CN204740058U - An electromagnetic flowmeter self-test circuit for the insulation resistance of the excitation coil - Google Patents
An electromagnetic flowmeter self-test circuit for the insulation resistance of the excitation coil Download PDFInfo
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Abstract
本实用新型涉及一种励磁线圈的绝缘电阻测试电路，其特征在于：包括第一电阻、第二电阻、第一运算放大器、第二运算放大器、第三电阻和第四电阻，其中第一运算放大器、第二运算放大器的放大倍数均为1，且第一运算放大器为高输入阻抗运算放大器，第一电阻的第一端与恒流源相连，第一电阻的第二端连接励磁线圈的绝缘电阻后接地，同时第一电阻的第二端连接第二电阻后与第一运算放大器的同相输入端连接，第一运算放大器的反相输入端与输出端连接，第一运算放大器的输出端分别连接第三电阻和第四电阻后接地，第四电阻的第一端与第二运算放大器的同相输入端连接，第二运算放大器的反相输入端与输出端连接，并与电磁流量计内部的A/D转换电路输入端连接。
The utility model relates to an insulation resistance testing circuit of an excitation coil, which is characterized in that it comprises a first resistor, a second resistor, a first operational amplifier, a second operational amplifier, a third resistor and a fourth resistor, wherein the first operational amplifier , The magnification of the second operational amplifier is 1, and the first operational amplifier is a high input impedance operational amplifier, the first end of the first resistor is connected to the constant current source, and the second end of the first resistor is connected to the insulation resistance of the excitation coil After grounding, at the same time the second end of the first resistor is connected to the second resistor and then connected to the non-inverting input end of the first operational amplifier, the inverting input end of the first operational amplifier is connected to the output end, and the output ends of the first operational amplifier are respectively connected to The third resistor and the fourth resistor are connected to the ground, the first end of the fourth resistor is connected to the non-inverting input end of the second operational amplifier, the inverting input end of the second operational amplifier is connected to the output end, and is connected to A inside the electromagnetic flowmeter. /D conversion circuit input connection.
Description
技术领域 technical field
本实用新型涉及一种电磁流量计自行对励磁线圈的绝缘电阻测试电路。 The utility model relates to a circuit for testing the insulation resistance of an excitation coil by an electromagnetic flowmeter itself.
背景技术 Background technique
电磁流量计的励磁回路包括：恒流源S，四个电子元件组成的开关和励磁线圈L，参见附图1所示。若需要励磁磁场，一个方法是恒流源提供励磁电流，电磁流量计控制板控制电子开关K1、K4导通，则励磁电流从恒流源经过电子开关K1，由A点流经励磁线圈B点，至电子开关K4组成回路。如果需要产生相反的励磁磁场，则电磁流量计控制板控制电子开关K2、K3导通，励磁电流从恒流源S经过电子开关K3，由B点流经励磁线圈A点，至电子开关K2组成回路。如果电磁流量计控制板使四个电子开关都不导通，则励磁线圈没有励磁电流通过，电磁流量计就不会产生励磁磁场。上述为电磁流量计的励磁原理。绝缘良好的励磁线圈可以使电磁流量计的励磁电流稳定，可靠，无任何分流，从而保持磁场强度的精确和稳定，因此对励磁线圈的绝缘电阻进行测试是有很大意义的，然而现有技术中没有提供一种较为方便实用的励磁线圈的绝缘电阻测试电路。 The excitation circuit of the electromagnetic flowmeter includes: a constant current source S, a switch composed of four electronic components and an excitation coil L, as shown in Figure 1. If the excitation magnetic field is required, one method is that the constant current source provides the excitation current, and the electromagnetic flowmeter control board controls the electronic switches K1 and K4 to conduct, then the excitation current passes through the electronic switch K1 from the constant current source, and flows from point A to point B of the excitation coil , to the electronic switch K4 to form a loop. If the opposite excitation magnetic field needs to be generated, the electromagnetic flowmeter control board controls the electronic switches K2 and K3 to conduct, and the excitation current flows from the constant current source S through the electronic switch K3, from point B to the excitation coil A point, to the electronic switch K2. circuit. If the control board of the electromagnetic flowmeter makes the four electronic switches all non-conductive, the excitation coil will not pass the excitation current, and the electromagnetic flowmeter will not generate an excitation magnetic field. The above is the excitation principle of the electromagnetic flowmeter. A well-insulated excitation coil can make the excitation current of the electromagnetic flowmeter stable and reliable without any shunt, thereby maintaining the accuracy and stability of the magnetic field strength. Therefore, it is of great significance to test the insulation resistance of the excitation coil. However, the existing technology A more convenient and practical insulation resistance test circuit for the excitation coil is not provided in the paper.
实用新型内容 Utility model content
本实用新型所要解决的技术问题是针对上述现有技术提供一种方便实用的励磁线圈的绝缘电阻测试电路。 The technical problem to be solved by the utility model is to provide a convenient and practical insulation resistance test circuit for excitation coils in view of the above-mentioned prior art.
本实用新型解决上述技术问题所采用的技术方案为：一种电磁流量计自行对励磁线圈的绝缘电阻测试电路，其特征在于：包括第一电阻、第二电阻、第一运算放大器、第二运算放大器、第三电阻和第四电阻，其中第一运算放大器、第二运算放大器的放大倍数均为1，且第一运算放大器为高输入阻抗运算放大器，第一电阻的第一端与恒流源相连，第一电阻的第二端与励磁线圈的绝缘电阻的第一端连接，励磁线圈的绝缘电阻的第二端接地，同时第一电阻的第二端还与第二电阻的第一端连接，第二电阻的第二端与第一运算放大器的同相输入端连接，第一运算放大器的反相输入端与第一运算放大器的输出端连接，第一运算放大器的输出端与第三电阻的第一端连接，第三电阻的第二端与第四电阻的第一端连接，第四电阻的第二端接地，同时第四电阻的第一端与第二运算放大器的同相输入端连接，第二运算放大器的反相输入端与第二运算放大器的输出端连接， 第二运算放大器的输出端与电磁流量计内部的A/D转换电路输入端连接。 The technical solution adopted by the utility model to solve the above-mentioned technical problems is: an electromagnetic flowmeter self-test circuit for the insulation resistance of the excitation coil, which is characterized in that it includes a first resistor, a second resistor, a first operational amplifier, a second operational amplifier amplifier, the third resistor and the fourth resistor, wherein the amplification factor of the first operational amplifier and the second operational amplifier is 1, and the first operational amplifier is a high input impedance operational amplifier, the first end of the first resistor is connected to the constant current source The second end of the first resistor is connected to the first end of the insulation resistance of the excitation coil, the second end of the insulation resistance of the excitation coil is grounded, and the second end of the first resistor is also connected to the first end of the second resistor , the second terminal of the second resistor is connected to the non-inverting input terminal of the first operational amplifier, the inverting input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier, the output terminal of the first operational amplifier is connected to the third resistor The first end is connected, the second end of the third resistor is connected to the first end of the fourth resistor, the second end of the fourth resistor is grounded, and the first end of the fourth resistor is connected to the non-inverting input end of the second operational amplifier, The inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier, and the output terminal of the second operational amplifier is connected to the input terminal of the A/D conversion circuit inside the electromagnetic flowmeter.
作为改进，本实用新型还包括第一二极管和第二二极管，其中第一二极管的负极与励磁线圈的绝缘电阻的第一端连接，第一二极管的正极与第二二极管的负极连接，第二二极管的正极与励磁线圈的绝缘电阻的第二端连接。第一二极管和第二二极管与励磁线圈的绝缘电阻进行并联，其主要作用是保护励磁线圈和励磁回路中的电子开关，而第一二极管和第二二极管的选择应保证励磁回路中的电子开关导通瞬间和断开瞬间产生的脉冲高压通过第一二极管和第二二极管的抑制，从而实现保护励磁线圈和电子开关，并且第一二极管和第二二极管在电子开关导通时，不会分流流经励磁线圈的励磁电源。 As an improvement, the utility model also includes a first diode and a second diode, wherein the negative pole of the first diode is connected to the first end of the insulation resistance of the excitation coil, and the positive pole of the first diode is connected to the second end of the insulation resistance of the excitation coil. The cathode of the diode is connected, and the anode of the second diode is connected to the second end of the insulation resistance of the excitation coil. The first diode and the second diode are connected in parallel with the insulation resistance of the excitation coil, and its main function is to protect the electronic switch in the excitation coil and the excitation circuit, and the selection of the first diode and the second diode should be Ensure that the pulse high voltage generated by the electronic switch in the excitation circuit at the moment of on and off is suppressed by the first diode and the second diode, so as to realize the protection of the excitation coil and the electronic switch, and the first diode and the second diode The second diode will not shunt the excitation power flowing through the excitation coil when the electronic switch is turned on.
与现有技术相比，本实用新型的优点在于：通过本实用新型提供的电路，能使电磁流量计自行对励磁线圈的绝缘电阻进行测试。 Compared with the prior art, the utility model has the advantage that the electromagnetic flowmeter can test the insulation resistance of the excitation coil by itself through the circuit provided by the utility model.
附图说明 Description of drawings
图1为电磁流量计的励磁回路电路图。 Figure 1 is the circuit diagram of the excitation circuit of the electromagnetic flowmeter.
图2为本实用新型实施例中励磁线圈的绝缘电阻测试电路的电路原理图。 Fig. 2 is a schematic circuit diagram of the insulation resistance test circuit of the excitation coil in the embodiment of the present invention.
具体实施方式 Detailed ways
以下结合附图实施例对本实用新型作进一步详细描述。 The utility model is described in further detail below in conjunction with the accompanying drawings.
如图2所示的一种电磁流量计自行对励磁线圈的绝缘电阻测试电路，其包括第一电阻R1、第二电阻R2、第一运算放大器U1、第二运算放大器U2、第三电阻R3和第四电阻R4，其中第一运算放大器U1、第二运算放大器U2的放大倍数均为1，且第一运算放大器U1为高输入阻抗运算放大器，第一电阻R1的第一端与恒流源S相连，第一电阻R1的第二端与励磁线圈的绝缘电阻RM的第一端连接，励磁线圈的绝缘电阻RM的第二端接地，同时第一电阻R1的第二端还与第二电阻R2的第一端连接，第二电阻R2的第二端与第一运算放大器U1的同相输入端连接，第一运算放大器U1的反相输入端与第一运算放大器U1的输出端连接，第一运算放大器U1的输出端与第三电阻R3的第一端连接，第三电阻R3的第二端与第四电阻R4的第一端连接，第四电阻R4的第二端接地，同时第四电阻R4的第一端与第二运算放大器U2的同相输入端连接，第二运算放大器U2的反相输入端与第二运算放大器U2的输出端连接，第二运算放大器U2的输出端与电磁流量计内部的A/D转换电路输入端连接。 As shown in Figure 2, an electromagnetic flowmeter self-tests the insulation resistance of the excitation coil, which includes a first resistor R1, a second resistor R2, a first operational amplifier U1, a second operational amplifier U2, a third resistor R3 and The fourth resistor R4, wherein the amplification factors of the first operational amplifier U1 and the second operational amplifier U2 are both 1, and the first operational amplifier U1 is a high input impedance operational amplifier, and the first end of the first resistor R1 is connected to the constant current source S The second end of the first resistor R1 is connected to the first end of the insulation resistance RM of the excitation coil, the second end of the insulation resistance RM of the excitation coil is grounded, and the second end of the first resistor R1 is also connected to the second end of the second resistor R2 The first terminal of the second resistor R2 is connected to the non-inverting input terminal of the first operational amplifier U1, the inverting input terminal of the first operational amplifier U1 is connected to the output terminal of the first operational amplifier U1, and the first operational The output end of the amplifier U1 is connected to the first end of the third resistor R3, the second end of the third resistor R3 is connected to the first end of the fourth resistor R4, the second end of the fourth resistor R4 is grounded, and the fourth resistor R4 The first terminal of the second operational amplifier U2 is connected to the non-inverting input terminal of the second operational amplifier U2, the inverting input terminal of the second operational amplifier U2 is connected to the output terminal of the second operational amplifier U2, and the output terminal of the second operational amplifier U2 is connected to the inside of the electromagnetic flowmeter The A/D conversion circuit input terminal connection.
本实施例还包括第一二极管D1和第二二极管D2，其中第一二极管的负极与励磁线圈的绝缘电阻的第一端连接，第一二极管的正极与第二二极管的负极连接，第二二极管的正极与励磁线圈的绝缘电阻的第二端连接。第一二极管和第二二极管与励磁线圈的绝缘电阻进行并联，其主要作用是保护励磁线圈和励磁回路中的电子开关，而第一二极管和第二二极管的选择应保证励磁回路中的电子开关导通瞬间和断开瞬间产生的脉冲高 压通过第一二极管和第二二极管的抑制，从而实现保护励磁线圈和电子开关，并且第一二极管和第二二极管在电子开关导通时，不会分流流经励磁线圈的励磁电源。 This embodiment also includes a first diode D1 and a second diode D2, wherein the cathode of the first diode is connected to the first end of the insulation resistance of the excitation coil, and the anode of the first diode is connected to the second end of the second diode. The cathode of the second diode is connected to the cathode, and the anode of the second diode is connected to the second end of the insulation resistance of the excitation coil. The first diode and the second diode are connected in parallel with the insulation resistance of the excitation coil, and its main function is to protect the electronic switch in the excitation coil and the excitation circuit, and the selection of the first diode and the second diode should be Ensure that the pulse high voltage generated by the electronic switch in the excitation circuit at the moment of on and off is suppressed by the first diode and the second diode, so as to realize the protection of the excitation coil and the electronic switch, and the first diode and the When the electronic switch is turned on, the second diode will not shunt the excitation power flowing through the excitation coil.
电磁流量计控制板控制四个电子开关K1、K2、K3、K4都不导通时测试励磁线圈L的绝缘电阻RM，若励磁线圈L的绝缘电阻RM下降，第一电阻R1和励磁线圈L的绝缘电阻RM对电源电压VS分压，即B点电位为VM，显然，由于VS和R1已知，则通过测试VM即可获得励磁线圈L的绝缘电阻RM。然后电磁流量计内部的A/D转换电路输入端的检测电压往往在0～+2.5V，而通常VM的值超过+2.5V，超出电磁流量计内部的A/D转换电路的检测上限，并且电子开关K1～K4的导通瞬间和断开瞬间将产生脉冲高压，该脉冲虽被过压保护元件——第一二极管D1和第二二极管D2抑制，但仍可能超出第一运算放大器的正常输入范围；因此第二电阻为保护电阻，由于第一运算放大器U1为高输入阻抗的同相运算放大器，且放大倍数为1，因此第一运算放大器U1同相输入端电压约等于VM，第一运算放大器U1输出端电压也约等于VM，电磁流量计内部的A/D转换电路输入端检测到的电压为V0，由于第二运算放大器U2的放大倍数为1，第三电阻和第四电阻对第二运算放大器U2分压，以保证第二运算放大器U2输出电压V0的动态范围在A/D转换电路的输入范围内，第二运算放大器U2和第一运算放大器U1一样起阻抗匹配作用。作为高输入阻抗的同相放大器，V0＝VR4，因此通过测得的V0，即可计算得到励磁线圈L的绝缘电阻RM。 The electromagnetic flowmeter control board controls the four electronic switches K1, K2, K3, and K4 to test the insulation resistance RM of the excitation coil L. If the insulation resistance RM of the excitation coil L decreases, the first resistance R1 and the excitation coil L The insulation resistance RM divides the power supply voltage VS, that is, the potential of point B is VM. Obviously, Since VS and R1 are known, the insulation resistance RM of the excitation coil L can be obtained by testing VM. Then the detection voltage of the input terminal of the A/D conversion circuit inside the electromagnetic flowmeter is often 0~+2.5V, and usually the value of VM exceeds +2.5V, which exceeds the detection limit of the A/D conversion circuit inside the electromagnetic flowmeter, and the electronic The moment of turn-on and turn-off of switches K1~K4 will generate pulse high voltage. Although the pulse is suppressed by the overvoltage protection components—the first diode D1 and the second diode D2, it may still exceed the voltage of the first operational amplifier. Therefore, the second resistor is a protective resistor. Since the first operational amplifier U1 is a non-inverting operational amplifier with high input impedance, and the amplification factor is 1, the voltage at the non-inverting input terminal of the first operational amplifier U1 is approximately equal to VM, and the first The voltage at the output terminal of the operational amplifier U1 is also approximately equal to VM, and the voltage detected at the input terminal of the A/D conversion circuit inside the electromagnetic flowmeter is V0, Since the amplification factor of the second operational amplifier U2 is 1, the third resistor and the fourth resistor divide the voltage of the second operational amplifier U2 to ensure that the dynamic range of the output voltage V0 of the second operational amplifier U2 is within the input range of the A/D conversion circuit Inside, the second operational amplifier U2 plays the same role of impedance matching as the first operational amplifier U1. As a non-inverting amplifier with high input impedance, V0=V R4 , so the insulation resistance RM of the exciting coil L can be calculated from the measured V0.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10712184B1 (en) | 2019-01-09 | 2020-07-14 | Georg Fischer Signet Llc | Magnetic flowmeter assembly having independent coil drive and control system |
| CN113624306A (en) * | 2021-09-06 | 2021-11-09 | 宁波水表(集团)股份有限公司 | Fault detection device and method for electromagnetic water meter sensor |
| US11365995B2 (en) | 2018-09-28 | 2022-06-21 | Georg Fischer Signet Llc | Magnetic flowmeter including auxiliary electrodes upstream and downstream of the pair of measuring electrodes and an adjustable brace |
| CN115507905A (en) * | 2022-05-23 | 2022-12-23 | 浙江迪元仪表有限公司 | An electromagnetic water meter for measuring the insulation resistance of the sensor to the ground |
-
2015
- 2015-06-30 CN CN201520473027.2U patent/CN204740058U/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11365995B2 (en) | 2018-09-28 | 2022-06-21 | Georg Fischer Signet Llc | Magnetic flowmeter including auxiliary electrodes upstream and downstream of the pair of measuring electrodes and an adjustable brace |
| US10712184B1 (en) | 2019-01-09 | 2020-07-14 | Georg Fischer Signet Llc | Magnetic flowmeter assembly having independent coil drive and control system |
| CN113624306A (en) * | 2021-09-06 | 2021-11-09 | 宁波水表(集团)股份有限公司 | Fault detection device and method for electromagnetic water meter sensor |
| CN113624306B (en) * | 2021-09-06 | 2023-11-14 | 宁波水表(集团)股份有限公司 | Fault detection device and method for electromagnetic water meter sensor |
| CN115507905A (en) * | 2022-05-23 | 2022-12-23 | 浙江迪元仪表有限公司 | An electromagnetic water meter for measuring the insulation resistance of the sensor to the ground |
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