (R) is connected in parallel with both the first relay under test (RLY1) and the second relay under test (RLY2).
[0030] The sampling circuit includes a voltage sampler V1 and a voltage sampler V2; the voltage sampler V1 is connected in parallel with the second capacitor C2; the voltage sampler V2 is connected in parallel with the first capacitor C1 and the second capacitor C2; the sampling circuit samples the voltages across the first relay under test RLY1 and the second relay under test RLY2 respectively.
[0031] During grid connection, the grid-side relay is activated, and the far end of the neutral (N) line is grounded. Only the presence of adhesion is checked, and the following phenomena are observed:
[0032] 1. V1=1 / 2Vcn, V2=0, the relays are working normally, that is, both relays are disconnected;
[0033] 2. V1=0, V2=0, either relay 1 or 2 is stuck together, or both relay 1 and 2 are stuck together.
[0034] Under grid-connected conditions, the relay malfunctions when V1=0; it functions normally when V1=1 / 2Vcn (i.e., when the voltage at the second relay under test RLY2 is equal to half the voltage difference between the N-phase line voltage and the C-phase line voltage).
[0035] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or technological improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.
Claims
1. A state detection circuit for an N-phase ground relay, characterized in that, include: A power circuit, the power circuit including a first relay under test RLY1, a second relay under test RLY2, a first capacitor C1 and a second capacitor C2; The first relay under test RLY1 and the second relay under test RLY2 are connected in series on the N line, and the output terminal of the second relay under test RLY2 is grounded; The first capacitor C1 and the second capacitor C2 are connected in series on the C-phase line. The first capacitor C1 is connected in parallel with the first relay under test RLY1. The second capacitor C2 is connected in parallel with the second relay under test RLY2, and the output terminal of the second capacitor C2 is grounded. The sampling circuit samples the voltages across the first relay under test RLY1 and the second relay under test RLY2, respectively.
2. The N-phase-to-ground relay state detection circuit according to claim 1, characterized in that, The sampling circuit includes a voltage sampler V1 and a voltage sampler V2; the voltage sampler V1 is connected in parallel with the second capacitor C2; the voltage sampler V2 is connected in parallel with the first capacitor C1 and the second capacitor C2.
3. The N-phase-to-ground relay state detection circuit according to claim 1, characterized in that, In grid-connected mode, the power circuit includes an equivalent resistance R, which is connected in parallel with the first relay under test RLY1 and the second relay under test RLY2.