A method for detecting leakage current in an industrial robot electrical cabinet

Abstract

This invention discloses a leakage current detection method for an industrial robot electrical cabinet, including port P1. The leakage current detection method is as follows: Current flows through the PE (protective earth) and through the current transformer L1. When the current I1 flowing through the primary and secondary sides of L1 increases; the principle of the current transformer is: N1 / N2 = I2 / I, resulting in I2 = I1*N1 / N2; therefore, the current I2 flowing through the secondary side of the current transformer L1 also increases; when there is no leakage current in the cabinet, there is no current or the current on the PE is very small, U- < 5V; the voltage at the non-inverting terminal of the comparator is greater than the voltage at the inverting terminal, Vout = H, and the output pin 1 of the LM393D is high, and the LED is constantly lit. Based on the characteristics of the electrical cabinet, this invention eliminates the need for a leakage current switch. By designing a current detection circuit flowing through the PE, it determines whether there is a leakage current in the equipment. Its setup cost is lower than that of installing a leakage current protection device.

Description

Technical Field

[0001] This invention relates to the field of leakage current detection technology for industrial robot electrical cabinets, specifically a method for detecting leakage current in industrial robot electrical cabinets. Background Technology

[0002] Currently, leakage current devices in robot electrical cabinets are mainly implemented through leakage current protectors. Existing conventional leakage protection mainly relies on the sum of the inflow and outflow currents to be zero. Sampling has requirements for the incoming line relationship. Excluding the incoming line relationship, leakage problems of weak current can also be detected. In order to avoid false tripping, the leakage switch is designed with a complex identification and processing process. The disconnected current is a range and is not quantified.

[0003] The existing leakage current detection methods for industrial robot electrical cabinets have the following drawbacks:

[0004] Existing residual current devices (RCDs) are expensive, cannot accurately calculate the magnitude of leakage current, and are prone to misjudgment. Summary of the Invention

[0005] The purpose of this invention is to provide a leakage current detection method for an industrial robot electrical cabinet, so as to solve the existing problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a leakage current detection method for an industrial robot electrical cabinet, including port P1, wherein the leakage current detection method is as follows:

[0007] Current flows through the PE and through the current transformer L1. When the current I1 flowing through the primary and secondary sides of L1 increases; according to the principle of the current transformer: N1 / N2=I2 / I, we get I2=I1*N1 / N2; therefore, the current I2 flowing through the secondary side of the current transformer L1 also increases.

[0008] When there is no leakage in the electrical cabinet, and there is no current or very little current on the PE, U-<5V;

[0009] When the voltage at the non-inverting input of the comparator is greater than the voltage at the inverting input, Vout = H. The output pin 1 of the LM393D is high, and the LED is always on.

[0010] Preferably, when current flows through PE, causing the voltage value U-=R5*(N1 / N2)*I1 to reach the comparison point, i.e. U->5V, the voltage at the non-inverting terminal of the comparator is less than the voltage at the inverting terminal, Vout=L, and the output pin 1 of the LM393D is low, and the LED is off.

[0011] Preferably, when the LED light is seen to be off, it can be determined that the current flowing through the PE exceeds the set threshold, and Vout will feed back a signal for system protection.

[0012] Preferably, when the system reads a protection signal, it disconnects the downstream device, the current of PE decreases until U- < 5V, the indicator light will light up again, and Vout output will be L.

[0013] Preferably, the input voltage U- at the inverting terminal of pin 2 of the comparator LM393D is U-=R5*(N1 / N2)*I1.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] 1. Based on the characteristics of the electrical cabinet, this invention eliminates the need for a leakage current switch. By designing a current detection circuit that detects the current flowing through the PE (protective earth) device, it can determine whether there is a leakage current in the equipment. Its setup cost is lower than that of installing a leakage current protection device. At the same time, it can accurately calculate the leakage current, and the threshold can be selected, avoiding the limitation of only being able to indicate abnormalities within a certain current range (such as 2In to 4In). Furthermore, it uses a magnetic element to detect the current of the PE device and switches between different current types through a comparison circuit. When the current flowing through the PE device exceeds the threshold, an alarm and protection mechanism can be activated to ensure the safe operation of the robot. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the leakage current detection principle of the present invention;

[0017] Figure 2 This is a table of device models for the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] Please see Figure 1 and Figure 2 The present invention provides an embodiment of a leakage current detection method for an industrial robot electrical cabinet, including port P1, and the leakage current detection method is as follows.

[0021] In Example 1, current flows through the PE and through the current transformer L1. When the current I1 flowing through the primary and secondary sides of L1 increases; according to the principle of the current transformer: N1 / N2=I2 / I1, we get I2=I1*N1 / N2; then the current I2 flowing through the secondary side of the current transformer L1 also increases.

[0022] Example 2: When there is no leakage in the electrical cabinet, and there is no current or very little current on the PE, U- < 5V;

[0023] When the voltage at the non-inverting input of the comparator is greater than the voltage at the inverting input, Vout = H. The output pin 1 of the LM393D is high, and the LED is always on.

[0024] In Example 3, when current flows through PE, causing the voltage value of U-=R5*(N1 / N2)*I1 to reach the comparison point, i.e., U->5V, the voltage at the non-inverting terminal of the comparator is less than the voltage at the inverting terminal, Vout=L, and the output pin 1 of the LM393D outputs a low level, turning off the LED.

[0025] In Example 4, if the electrical appliances inside the cabinet are disconnected, the current flowing through PE from P decreases. When the current of PE is detected to be less than the set threshold, it will return to the state of U-<5V at the inverting terminal, at which point the LED light will illuminate.

[0026] Example 5: If the back-end electrical appliances are not checked, steps (3) and (4) will repeat. When the back-end equipment is disconnected, the current of PE decreases until U- < 5V, the voltage of the non-inverting input of the comparator > the voltage of the inverting input, Vout = H, the output pin 1 of LM393D is high, the LED is always on, and the indicator light will light up again. If the problem is not found, restart the electrical appliance. When the current on PE exceeds the threshold, the voltage value of U- = R5*(N1 / N2)*I1 reaches the comparison point, that is, when U->5V, the voltage of the non-inverting input of the comparator < the voltage of the inverting input, Vout = L, the output pin 1 of LM393D is low, the LED is off, and the indicator light LED will frequently turn on and off depending on whether the electrical appliance is used, resulting in a flickering phenomenon.

[0027] Example 6: If the LED light is seen to be off or flashing, it is determined that the leakage current of the device exceeds the threshold. Professional personnel are required to determine whether the threshold setting is inappropriate or whether there is an abnormality.

[0028] Example 7: When the LED returns to its normally lit state, it indicates that the leakage current of the system is within a reasonable range and the equipment can be used normally.

[0029] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0030] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for detecting leakage current in an industrial robot electrical cabinet, comprising port P1, characterized in that, The leakage current detection method is as follows: Current flows through the PE and through the current transformer L1. When the current I1 flowing through the primary and secondary sides of L1 increases; according to the principle of the current transformer: N1 / N2=I2 / I, we get I2=I1*N1 / N2; therefore, the current I2 flowing through the secondary side of the current transformer L1 also increases. When there is no leakage in the electrical cabinet, and there is no current or very little current on the PE, U-<5V; When the voltage at the non-inverting input of the comparator is greater than the voltage at the inverting input, Vout=H, pin 1 of the LM393D outputs a high level, and the LED remains on. When current flows through PE, causing the voltage U-=R5*(N1 / N2)*I1 to reach the comparison point, i.e. U->5V, the voltage at the non-inverting input of the comparator is less than the voltage at the inverting input, Vout=L, and the output pin 1 of the LM393D is low, and the LED is off. When the LED light turns off, it can be determined that the current flowing through the PE exceeds the set threshold. At the same time, Vout will feed back a signal for system protection. When the system reads the protection signal, it disconnects the downstream device, the current of PE decreases until U- < 5V, the indicator light will light up again, and Vout output will be L.

2. The leakage current detection method for an industrial robot electrical cabinet according to claim 1, characterized in that: The input voltage U- at the inverting terminal of pin 2 of comparator LM393D is U-=R5*(N1 / N2)*I1.

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