What is Insulation Resistance, Lightning Resistance, and Ground Resistance

Insulation resistance is the concept of electricity, which ensures the safety of electrical equipment, and will not cause leakage and breakdown equipment due to low insulation resistance.

Grounding resistance is the resistance encountered when an electric current flows from a grounding device into the earth and then flows through the earth to another grounding body or spreads to a distant place.

The lightning protection resistance is somewhat similar to the grounding resistance, which refers to the resistance encountered by the lightning protection grounding device into the earth and then flowing to another grounding body through the earth or spreading to a distance.

The difference between grounding resistance and lightning protection resistance is that lightning protection resistance refers to the output of lightning protection grounding device, and like the TN system in our power grid power supply, N line has low resistance to electricity, and IT system is N line to ground high impedance, these grounding resistors are not used for lightning protection, so they cannot be called lightning protection resistors.

The insulation resistance is the resistance between two live wires or one live wire and the ground wire, and the magnitude of this resistance value is a parameter to ensure the safe operation of the equipment.

The lightning protection resistance is the resistance between the lightning line and the ground, generally 10 ohms is qualified.

Grounding resistance is the resistance of the live part of the equipment to the ground, and the grounding resistance has different numerical regulations for different devices on different occasions, such as the grounding resistance of the electrical grounding system is 4 ohms, and the grounding resistance of the instrument computer is 1 ohm. Nowadays, the design is generally based on an integrated grounding system that requires a grounding resistance of 1 ohm.

Insulation resistance refers to the ratio of the DC voltage applied to the test sample to the leakage current (or conductive current) flowing through the test product at the critical voltage of the insulator, i.e., r= u ie

What is Insulation Resistance?

Insulation resistance: A DC voltage is applied to a dielectric. After a certain period of polarization, the corresponding leakage current flowing through the dielectric is called the insulation resistance.

Insulation resistance is the most basic insulation index of electrical equipment and electrical circuits. For the handover test of low-voltage electrical installations, the insulation resistance of motors, distribution equipment and distribution lines at room temperature is not less than that of operating equipment and wiring is not less than 1 trillion ohm kV). The insulation resistance of low-voltage electrical appliances and their connecting cables and secondary circuits should generally not be less than 1m; In a humid environment, it should not be lower; The insulation resistance of the small circuit and small bus is not less than 10m.

The insulation resistance of Class I hand-held power tools should not be less than 2m.

What is the ground resistance?

Ground resistance is the resistance encountered when an electric current flows from a grounding device into earth and then flows through the ground to another grounding body or travels to a distance. The unit of measurement is . The size of the grounding resistance can reflect the degree of contact between the electrical device and the earth, and reflect the scale of the grounding grid.

Ground resistance measurement methods include two-wire method, three-wire method, four-wire method, single-clamp method, and double-clamp method. Each of these five methods has its own characteristics. When actually measuring, try to choose the correct method and measuring instrument for measurement. The results are accurate.

What is DC Winding Resistance?

DC resistance is mainly used for DC resistance testing of inductive loads such as transformers, motors, CT PT, etc., and the measurement unit is m. For example, the measurement of the DC resistance of a transformer winding is a convenient and effective test to investigate the connection of the winding insulation and the current circuit. It can reflect the welding quality of the winding, the short circuit between the winding turns, the winding is broken or the lead is broken, the tap changer and the wire is not in good contact and other faults, in fact, it is also an effective means to judge whether the DC resistance of each phase winding is balanced, and whether the voltage regulating switch gear is correct.

DC resistance measurement methods include: current and voltage method, DC bridge method, three-phase winding simultaneous compression method. At present, DC resistance testers all use the DC bridge method, which requires the test current to be not less than 1A, and the measurement resistance value is very small.

High test currents are common: 1A, 3A, 10A, 20A, 40A, 50A, 100A, and these are only used for single-phase measurements.

What is Contact Resistance?

Contact resistance is a parameter that characterizes whether the connection of a conductive circuit is good, and the unit of measurement is . Each type of high-voltage circuit breaker specifies a range of values. If the resistance of the circuit exceeds the specified value, it is likely that the conductive circuit is poorly connected.

In the case of high-current operation, the local temperature rise at the time of contact fault increases. In serious cases, even a vicious cycle causes oxidation and burning, and the circuit breaker used in high-current operation needs to be paid more attention.

Contact resistance measurements, bridge measurements, and DC voltage drop measurements are not allowed. And the test current is greater than or equal to 100A. The contact resistance tester is used to measure the contact resistance of switchgear such as high-voltage switches and on-load switches, and can directly reflect the contact of the switch contacts.

Difference Between Ground Resistance and Insulation Resistance

Grounding resistance is the resistance encountered when the current flows into the earth from the grounding device and then flows to another grounding body or spreads to a distant place through the grounding device, it includes the resistance of the grounding wire and the grounding body itself, the contact resistance between the grounding body and the earth's resistance and the resistance of the earth between the two grounding bodies or the earth's resistance to infinity, and the size of the grounding resistance test data directly reflects the electrical device and""good degree of contact.

Insulation resistance is to test the DC resistance of the insulator under specified conditions, is the most basic insulation index for measuring electrical equipment and electrical circuits, because the resistance value of the test is in megohm, so it is called a megohmmeter.

1. The grounding resistance of independent lightning protection should be less than or equal to 10 ohms.

2. The grounding resistance of independent safety protection should be less than or equal to 4 ohms.

3. The independent AC working grounding resistance should be less than or equal to 4 ohms.

4. The grounding resistance of the independent DC industrial roller pin should be less than or equal to 4 ohms.

5. The anti-static grounding resistance is generally required to be less than or equal to 100 ohms.

6. The common grounding body (joint grounding) should not be greater than the grounding resistance of 1 ohm.

The shell of electrical equipment must be grounded, and there are generally the following requirements for its grounding:

1. The metal shell of the protected electrical equipment should be grounded separately.

2. The grounding of the metal shell of the electrical equipment of the protected electric single-beam crane should be separated from the grounding of the neutral point of the power supply.

Testing the leakage current between two conductors or between one conductor to ground to verify the reliability of the non-conductance between them is called insulation resistance test, and insulation resistance is divided into inter-wire insulation resistance: wire-to-wire (such as relative phase, relative zero, etc.) and insulation resistance to ground: (such as relative ground, zero to ground, equipment to ground, etc.).

The greater the insulation resistance value, the better, the more reliable the non-conductivity between them, and the insulation resistance is measured in megaohms. Generally, the interline requirements are more than megaohms, while the measured value is several hundred megaohms for large cables.

I don't know what you mean by ground resistance, if it is insulation resistance to ground, it is the above, if it is grounding resistance, then: grounding resistance test is to verify the conductivity of a conductor and the earth, such as lightning protection grounding, protective grounding, etc., the smaller the grounding resistance value, the better, the more reliable the conductivity between them and the ground, and the grounding resistance is in ohms. According to the grounding of different purposes, there are different requirements, generally between 1 30 ohms, the soil with good conductivity, such as good connection, are below Europe.

The accuracy of the grounding resistance requires at least 1% ohms.

There are three differences between insulation resistance and ground resistance:

1. Insulation resistance refers to the ability of an object to withstand the breakdown conduction of voltage, and the resistance to ground tests the conductivity between a conductor and the earth;

2. It is generally used for insulating objects and electrical appliances of different voltage levels in liquid rubber shops, in which the insulation objects have different insulation requirements, and the smaller the ground resistance value, the better, the more reliable the conductivity between the ground and the earth;

3. The insulation resistance value is as large as possible, the more reliable the non-conductivity between them, the insulation resistance is in megaohms, the general line is required to be above the megaohm, and the resistance to the ground is generally between 1 and 30 megaohms. Sedan car.

The value of lightning protection grounding resistance is determined according to the actual situation, and the sum of the grounding resistance of the grounding body or the natural grounding body is called the grounding resistance of the grounding device, and its value is equal to the ratio of the grounding voltage of the grounding device to the ground and the current flowing into the ground through the grounding body. At the same time, the grounding resistance is also a sign to measure the level of the grounding device.

It can be measured by the grounding resistance meter, and the grounding resistance Zheng Sansheng meter is used to measure the old ground resistance of the grounding device such as protective grounding, working grounding, anti-overvoltage grounding, anti-static grounding and lightning protection grounding, that is, the resistance presented when the grounding device flows through the power frequency current, including the grounding wire resistance, the grounding body resistance, the contact resistance between the grounding body and the earth and the earth dispersion resistance.

The lightning protection ground resistance is within 4 ohms.

The lightning protection ground resistance value refers to the ground resistance in the grounding system used to prevent lightning strikes. The resistance between the ground electrode and ground is the resistance between the ground electrode and the ground, which plays a key role in effectively introducing lightning or other currents into the ground.

According to the International Electrotechnical Commission (IEC) specifications, different types of grounding systems have different grounding resistance requirements. According to IEC 60364 standard, the grounding resistance of general buildings should be less than 10 ohms. For high-rise buildings, to better protect the building and people from lightning strikes, the ground resistance requirement is lower.

Ground resistance is generally required to be less than 5 ohms or less.

For locations that are very sensitive to electromagnetic interference and lightning strikes, such as medical facilities, electronic equipment manufacturing plants, etc., the ground resistance requirements are often more stringent and may need to be 1 ohm or less.

It should be noted that the measurement of grounding resistance needs to be carried out by professional testing instruments and should be carried out under appropriate geological and environmental conditions to ensure accuracy and reliability.

In short, the requirements for lightning protection grounding resistance value vary depending on different places and needs, but the grounding resistance is generally required to be less than 10 ohms. Specific requirements should be determined in accordance with the relevant standards and specifications and tested under appropriate conditions.

The role of lightning protection grounding resistors

1. Disperse lightning energy: When lightning hits buildings or other facilities, the lightning protection grounding resistance can effectively disperse the lightning energy to the ground through a good grounding connection. This avoids direct damage to buildings and equipment by lightning.

2. Protect the safety of equipment and personnel: The grounding resistance can safely guide the lightning energy to the ground, reducing the risk of lightning damage to the equipment and the injury of personnel. A safer working environment can be provided through a reasonable grounding system design.

3. Stable equipment operation: When lightning strikes a building or equipment, it may cause instantaneous changes in voltage and current, resulting in equipment failure or damage. With a good grounding system, these voltages and currents can be effectively dispersed and dissipated, and the stable operation of the equipment can be maintained.

4. Baoxingshan Combustion Protection Telecommunication System: Lightning protection and grounding resistance is very important for the normal operation of the telecommunication system. It can provide good grounding protection to avoid interference and damage to telecommunication equipment and communication lines by lightning.

Pro, strong electrical grounding insulation resistance is called resistance reason Insulation resistance is the concept of electricity, which ensures the safety of electrical equipment, and will not cause leakage and breakdown equipment because the insulation resistance is too low. Grounding resistance is the resistance encountered when the current flows into the earth from the grounding device and then flows to another grounding body or spreads to a distant place The lightning protection resistance is somewhat similar to the grounding resistance, which refers to the resistance encountered by the lightning protection grounding device into the earth and then through the earth flow section to another grounding body or to the distance. The difference between grounding resistance and lightning protection resistance is that lightning protection resistance refers to the output of lightning protection grounding device, and like the general TN system in our power grid power supply, N line to electricity low resistance, IT system is N line to ground high impedance, these grounding resistors are not used for lightning protection, so they can not be called lightning protection resistors<>

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