1. What are the main components of the oil-immersed transformer?
Answer: The main components of the transformer are: iron core, winding, fuel tank, oil pillow, respirator, explosion-proof tube, radiator, insulating sleeve, tap changer, gas relay, thermometer, net oil, etc.
2. What is a fully insulated transformer? What is a semi-insulated transformer?
Answer: Semi-insulation is the main insulation of the near-neutral part of the transformer. The insulation level is lower than the insulation level of the end winding. On the contrary, the insulation level of the first end and the end winding of the transformer is called full insulation.
3. What is the main role of the transformer in the power system?
A: The role of the power system in the transformer is to change the voltage to facilitate the transmission of power. After the voltage is boosted by the step-up transformer, the line loss can be reduced, the economy of power transmission can be improved, and the purpose of long-distance power transmission can be achieved. The step-down transformer can turn the high voltage into the voltage used by the user at all levels to meet the needs of the user.
4. What is the danger of casing cracking?
A: Cracks in the casing will reduce the insulation strength and cause further damage to the insulation until all breakdown. It is also possible for the casing to burst when the water in the crack freezes. It can be seen that the casing crack is very threatening to the safe operation of the transformer.
5. What is the difference between neutral point and zero point and zero line?
Answer: The common connection point where the first end (or the tail end) of the three-phase winding is connected together is called the neutral point of the power supply. When the neutral point of the power supply is well connected to the grounding device, the neutral point is called zero point; and the wire drawn from the zero point is called the zero line.
6. Why is the outdoor busbar connector prone to heat?
A: The outdoor busbars are often eroded by wind, rain, snow, sun, and ice. These can cause the busbar joint to accelerate oxidation and corrosion, so that the contact resistance of the joint increases and the temperature rises.
7. What are the chemical properties of SF6 gas?
A: SF6 gas is insoluble in water and transformer oil. It does not interact with oxygen, argon, aluminum and many other substances at hot temperatures. However, under the action of arc and corona, SF6 gas will decompose, producing low-fluorine compounds, which will cause damage to the insulating material, and these low-fluorine compounds are highly toxic gases. The decomposition reaction of SF6 has a lot to do with moisture, so there must be devitrification measures.
8. What is the role of the transformer's oil pillow?
Answer: When the volume of the transformer oil expands or shrinks with the change of the oil temperature, the oil pillow plays the role of oil storage and oil replenishment, which can ensure that the fuel tank is filled with oil, and at the same time, the transformer and the air contact surface are installed due to the oil pillow. Decrease, slowing down the rate of oil degradation. The oil level is also equipped with an oil level gauge on the side of the oil pillow to monitor the change in oil level.
9. Why should the iron core of the transformer be grounded?
Answer: The iron core and other accessories of the transformer are in the electric field around the winding. If it is not grounded, the iron core and other accessories will inevitably induce a certain voltage. Under the action of the applied voltage, when the induced voltage exceeds the discharge voltage to ground. , it will produce a discharge phenomenon. In order to avoid internal discharge of the transformer, the core is grounded.
10. Why should a set of ZnO arresters be installed between the power capacitor and its circuit breaker ?
Answer: The installation of ZnO arrester can prevent the operating overvoltage of power capacitors during pull-and-close operation and ensure the safe operation of electrical equipment.
11. What are the differences between the values ​​indicated by the energy meter and the power meter ?
Answer: The power meter indicates the number of electrical functions that are sent, transmitted, and consumed by the instantaneous transmitting, supplying, and powering equipment. The value of the energy meter is the cumulative amount of energy that is sent, transmitted, and consumed during a certain period of time.
12. What are the requirements for the battery of the parallel battery pack?
Answer: The electromotive force of each battery in the parallel battery should be equal. Otherwise, the battery with large electromotive force will discharge the battery with small electromotive force and form a circulation inside the battery pack. In addition, the internal resistance of each battery should also be the same, otherwise the discharge current of the battery with small internal resistance will be too large. Batteries with different old and new levels should not be used in parallel.
13. What is the role of the central signal device?
Answer: The central signal is a kind of signal device for monitoring the operation of substation electrical equipment. It emits sound and light signals according to the fault characteristics of electrical equipment, and informs the operation personnel to quickly find and make correct judgment and treatment to ensure the safe operation of the equipment.
14. Why is there still electricity in a short time when the cable line is powered off with an electroscope?
Answer: The cable line is equivalent to a capacitor. After the power failure, the line still has residual charge, and there is still a potential difference to the ground. If the power is turned off immediately, the electroscope will show that there is power on the line. Therefore, it must be fully discharged, and the grounding wire can be installed after the power is checked.
15. What is internal overvoltage?
Answer: The internal overvoltage is a transition from a stable state to another stable state due to sudden changes in the state of the system due to operation, accident or other reasons. In this process, there may be dangerous overvoltages to the system. . These overvoltages are caused by the oscillation and accumulation of electromagnetic energy in the system, so it is called internal overvoltage.
16. What is the role of the upper pressure equalizing ring of the 220kV valve type arrester?
Answer: After installing the equalizing ring, the voltage distribution of the arrester is even.
17. What is protection and zero? What are the advantages?
Answer: Protecting the zero is the way in which the metal part of the device is not charged under normal conditions, and the wire is directly connected to the system. Take the protection and zero connection method to ensure personal safety and prevent electric shock accidents.
18. What is the role of high voltage circuit breakers ?
Answer: The high-voltage circuit breaker can not only cut off and turn on the no-load current and load current in the high-voltage circuit under normal conditions, but also cooperate with the protection device and the automatic device in the event of a system failure to quickly cut off the fault current and prevent the accident from expanding. Ensure the safe operation of the system.
19. What role does the DC system play in the substation?
Answer: The DC system provides a DC power supply for control, signal, relay protection, automatic devices and accident lighting in the substation. It also provides operational power for operation. The availability of the DC system plays a vital role in the safe operation of the substation and is the guarantee for the safe operation of the substation.
20. In order to keep the battery fully charged during normal float charging, what should the terminal voltage of each battery be kept?
A: In order to keep the battery in full charge, each battery connected to the DC bus must be kept at 2.15V when floating.
21. Why should I install a DC insulation monitoring device?
Answer: Long-term operation of one pole grounding in the DC system of the substation is not allowed, because grounding occurs at another location on the same pole, which may cause malfunction of the signal device, relay protection and control circuit. In addition, when there is one pole grounded, if another pole ground occurs again, it will cause a DC short circuit.
22. What is floating charge?
Answer: Float charging is installed in two charging units, one is the main charging unit and the other is the floating charging unit. Float charging is to compensate for the self-discharge loss of the battery, so that the battery pack is often fully charged.
23. What is the role of the wave blocker?
Answer: The wave blocker is an indispensable high-frequency communication component for carrier communication and high-frequency protection. It prevents high-frequency current from leaking to other branches and reduces the loss of high-frequency energy.
24. What are the phenomena when the system oscillates?
A: The phenomenon when the system oscillates is:
(1) The current, voltmeter and power meter pointers in the substation are periodically oscillated. If there is a tie line, the swing of the meter is most obvious.
(2) The closer to the oscillation center of the system, the greater the voltage swing, and the incandescent lamp flickers and becomes very obvious.
25. What is the role of the signal that has not been returned?
A: The card is not returned to the light signal. It is to prevent the omission of the omission of the duty guard during the process of recording the protection action. It should be noted that the signal should be reset in time to avoid repeated actions, so that the two can not be distinguished. .
26, low voltage AC and DC loop can share a cable, why?
A: No, because:
(1) Sharing a cable can reduce the insulation level of the DC system.
(2) If the DC insulation is broken, the DC mixed line may cause a short circuit or a relay protection malfunction.
27. How much megohmmeter should I use to measure the insulation of the secondary circuit? How many megaohms is the insulation standard?
Answer: It is best to use the 1000V megohmmeter for the insulation resistance of the secondary circuit. If there is no 1000V, the 500V megohmmeter can be used. Its insulation standard: no less than 1 megohm in operation, new input, indoor not less than 20 megohms, outdoor not less than 10 megohms.
28. What are the uses of the auxiliary contacts of the oil switch?
Answer: The oil circuit breaker itself has a normally open and normally closed contact change opening and closing position to open the circuit breaker mechanism closing and tripping circuit and the acoustic signal circuit to achieve the purpose of breaking or closing the circuit breaker, and can be correct. An audible signal is emitted to activate the automatic device and the protective latching circuit. When the auxiliary contacts of the circuit breaker are used in the closing and tripping circuits, there should be a delay.
29. What is the role of current transformers?
Answer: The current transformer converts the large current into a small current according to a certain ratio, providing various currents for instrument use and relay protection, and isolating the secondary system from the high voltage. It not only ensures the safety of people and equipment, but also simplifies and standardizes the manufacture of instruments and relays, and improves economic efficiency.
30. What is the operating principle of overcurrent protection?
Answer: When a phase-to-phase short circuit fault occurs in the power grid, the current will suddenly increase and the voltage will drop suddenly. The overcurrent protection is to set the operating current of the current relay according to the line selectivity requirement. When the fault current in the line reaches the action value of the current relay, the current relay acts selectively to cut off the fault line according to the selectivity requirement of the protection device.
31. What kinds of wiring methods are there for current transformers?
Answer: The current transformer is connected by two-phase V-line and two-phase current difference wiring with two current transformers; three-phase Y-connection, three-phase delta connection and zero sequence using three current transformers wiring.
32. How many reactive power sources are there in the power system?
Answer: The reactive power supply in the power system is: 1 synchronous generator; 2 adjustable camera; 3 parallel compensation capacitor; 4 series compensation capacitor; 5 static compensator.
33. What is the working principle of the transformer's oil purifier?
Answer: The running transformer is circulated in the oil purifier due to the temperature difference between the upper oil temperature and the lower oil temperature. The harmful substances in the oil such as: water, free carbon, oxides, etc. are absorbed by the silica gel in the oil purifier with the circulation of the oil, so that the oil is purified and maintains good electrical and chemical properties, and plays a role in the regeneration of the transformer oil.
34. What is the cooling effect of a strong oil air-cooling device with a guided and unguided transformer?
Answer: Most of the oil flow of a transformer equipped with a non-oriented strong oil air-cooling device flows back through the gap between the wall and the winding. A small part of the oil flows into the winding and the core, and the cooling effect is not high. The cooling oil flowing into the oil tank of the guiding oil-cooled transformer through the oil flow guiding partition effectively flows through the iron core and the inside of the winding, thereby improving the cooling effect and reducing the temperature rise of the winding.
35. What is the role of the thermometer? How many measurement methods are there?
Answer: The thermometer is used to measure the temperature of the upper layer of oil inside the fuel tank, and it plays a role in monitoring the normal operation of the power transformer . According to the size of the transformer, the thermometer can be divided into three kinds of temperature measurement methods: mercury thermometer, signal thermometer and resistance thermometer.
36. What is the function of the opening and closing buffer of the high voltage circuit breaker?
A: The function of the opening buffer is to prevent damage to the components of the circuit breaker due to the huge impact force generated by the spring when the energy is released. The function of the closing damper is to prevent the impact force at the time of closing to make the closing too deep and damage the casing.
37, what is the circuit breaker free trip?
Answer: At any time during the closing process of the circuit breaker, if the protection action is connected to the trip circuit, the circuit breaker can be disconnected*, which is called free tripping. The circuit breaker with free tripping can ensure that the circuit breaker can be disconnected quickly when it is short-circuited, so as to avoid expanding the scope of the accident.
38. What are the good arc extinguishing properties of SF6 gas?
A: SF6 gas has the following good performance:
(1) The arc column has high conductivity, the arcing voltage is very low, and the energy of the arc column is small.
(2) When the alternating current crosses zero, the dielectric insulation strength of SF6 gas recovers quickly, about 100 times faster than air, that is, its arc extinguishing ability is 100 times higher than that of air.
(3) The insulation strength of SF6 gas is high.
39. What are the characteristics of vacuum circuit breakers?
Answer: The vacuum circuit breaker has the characteristics that the contact opening distance is small, the arcing time is short, and the contact is slightly burned when the fault current is broken. Therefore, the operating energy required for the vacuum circuit breaker is small and the action is fast. At the same time, it also has the advantages of small size, light weight, small maintenance workload, fireproof, explosion-proof and low operation noise.
40. What is the meaning of synchronous camera synchronization?
A: When the camera is running, the rotating magnetic field of the stator and the rotor rotate in the same direction and at the same speed. This is called synchronization.
41. After the primary side fuse of the voltage transformer is blown, why not use ordinary fuse instead?
Answer: Take the 10kV voltage transformer as an example. The rated current of the primary fuse is 0.5A. Fuses filled with quartz sand have better arc extinguishing performance and larger current interrupting capacity, and have the effect of limiting short-circuit current. Or ordinary fuses can not meet the current capacity requirements.
42. Why should the secondary side of the voltage transformer and current transformer be grounded?
Answer: The secondary side of the voltage transformer and current transformer is grounded. If the primary and secondary side insulation is damaged, the primary side high voltage string is applied to the secondary side, which will threaten the safety of the person and equipment, so the secondary side must be grounded.
43. What is the nameplate of electrical equipment for FKL-10-2×750-6?
Answer: FKL-10-2×750-6 is the nameplate of aluminum cable splitting reactor with rated reactance of 6%, rated voltage of 10kV and rated current of two branches of 750A.
44. What is the role of shunt reactors and series reactors?
Answer: The line shunt reactor can compensate the capacitive charging current of the line, limit the rise of the system voltage and the generation of the operating overvoltage, and ensure the operation of the line. The busbar series reactor can limit the short-circuit current and maintain a high residual voltage of the busbar. The capacitor bank series reactor can limit higher harmonics and reduce reactance.
45. What are the characteristics of the wiring method of single busbar segmentation?
A: Single bus segmentation wiring can reduce the impact range of bus faults. When a section of the busbar is faulty, the segmented circuit breaker automatically trips under the cooperation of the relay protection, and the faulty section is cut off to keep the non-faulty busbars from supplying normal power. For important users, power can be taken from different segments to ensure uninterrupted power supply.
46. ​​What are the disadvantages of double busbar wiring?
A: The double busbar wiring has the following disadvantages:
(1) Wiring and operation are complicated, and misoperation is easy to occur during the switching operation.
(2) There are many busbar disconnectors , and the structure of the power distribution device is also complicated, so the economy is poor.
47. What is the role of the fault recorder?
Answer: The fault recorder is used in the power system. It can automatically and accurately record the changes of various electrical quantities before and after the fault in the event of system failure. Through the analysis and comparison of these electrical quantities, the accidents are analyzed and handled. It is important to judge whether the protection is correct and to improve the safe operation of the power system.
48. Why do the hard busbars need to be equipped with expansion joints?
Answer: The object has thermal expansion and contraction characteristics. The busbar will change its length due to heat during operation. In order to avoid excessive stress and damage to the busbar and supporting insulator due to changes in thermal expansion and contraction, expansion joints should be installed on the hard busbar.
49. What is the compensation degree of the arc suppression coil, what is the residual flow?
Answer: The ratio of the difference between the inductor current and the capacitor current of the arc suppression coil and the capacitance current of the grid is called the compensation degree. After the inductor current of the arc suppression coil compensates for the capacitor current, the residual current flowing through the ground point is called residual current.
50. Does the arc suppression coil have voltage when the system with the neutral point grounded by the arc suppression coil is in normal operation?
Answer: When the system is in normal operation, due to the unbalanced capacitance of the three grounds of the line, there is a certain voltage between the neutral point of the network and the ground. The magnitude of the voltage value is directly related to the imbalance of the capacitor. Under normal conditions, the voltage generated by the neutral point must not exceed 1.5% of the rated phase voltage.
ZGAR PCC
ZGAR electronic cigarette uses high-tech R&D, food grade disposable pod device and high-quality raw material. All package designs are Original IP. Our designer team is from Hong Kong. We have very high requirements for product quality, flavors taste and packaging design. The E-liquid is imported, materials are food grade, and assembly plant is medical-grade dust-free workshops.
From production to packaging, the whole system of tracking, efficient and orderly process, achieving daily efficient output. We pay attention to the details of each process control. The first class dust-free production workshop has passed the GMP food and drug production standard certification, ensuring quality and safety. We choose the products with a traceability system, which can not only effectively track and trace all kinds of data, but also ensure good product quality.
We offer best price, high quality Vape Device, E-Cigarette Vape Pen, Disposable Device Vape,Vape Pen Atomizer, Electronic cigarette to all over the world.
Much Better Vaping Experience!
ZGAR PCC E-Cigarette Vape Pen,ZGAR PCC Device Vape,ZGAR PCC Vape Pen Atomizer,Latest Disposable E-Cigarette OEM vape pen,ZGAR PCC electronic cigarette
Zgar International (M) SDN BHD , https://www.szvape-pen.com