DC grounding detection indication system

Abstract

The utility model discloses a direct current grounding detection indication system which comprises a control power supply, an amplification circuit with a lamp and a leakage current sensor, and the control power supply simultaneously supplies power to the amplification circuit with the lamp and the leakage current sensor. The amplification circuit with the lamp is connected with the leakage current sensor, amplifies an output voltage signal of the leakage current sensor, and then drives an internal indication lamp to emit light for grounding indication. According to the utility model, the output voltage signal of the leakage current sensor is amplified through the amplification circuit with the lamp, and then the positive and negative indication lamps inside the amplification circuit with the lamp are driven to emit light for positive and negative grounding indication, so that whether a current loop has a grounding condition can be visually observed, especially in a multi-branch DC output loop in a DC power distribution system; the grounding state of a branch loop can be visually displayed, and whether the anode of the loop is grounded or not is displayed; the device is simple and reliable, is low in cost, is small in significance of fixed value display of the grounding resistance, can qualitatively judge the grounding, and can finish the qualitative judgment of the grounding.

Description

Technical Field

[0001] The utility model relates to a DC grounding detection and indication system. Background Art

[0002] With the maturity and economic improvement of power electronics technology, and the introduction of DC terminal electrical equipment, DC distribution networks have gradually emerged in recent years. The DC system has characteristics such as no harmonics and high safety, making it prominent in low-voltage DC distribution networks.

[0003] The low-voltage DC distribution system is different from the low-voltage AC system. There is usually no grounding point on the DC power supply side similar to that of the AC power supply. Therefore, a DC single-pole grounding cannot form a loop. After an AC phase wire is grounded, the current can be collected through the ground to the grounding point of the transformer to form a current loop. Therefore, the AC system can display the grounding current. Since there is no grounding point on the power supply side of the DC system, when a certain pole in the DC system is grounded, due to the potential difference, the migration of electrons will form a current, which is called leakage current.

[0004] Usually, bus insulation monitoring and branch insulation monitoring are used to detect the grounding protection of the DC system. The insulation conditions of the system are comprehensively judged by the two, and the grounding branch or grounding resistance can be detected qualitatively and quantitatively.

[0005] At present, the DC distribution grounding detection sensor is usually a leakage current sensor. The primary side of the DC distribution loop passes through the sensor iron core. The sensor monitors the leakage current value caused by the grounding of a certain pole. Usually, the leakage current signal of 0 to ±20 mA is converted into a voltage signal of 0 to ±5 V; using the leakage current signal sampled by the leakage current sensor and combining the grounding resistance value obtained by the bus insulation detection device, the grounding fault (positive grounding, negative grounding or others) of the DC distribution loop is comprehensively judged.

[0006] The DC grounding detection and indication system is mainly used to qualitatively judge whether there is grounding in this branch, and whether it is positive grounding or negative grounding. As Figure 1 shown, the conventional DC grounding detection and indication system includes a control power supply 9, a leakage current sensor 10, a microcomputer system 11 for collecting and processing signals, and a display device 12. The control power supply, the microcomputer system and the display device are connected in sequence, and the leakage current sensor is respectively connected to the control power supply and the microcomputer system. The DC grounding detection and indication system has the following defects: (1) The signals detected by the leakage current sensor need to be collected, processed and analyzed, and then the grounding situation can be displayed through the display device; (2) The whole system is a microcomputer-based system, which requires programming, signal collection and display, etc., and the system is complex. Summary of the Utility Model

[0007] The utility model aims to provide a DC grounding detection and indication system, which can detect and indicate the grounding of a DC circuit without complicated control and detection systems, and can distinguish grounding electrodes.

[0008] The purpose of the utility model is achieved through the following technical solutions: a DC grounding detection and indication system, characterized in that it includes a control power supply, a lighted amplifier circuit and a leakage current sensor, the control power supply simultaneously powers the lighted amplifier circuit and the leakage current sensor, the lighted amplifier circuit is connected to the leakage current sensor and amplifies the output voltage signal of the leakage current sensor to drive its own internal indicator light to emit light for grounding indication.

[0009] The utility model amplifies the output voltage signal of the leakage current sensor through the lighted amplifier circuit, and then drives the positive and negative pole indicator lights inside the lighted amplifier circuit to light up to indicate the positive and negative pole grounding, so that it can be intuitively seen whether there is a grounding situation in the current circuit, especially in a multi-branch DC output circuit in a DC power distribution system, it can intuitively display the grounding status of the branch circuit, and display whether the positive pole or the negative pole of the circuit is grounded, without the need for a complex microcomputer system to perform detection and sampling and other processing to display the grounding and the grounding electrode. Moreover, the utility model is simple, reliable and low in cost, and the fixed value display of the grounding resistance is of little significance, and a qualitative judgment of the grounding is sufficient. The utility model can complete the qualitative judgment of the grounding.

[0010] The lamp amplifier circuit of the utility model is composed of an amplifier circuit, a resistor R1, a resistor R2, a voltage-dividing resistor R, a light-emitting diode LED1 and a light-emitting diode LED2. The amplifier circuit has eight pins, the first to third pins have no external connection, the eighth pin is connected to the positive electrode of the control power supply, the positive electrode of the control power supply is connected in parallel to the positive end of the leakage current sensor, the fourth pin is connected to the negative electrode of the control power supply, and the negative electrode of the control power supply is connected in parallel to the negative end of the leakage current sensor, the seventh pin is connected to any end of the resistor R1 and any end of the voltage-dividing resistor R, the other end of the voltage-dividing resistor R is connected in parallel to the positive end of the light-emitting diode LED1 and the negative end of the light-emitting diode LED2, the sixth pin is connected in parallel to the other end of the resistor R1, and the node after parallel connection is then connected in series to any end of the resistor R2, the terminal number M of the leakage current sensor is connected to the fifth pin of the amplifier circuit, the terminal number G of the leakage current sensor is connected to the ground end of the control power supply, and the terminal number G of the leakage current sensor is connected in parallel to the other end of the resistor R2, the negative end of the light-emitting diode LED1 and the positive end of the light-emitting diode LED2.

[0011] The lamp-equipped amplifier circuit of the utility model is integrated on a circuit board in the leakage current sensor to form a leakage current sensor with a leakage indicator light, which can simplify the circuit complexity and wiring.

[0012] The resistor R1 and / or resistor R2 in the present utility model is an adjustable resistor, which can adjust the sensitivity of the leakage current indication of the loop.

[0013] Compared with the prior art, the present utility model has the following remarkable effects:

[0014] ⑴ The present utility model amplifies the output voltage signal of the leakage current sensor through a lamp-amplifying circuit and then drives the positive and negative indicator lamps inside the lamp-amplifying circuit to emit light for positive and negative ground indication, so that it can be directly seen whether there is a grounding situation in the current loop. Especially in the multi-branch DC output loop of the DC power distribution system, it can directly display the grounding state of the branch loop, indicating whether the positive or negative pole of the loop is grounded, without the need for a complex microcomputer system to perform detections, samplings and other processes to display the grounding and the grounding pole.

[0015] ⑵ The present utility model is simple, reliable and low-cost, and can complete qualitative determination of grounding. Description of the Drawings

[0016] The following further describes the present utility model in detail with reference to the drawings and specific embodiments.

[0017] Figure 1 is a schematic diagram of the composition structure of a conventional DC grounding detection and indication system;

[0018] Figure 2 is a schematic diagram of the composition structure of the present utility model;

[0019] Figure 3 is a schematic diagram of the composition structure of the lamp-amplifying circuit of the present utility model;

[0020] Figure 4 is a schematic diagram of the connection of the lamp-amplifying circuit of the present utility model with the control power supply and the leakage current sensor. Detailed Embodiments

[0021] As Figures 2 to 4 shown, a DC grounding detection and indication system of the present utility model includes a control power supply 9, a lamp-amplifying circuit 13 and a leakage current sensor 10. The control power supply supplies power to both the lamp-amplifying circuit and the leakage current sensor at the same time. The lamp-amplifying circuit is connected to the leakage current sensor to amplify the output voltage signal of the leakage current sensor and then drive the indicator lamp inside itself to emit light for ground indication.

[0022] See Figure 2, L+, L- are the output DC buses, and 1QL, 2QL are the DC distribution feed-out branches; the DC feed-out buses of the first circuit under test 14 and the second circuit under test 15 pass through the iron core of the leakage current sensor 10, and the control power supply provides ±12V power for the leakage current sensor. The control power supply also provides power for the circuit with a light-emitting amplifier, providing power for the chip inside the circuit with a light-emitting amplifier; the circuit with a light-emitting amplifier amplifies the output voltage signal of the leakage current sensor and then drives the LED lamp beads to emit light.

[0023] See Figure 3 、 Figure 4 , the circuit with a light-emitting amplifier 13 consists of an amplifier circuit, resistor R1, resistor R2, voltage-dividing resistor R, light-emitting diode LED1, and light-emitting diode LED2. The amplifier circuit has eight pins. Among them, the first pin 1, the second pin 2, and the third pin 3 have no external connections. The eighth pin 8 is connected to the positive pole (+12V) of the control power supply, and the positive pole of the control power supply is connected in parallel to the positive terminal of the leakage current sensor. The fourth pin 4 is connected to the negative pole (-12V) of the control power supply, and the negative pole of the control power supply is connected in parallel to the negative terminal of the leakage current sensor. The seventh pin 7 is connected to either end of resistor R1 and either end of voltage-dividing resistor R. The other end of voltage-dividing resistor R is connected in parallel to the positive terminal of light-emitting diode LED1 and the negative terminal of light-emitting diode LED2. The sixth pin 6 is connected in parallel to the other end of resistor R1, and the node after parallel connection is then connected in series to either end of resistor R2. The terminal number M of the leakage current sensor is connected to the fifth pin 5 of the amplifier circuit, and the terminal number G of the leakage current sensor is connected to the grounding terminal (GND) of the control power supply, and the terminal number G of the leakage current sensor is connected in parallel to the other end of resistor R2, the negative terminal of light-emitting diode LED1, and the positive terminal of light-emitting diode LED2. The connections of resistor R1, resistor R2, and voltage-dividing resistor R to the pins are not positive or negative; for light-emitting diodes LED1 and LED2, all connection pins need to be positive or negative.

[0024] In other embodiments, the circuit with a light-emitting amplifier is integrated on the circuit board inside the leakage current sensor to form a leakage current sensor with a leakage indicator light, which can simplify the loop complexity and wiring.

[0025] The working principle of the present utility model is:

[0026] 1. The Hall leakage current sensor linearly converts the corresponding leakage current signal of 0 to ±20 mA into a voltage signal of 0 to ±5V and outputs it.

[0027] 2. When a certain extremely high-resistance grounding occurs in the feed-out loop, in the low-voltage DC distribution system, the leakage current values are all relatively small, usually in the mA level. Assuming the leakage current value may only be 1 mA, the sensor correspondingly outputs a voltage of 250 mV. If the other pole is grounded equally, it will be displayed as a negative value, and the output will also be negative.

[0028] 3. When the voltage is 250 mV and the current is extremely small and cannot drive the LED indicator, an amplifier circuit is required to control the output voltage and current, and at the same time limit the voltage and current to prevent damage to the LED indicator.

[0029] 4. In the amplifier circuit with a lamp, R1 and R2 are used to adjust the amplification factor; LM358 is a typical packaged amplifier circuit, and its output characteristics are that the voltage is about 1.5 V lower than the power supply, and the maximum current is 20 mA, which will not exceed the allowable current of the LED lamp bead; the resistor R is used for voltage division to protect the LED lamp bead from overvoltage; LED1 and LED2 are the positive-grounding indicator and negative-grounding indicator respectively.

[0030] 5. Before the system is finalized, the specification parameters of the LED lamp bead are as follows: the minimum driving voltage is 1.6 V; for the output feeder circuit of DC 220 V, the leakage current value of the single-pole grounding resistance of 40 KΩ is 2 mA (sensor output voltage 250 mV). In this state, if it is necessary to indicate that the LED is grounded, adjust the values of R1 and R2 so that the amplification ratio of the amplification circuit is 1.6 V / 250 mV = 6.4 times. At this time, send the 250 mV signal output by the sensor to the amplifier circuit, and the amplifier circuit outputs 1.6 V, just lighting up the LED lamp bead. If you want the leakage current to be 1 mA to indicate leakage (the indicator light is on), then adjust the amplification ratio to 12.8 times accordingly, and so on.

[0031] 6. In actual use, R1 or R2 can be set as adjustable resistors or both can be adjustable to adjust the sensitivity of the leakage current indication of the circuit.

[0032] 7. LED1 and LED2 are light-emitting diode lamp beads, and they are connected in reverse and are respectively used for positive-grounding and negative-grounding indication.

[0033] The implementation manners of the present utility model are not limited thereto. Based on the above content of the present utility model, according to the common technical knowledge and customary means in the art, without departing from the above basic technical idea of the present utility model, the present utility model can also be modified, replaced or changed in many other forms, all of which fall within the scope of the protection of the rights of the present utility model.

Claims

1. A DC grounding detection and indication system, characterized in that: It includes a control power supply, a lighted amplifier circuit and a leakage current sensor. The control power supply supplies power to the lighted amplifier circuit and the leakage current sensor at the same time. The lighted amplifier circuit is connected to the leakage current sensor to amplify the output voltage signal of the leakage current sensor and then drive its internal indicator light to light up for grounding indication.

2. The DC grounding detection and indication system according to claim 1, characterized in that: The lighted amplifier circuit is composed of an amplifier circuit, a resistor R1, a resistor R2, a voltage-dividing resistor R, a light-emitting diode LED1 and a light-emitting diode LED2. The amplifier circuit has eight pins, the first to third pins have no external connection, the eighth pin is connected to the positive electrode of the control power supply, the positive electrode of the control power supply is connected in parallel to the positive end of the leakage current sensor, the fourth pin is connected to the negative electrode of the control power supply, and the negative electrode of the control power supply is connected in parallel to the negative end of the leakage current sensor, the seventh pin is connected to any end of the resistor R1 and any end of the voltage-dividing resistor R, the other end of the voltage-dividing resistor R is connected in parallel to the positive end of the light-emitting diode LED1 and the negative end of the light-emitting diode LED2, the sixth pin is connected in parallel to the other end of the resistor R1, and the parallel node is then connected in series to any end of the resistor R2, the terminal number M of the leakage current sensor is connected to the fifth pin of the amplifier circuit, the terminal number G of the leakage current sensor is connected to the ground end of the control power supply, and the terminal number G of the leakage current sensor is connected in parallel to the other end of the resistor R2, the negative end of the light-emitting diode LED1 and the positive end of the light-emitting diode LED2.

3. The DC grounding detection and indication system according to claim 2, characterized in that: The resistor R1 and / or the resistor R2 are adjustable resistors.

4. The DC grounding detection and indication system according to any one of claims 1 to 3, characterized in that: The lighted amplifier circuit is integrated on a circuit board in the leakage current sensor to form a leakage current sensor with a leakage indicator light.

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