Operation and maintenance of electrical equipment grounding devices - Solutions - Huaqiang Electronic Network

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

First, the use of maintenance electrical equipment misunderstanding (taking agricultural machinery as an example)
1. The "armature" and "magnetic field" terminals are reversed. The triple regulator "armature" and "magnetic field" terminals shall be connected to the generator "armature" and "magnetic field" terminals respectively. If you carelessly reverse the two wires, the output current of the generator will form a loop through a 1Ω resistor, which will be burned out due to excessive current.
2. The damaged diode continues to be used. When it is found that the silicon rectifier generator does not generate electricity or the charging current is very small, it may be caused by the damage of the diode. It should be replaced immediately after checking. If it is used continuously, it will cause one or two phases of the stator winding to burn out.
3. The electrolyte is not adjusted according to seasonal temperature changes. This will make the battery plate not work in the electrolyte with the best specific gravity, which will greatly shorten its service life. In addition, in the winter, it is easy to cause the electrolyte to freeze and swell the battery.
4. Silicon rectifier generators do not pay attention to the polarity of the ground when installing the battery. This will short-circuit the battery due to the conduction of the diode, causing the silicon diode to burn quickly. Therefore, when installing the battery, the positive and negative poles of the battery must be correctly distinguished, and the connection can be made after confirmation.
5. Remove the iron and iron from the regulator and the generator. The locomotive electrical system is a single-wire system, so many drivers mistakenly believe that the ground connection between the generator and the regulator can be saved (using the body as a ground connection). However, there are oil stains, paints, etc. on the body, and there is a certain resistance between the generator and the regulator, so that the current of the two parallel coils leading to the regulator cannot increase with the increase of the generator voltage, causing the white gold contact of the interceptor not to be Closed and 1Ω resistor burned out without charging. Therefore, the ground wire of the regulator and the generator should not be removed.
6. Flatten the regulator on the locomotive. It is not installed vertically as it is, which will cause the regulator's platinum contacts to vibrate due to uneven road surface or locomotive vibration, affecting power generation quality and stable operation.
7. Charging time is too long. The capacity of the battery is limited. If the battery continues to be charged after sufficient power, the stored energy will not increase, and the charging current is only in the electrolysis water. Long-term over-charging also causes the active material of the electrode plate to fall off and accelerate the self-discharge of the battery.
8. Add too much or too little electrolyte to the battery. The electrolyte added to the cell should be immersed in the plate for 10~15mm, so that there is enough sulfuric acid to participate in the chemical reaction. If too much is easy to overflow, corrode the surrounding parts; too little, the plates will be exposed, which not only reduces the battery capacity, but also exposes the exposed plates quickly.
9. The electrolyte is too concentrated. Some people think that the concentration of the electrolyte is large, and the number of ions participating in the electrochemical reaction increases, which increases the battery capacity. In fact, too thick electrolyte viscosity increases, the penetration speed decreases, and the internal resistance increases, causing the battery terminal voltage to drop and the capacity to decrease. Excessive electrolyte will also accelerate the corrosion of the separator and shorten the life of the battery. Therefore, the electrolyte should not be too concentrated. When the storage capacity is sufficient, the specific gravity of the electrolyte is preferably 1.28.
10. Do not pay attention to the clean appearance of the battery. There are often dust and other debris on the battery. These things mix with the spilled electrolyte, which will form a circuit between the positive and negative terminals of the battery to discharge the battery. Therefore, always clean the exterior of the battery and take care to avoid placing metal objects on its cover.
11. Use two batteries of different capacities in series. This use is harmful. Because two batteries of different capacities are used in series, the battery with a small capacity is often overcharged or discharged, thereby shortening its service life.
12. Short the generator armature to the magnetic field terminal with wires. When the regulator fails, some drivers short-circuit the generator armature and the magnetic field terminal with wires to isolate the regulator's regulating portion, and the through-current interceptor supplies power to the ammeter. In doing so, as the generator increases the voltage with the speed, the voltage is greatly increased, and the overvoltage is burned out using electrical equipment.
13. The electric horn is continuously energized for too long. The continuous energization time of the electric horn should not be too long. The squealing should not exceed 3 seconds, so as to avoid burning the contacts and the excitation coil due to excessive current, and also prevent the battery from being discharged excessively.
14. The use of the instrument light will not be switched on simultaneously with the rear light. Because the Dongfanghong-75 tractor instrument light is connected in parallel with the rear headlight, it must be connected to the rear light at the same time. Some drivers turn on the instrument light separately when the rear headlights are disconnected. As a result, the power of the lamp rises a lot due to the small power of the lamp, causing the instrument lamp to be burned.
15. When the lights are not used, do not remove the generator belt. Dongfanghong series crawler tractors and other small tractors equipped with permanent magnet alternators should be unloaded after the engine is turned off to prevent the engine from being stopped. This avoids insignificant wear of the generator bearings and reduces engine power consumption.
Second, the electrical equipment grounding device operation
1. Technical requirements for grounding devices
1.1 The grounding device of the transformer (1) is grounded. The grounding body of the grounding device of the electric station should be laid horizontally. The grounding body adopts round steel with a length of 2.5m, a diameter of not less than 12mm or an angle steel with a thickness of not less than 4mm, or a steel pipe with a thickness of not less than 4mm, and is connected by a flat steel with a section of not less than 25mm×4mm as a closed ring, and the outer edges are respectively The corners should be curved.
2 The grounding body should be buried outside the wall of the transformer (distribution), the distance should be no less than 3m, the buried depth of the grounding grid should exceed the thickness of the local frozen soil layer, and the minimum buried depth should not be less than 0.6m.
The main transformer of the 3 variable (with) electric station, its working ground and protective grounding, should be connected to the artificial grounding grid respectively.
4 The lightning rod (wire) should be equipped with an independent grounding device.
1.2 Protection of electrical equipment in flammable and explosive places 1 Electrical equipment, mechanical equipment, metal pipes and metal structures of buildings in flammable and explosive places should be grounded, and jumper wires should be laid at the pipe joints.
2 In the neutral grounding line below 1kv, when the line overcurrent protection is a fuse, the safety factor of the protection device is not less than 4. When it is a circuit breaker, the safety factor of action is not less than 2.
3 The connection between the grounding trunk and the grounding body shall not be less than two, and shall be connected to the grounding body at both ends of the building.
4 In order to prevent accidents caused by sparks when measuring the grounding resistance, it is necessary to carry out the measurement in a place where there is no danger of explosion, or to lead the measuring terminal to a place other than the inflammable and explosive place.
1.3 Grounding of DC equipment Due to the action of DC current, the metal corrosion is severe and the contact resistance is increased. Therefore, when installing the grounding device on the DC line, the following measures must be carefully considered.
1 For the grounding of DC equipment, the natural grounding body cannot be used as the PE wire or the grounding body and grounding wire of the repeated grounding, and cannot be connected to the natural grounding body.
2 The manual grounding body of the DC system shall have a thickness of not less than 5 mm, and the erosion shall be checked regularly.
1.4 Hand-held, mobile electrical equipment grounding Handheld, mobile electrical equipment grounding wire should be soft copper wire, its cross section is not less than 1.5mm2, to ensure sufficient mechanical strength. The connection between the grounding wire and the electrical equipment or grounding body should be bolted or a special clamp to ensure good contact and meet the requirements of dynamic and thermal stability under the action of short-circuit current.
2 When the grounding device is running, the grounding wire and the grounding body may be damaged or broken due to external force damage or corrosion. The grounding resistance will also change with the soil change. Therefore, the grounding device must be inspected and tested regularly.
2.1 Inspection cycle 1 The grounding device of the transformer is generally inspected once a year;
2 According to the specific conditions of the workshop or building, the operation of the grounding wire is generally checked once or twice a year;
3 The grounding devices of various lightning protection devices are inspected once a year before the thunderstorm season.
4 For the grounding device with corrosive soil, the grounding body under the ground should be inspected once every 3 years to 5 years according to the operation conditions;
5 The grounding wire of hand-held and mobile electrical equipment should be inspected before each use;
6 The grounding resistance of the grounding device is generally measured once every 1 to 3 years.
2.2 Inspection item 1 Check whether the contact points of the grounding devices are in good contact, with or without damage, breakage and corrosion.
2 For the soil zone containing chemical components such as heavy acid, alkali, salt, etc. (generally chemical production enterprises, pharmaceutical production enterprises and some food industry enterprises), the corrosion degree of the grounding body above 500 mm above the ground should be inspected.
3 When the soil resistivity is maximum (generally before the rainy season), measure the grounding resistance of the grounding device and analyze and compare the measurement results.
4 After the electrical equipment is overhauled, check the grounding wire connection, which is firm and reliable.
5 Check whether the electrical equipment is connected to the grounding wire, the grounding wire is connected to the grounding grid, and the grounding wire is connected to the grounding trunk.
Third, maintenance personnel requirements
1 Careful observation of the abnormal phenomena that can be found through the observation of the eyes are: rupture, broken line; deformation (expansion, contraction, bending); looseness; oil leakage, water leakage, air leakage; pollution; corrosion; wear; discoloration (scorch, silica gel) Discoloration, oil blackening; smoke (sparks); foreign matter with impurities; abnormal movements, etc.
2 ear hearing device generates vibration due to the action of alternating current and emits a unique sound, and presents a certain regularity. If you listen carefully to these sounds and master the characteristics of sound changes, you can judge whether the equipment is running normally by its high and low rhythm, the change of tone, the intensity of the volume, and whether it is accompanied by noise.
Most of the people can smell and accurately discern the insulation of electrical equipment due to overheating. When the duty officer enters the power distribution room to check the electrical equipment, if he smells the equipment overheating or the smell of the insulating material is burnt, he should start to check to see if there is any smoke and discoloration, and listen to whether there is any discharge. Flashing the sound until you find out why. Smell is also a method of discriminating sensitive to certain abnormalities and defects in electrical equipment.
3 Touch the operator with your hand to touch the device being inspected with your hand to determine the defects and abnormalities of the device. It should be emphasized that it is absolutely forbidden to touch the live high voltage equipment by hand. Through the hand touch, you can feel the temperature change and vibration of the equipment, such as the temperature change of the transformer, local heating; the heat and vibration of the relay can be checked by touch.
4 Understand the operating conditions The equipment maintenance personnel know the running status of the equipment to the operating personnel, the weather changes when the fault occurs, the people with the load are small, and the similar faults are recorded and solved in the past. Through these "questions", you can quickly grasp the most basic conditions of equipment operation, and it is convenient for maintenance personnel to quickly and completely handle accidents, avoid accidents and find work errors, extend power outage time, and expand the scope of accidents.