CN210037974U

CN210037974U - Insulation monitor

Info

Publication number: CN210037974U
Application number: CN201920425957.9U
Authority: CN
Inventors: 艾龙家
Original assignee: Zhejiang Kaidu Intelligent Equipment Co Ltd
Current assignee: Zhejiang Kaidu Intelligent Equipment Co Ltd
Priority date: 2019-03-29
Filing date: 2019-03-29
Publication date: 2020-02-07
Anticipated expiration: 2029-03-29

Abstract

The utility model discloses an insulation monitor, including the MCU that is used for synthesizing signal processing, be used for producing signal generation circuit, a signal injection circuit for detecting insulating signal, insulation resistance measuring module, switching value output module, be used for showing data information's colored man-machine interface and the RS485 and the Mobus communication module that are used for the communication, the utility model discloses a design a controllable frequency's low-frequency pulse signal source to on being surveyed system electric wire netting (system) with signal transmission, this signal source and being surveyed the insulation resistance formation test circuit between electric wire netting and the ground, receiving circuit passes through specific processing algorithm, removes the influence of exchanging such as electric wire netting and interfering signal through the wave filter, obtains insulation resistance value according to ohm's law at last. The transmitting signal is controlled by the main control chip, so that the influence of the distributed capacitance of the system can be effectively adapted. Therefore, the device has stronger stability and anti-interference performance and higher test precision.

Description

Insulation monitor

Technical Field

The utility model relates to a monitor specifically is an insulating monitor.

Background

The insulation monitoring instrument is designed according to the requirement, the insulation monitoring instrument is developed in 2 generations, the current insulation monitoring instrument can be applied to any occasion from 0V to 1150V, the product universality is strong, and the insulation monitoring instrument is simple and convenient to install and is a preferred domestic model for replacing the imported similar insulation monitoring instrument.

The existing insulation monitor relies on the electrical signal (voltage or current) of the system under test, so that the accuracy and stability of the measurement are limited by the system under test, and therefore, the requirement of higher-end test cannot be met.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide an insulating monitor to solve the problem that proposes among the above-mentioned background art.

In order to achieve the above object, the utility model provides a following technical scheme:

the utility model provides an insulation monitor, is including the MCU that is used for synthesizing signal processing, be used for producing signal generator circuit, be used for detecting the signal injection circuit of insulating signal, insulation resistance measurement module, switching value output module, be used for the colored man-machine interface of display data information and the RS485 and the Mobus communication module that are used for the communication, MCU connects insulation resistance measurement module, switching value output module, colored man-machine interface and RS485 and Mobus communication module respectively through the interface that sets up on it, and the input of signal injection circuit is connected to the output of signal generator circuit, and the output of signal injection circuit connects insulation resistance measurement module.

As a further technical solution of the present invention: the MCU is also connected with the power module, the data storage module and the touch key.

As a further technical solution of the present invention: the insulation resistance measurement module comprises a resistor R1, a resistor R2, a capacitor C14, a resistor R4 and a diode D1, one end of the resistor R1 is connected with an input end IN, the other end of the resistor R1 is connected with a resistor R2, the other end of the resistor R2 is connected with a resistor R3, a resistor R4 and a capacitor C14, the other end of the resistor R3 is connected with the cathode of the diode D1 and the capacitor C15, and the other end of the capacitor C14 is connected with the other end of the resistor R4, the anode of the diode D1, the other end of the capacitor C14 and the ground.

As a further technical solution of the present invention: and a filtering and amplifying circuit is also arranged between the insulation resistance measuring module and the MCU.

As a further technical solution of the present invention: the filtering amplification circuit is formed by connecting a plurality of operational amplifiers in series.

As a further technical solution of the present invention: the testing device is further connected to the MCU and comprises a diode D11, a triode Q1 and a relay K1, the base electrode of the triode Q1 is connected with the MCU through a resistor R16, the collector electrode of the triode Q1 is connected with the anodes of the relay K1 and the diode D11, and the cathode of the diode D11 is connected with the other end of the relay K1 and a 12V power supply.

Compared with the prior art, the beneficial effects of the utility model are that: the utility model discloses a design a controllable frequency's low frequency pulse signal source to on being surveyed system electric wire netting (system) with signal transmission, this signal source and being surveyed the insulation resistance between electric wire netting and the ground and form test circuit, receiving circuit passes through specific processing algorithm, removes the influence of exchanging such as electric wire netting and interfering signal through the wave filter, obtains insulation resistance value according to ohm law at last. The transmitting signal is controlled by the main control chip, so that the influence of the distributed capacitance of the system can be effectively adapted. Therefore, the device has stronger stability and anti-interference performance and higher test precision.

Drawings

Fig. 1 is a working principle diagram of the present invention.

Fig. 2 is a block diagram of the present invention.

Fig. 3 is a circuit diagram of the insulation resistance measurement module.

Fig. 4 is a circuit diagram of the filter amplifier circuit.

Fig. 5 is a circuit diagram of a self-test circuit.

Fig. 6 is a flowchart of the procedure of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Example 1: referring to fig. 1-6, an insulation monitor comprises an MCU, a signal generating circuit, a signal injection circuit, an insulation resistance measuring module, a switching value output module, a data storage module, a color human-computer interface, a touch key, a power module, an RS485 and Mobus communication module, wherein the MCU selects a 32-bit ARM core-M3 kernel chip (STM32F103VET6) produced by ST corporation, the chip has high processing speed and main frequency of 72MHz, and has rich on-chip and peripheral resources, a 12-bit a-D conversion module with multiple channels, and a plurality of SPI, IIC, RS232 and other communication interfaces, thereby greatly simplifying the design of peripheral circuits. The instrument is provided with two paths of relay outputs except for the most basic measuring system of the ground resistance, and a color liquid crystal module with 320 x 240 image numbers is used as a man-machine interface, so that the man-machine interface is more friendly; the system has RS485 communication, follows Modbus-RTU protocol, has an alarm function, and can set each parameter by oneself.

The MCU is respectively connected with the insulation resistance measuring module, the switching value output module, the data storage module, the color human-computer interface, the light touch key, the power module, the RS485 and the Mobus communication module through the interfaces arranged on the MCU, the output end of the signal generating circuit is connected with the input end of the signal injection circuit, and the output end of the signal injection circuit is connected with the insulation resistance measuring module.

In ac IT systems, the voltage often fluctuates somewhat. Therefore, the insulation monitor needs to have a voltage reduction circuit inside to meet the different voltages. After the insulation monitor is powered on, the signal injection module can continuously inject a specific square wave voltage into a monitored system, the system measures a resistor R1, a resistor R2 and a resistor Rf, the values of R1 and R2 are known, so that the resistor Rf can be obtained by subtracting the resistor R1 and the resistor R2, and a measurement circuit is shown in FIG. 3.

In an actual power system, due to the existence of a high-frequency signal, interference may be caused to signal sampling, so a filtering process is performed on a sampled signal, the design adopts a fourth-order low-pass filter circuit, the circuit cutoff characteristic is good, the attenuation rate of a curve is steep, and the measurement accuracy is improved, wherein the filter circuit is as shown in fig. 4:

since the circuit consists of two identical second-order circuits, only one circuit needs to be analyzed. For the first second order circuit: when the frequency f is 0, both C1 and C6 are open-circuited, and the pass-band amplification factor Aup is-R1/R6 (1)

Let M be the point where R6, C6, and R7 intersect, the input voltage signal be Ui, and the output voltage signal be Uo. According to the virtual short and the virtual break of the amplifier, for M points, the current equation is as follows:

wherein

Solving the above two equations yields:

the second-order low-pass filter circuit model of the voltage-controlled voltage source is compared to obtain:

in the formula (f)₀Representing the cut-off frequency, substituting the data to obtain f₀Approximately 2.567Hz, which allows frequencies below f₀Will attenuate to a different degree than waveforms above that frequency.

Embodiment 2, on the basis of embodiment 1, the insulation monitor further comprises a testing device to test whether the insulation monitoring device can perform its function. Referring to fig. 5, the MCU sends a signal, amplifies the signal via the transistor Q1, and drives the relay K1 to select a connection test mode.

The utility model discloses a theory of operation is: as shown in fig. 1, L1, L2, and L3 are three-phase power supplies, and the three-phase power supplies enter the system through an isolation transformer. The resistor R1, the resistor R2 and the resistor R3 are loads in the system; the resistance Rf is an insulation resistance to the ground; the resistor Rx is a divider resistor; the positive and negative 12V square wave signal generators in the insulation monitor are respectively connected with the isolated three-phase power supply.

Normally, the system is insulated from ground, and the resistance Rf is infinite; when the system has an insulation failure, such as the direct contact between the system conductor and the housing, the system is directly connected to the ground, and the resistance Rf is equivalent to 0. The insulation monitor injects square wave signals into the system, the square wave signals enter the insulation monitor through the resistor Rf to form a closed loop, and the magnitude of the resistor Rf can be calculated through ohm's law. The square wave signal can effectively avoid the influence caused by the system capacitance, so that the measured impedance has higher accuracy, and the insulation performance of the system can be well reflected.

It is obvious to a person skilled in the art that the invention is not restricted to details of the above-described exemplary embodiments, but that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. The utility model provides an insulation monitor, is including the MCU that is used for synthesizing signal processing, be used for producing signal generator circuit, be used for detecting the signal injection circuit of insulating signal, insulation resistance measurement module, switching value output module, be used for the colored man-machine interface of display data information and the RS485 and the Mobus communication module that are used for the communication, its characterized in that, MCU connects insulation resistance measurement module, switching value output module, colored man-machine interface and RS485 and Mobus communication module respectively through the interface that sets up on it, and the input of signal injection circuit is connected to the output of signal generator circuit, and the output of signal injection circuit connects insulation resistance measurement module.

2. The insulation monitor according to claim 1, further comprising a power module, a data storage module and a touch key, wherein the MCU is further connected to the power module, the data storage module and the touch key.

3. The insulation monitor as claimed IN claim 1, wherein the insulation resistance measuring module comprises a resistor R1, a resistor R2, a capacitor C14, a resistor R4 and a diode D1, one end of the resistor R1 is connected to the input terminal IN, the other end of the resistor R1 is connected to the resistor R2, the other end of the resistor R2 is connected to the resistor R3, the resistor R4 and the capacitor C14, the other end of the resistor R3 is connected to the cathode of the diode D1 and the capacitor C15, and the other end of the capacitor C14 is connected to the other end of the resistor R4, the anode of the diode D1, the other end of the capacitor C14 and ground.

4. The insulation monitor according to claim 1, wherein a filter amplifier circuit is further disposed between the insulation resistance measuring module and the MCU.

5. The insulation monitor of claim 4, wherein said filter-amplifier circuit comprises a plurality of operational amplifiers connected in series.

6. An insulation monitor as claimed in any one of claims 1 to 5, wherein the MCU is further connected to a testing device, the testing device comprises a diode D11, a transistor Q1 and a relay K1, the base of the transistor Q1 is connected to the MCU through a resistor R16, the collector of the transistor Q1 is connected to the anode of the relay K1 and the diode D11, and the cathode of the diode D11 is connected to the other end of the relay K1 and a 12V power supply.