20 Questions And Answers About Common Knowledge In The Electrical Industry, Check For Omissions
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- Time of issue:2021-08-05
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(Summary description) 1. How many kinds of reactive power sources are in the power system?
The reactive power sources in the power system include:
1. Synchronous generator
2. Adjust the camera
3. Parallel compensation capacitor
4. Series compensation capacitor
5. Static compensator
2. What is the purpose of the current transformer?
The current transformer converts the large current into a small current according to a certain proportion, provides the current for the use of various meters and relay protection, and isolates the secondary system from the high voltage. It not only guarantees the safety of people and equipment, but also simplifies and standardizes the manufacture of meters and relays, and improves economic benefits.
3. Why install a set of lightning arresters between the power capacitor and its circuit breaker?
The installation of lightning arrester can prevent the operation overvoltage that may occur during the pulling and closing operation of the power capacitor, and ensure the operation of electrical equipment.
4. What are the wiring methods for current transformers?
There are two current transformers, two-phase V-shaped wiring and two-phase current difference wiring; there are three-phase Y-shaped wiring, three-phase delta wiring and zero sequence wiring that use three current transformers.
5. Why must the secondary side of the voltage transformer and current transformer be grounded?
The secondary side grounding of the voltage transformer and current transformer is a protective grounding. If the primary, secondary, and secondary side insulation is damaged, the primary side high voltage will be connected to the secondary side, which will threaten people and equipment, so the secondary side must be grounded.
6. What is the function of parallel reactor and series reactor?
The line shunt reactor can compensate the capacitive charging current of the line, limit the rise of the system voltage and the generation of operating overvoltage, and ensure the reliable operation of the line.
The busbar series reactor can limit the short-circuit current and maintain a high residual voltage of the busbar. The series reactor of the capacitor bank can limit the higher harmonics and reduce the reactance.
7. What are the characteristics of the single-bus section wiring method?
Single busbar segmented wiring can reduce the influence range of busbar faults and improve the reliability of power supply. When a section of the bus has a fault, the section circuit breaker will automatically trip under the cooperation of the relay protection to remove the fault, so that the non-faulty bus maintains normal power supply. For important users, power can be obtained from different sections to ensure uninterrupted power supply.
8. What are the disadvantages of double bus wiring?
The double bus has the following disadvantages:
1. Wiring and operation are relatively complicated, and misoperation is prone to occur during switching operation
2. There are many bus isolation switches, and the structure of the power distribution device is more complicated, so the economy is poor
9. What is the compensation degree of the arc suppression coil and what is the residual current?
The ratio of the difference between the inductance current and the capacitance current of the arc suppression coil and the capacitance current of the power grid is called the compensation degree. After the inductance current of the arc suppression coil compensates for the capacitive current, the residual current flowing through the grounding point is called residual current.
10. When the system whose neutral point is grounded through the arc suppression coil is operating normally, does the arc suppression coil carry voltage?
When the system is operating normally, due to the unbalanced three-phase ground capacitance of the line, there is a certain voltage between the neutral point of the network and the ground, and the magnitude of the voltage value is directly related to the unbalanced capacitance. Under normal conditions, the voltage generated by the neutral point cannot exceed 1.5% of the rated phase voltage.
11. Why does the battery self-discharge?
The main reason for the self-discharge of the battery is that the pole plates contain impurities, which form a local small battery, and the two poles of the small battery form a short circuit, which causes the battery to self-discharge. In addition, due to the difference in the density of the battery electrolyte from top to bottom, the electromotive force on the top and bottom of the electrode plate is uneven, which will also cause self-discharge of the battery.
12. Why should the battery be charged and discharged regularly?
Periodic charging and discharging is also called checking charging and discharging. It is to perform a larger charge and discharge reaction on the battery operating on floating charge after a certain period of time to check t
电气行业常用知识问答20项，查漏补缺
电气行业常用知识问答20项，查漏补缺
20 Questions And Answers About Common Knowledge In The Electrical Industry, Check For Omissions
(Summary description) 1. How many kinds of reactive power sources are in the power system?
The reactive power sources in the power system include:
1. Synchronous generator
2. Adjust the camera
3. Parallel compensation capacitor
4. Series compensation capacitor
5. Static compensator
2. What is the purpose of the current transformer?
The current transformer converts the large current into a small current according to a certain proportion, provides the current for the use of various meters and relay protection, and isolates the secondary system from the high voltage. It not only guarantees the safety of people and equipment, but also simplifies and standardizes the manufacture of meters and relays, and improves economic benefits.
3. Why install a set of lightning arresters between the power capacitor and its circuit breaker?
The installation of lightning arrester can prevent the operation overvoltage that may occur during the pulling and closing operation of the power capacitor, and ensure the operation of electrical equipment.
4. What are the wiring methods for current transformers?
There are two current transformers, two-phase V-shaped wiring and two-phase current difference wiring; there are three-phase Y-shaped wiring, three-phase delta wiring and zero sequence wiring that use three current transformers.
5. Why must the secondary side of the voltage transformer and current transformer be grounded?
The secondary side grounding of the voltage transformer and current transformer is a protective grounding. If the primary, secondary, and secondary side insulation is damaged, the primary side high voltage will be connected to the secondary side, which will threaten people and equipment, so the secondary side must be grounded.
6. What is the function of parallel reactor and series reactor?
The line shunt reactor can compensate the capacitive charging current of the line, limit the rise of the system voltage and the generation of operating overvoltage, and ensure the reliable operation of the line.
The busbar series reactor can limit the short-circuit current and maintain a high residual voltage of the busbar. The series reactor of the capacitor bank can limit the higher harmonics and reduce the reactance.
7. What are the characteristics of the single-bus section wiring method?
Single busbar segmented wiring can reduce the influence range of busbar faults and improve the reliability of power supply. When a section of the bus has a fault, the section circuit breaker will automatically trip under the cooperation of the relay protection to remove the fault, so that the non-faulty bus maintains normal power supply. For important users, power can be obtained from different sections to ensure uninterrupted power supply.
8. What are the disadvantages of double bus wiring?
The double bus has the following disadvantages:
1. Wiring and operation are relatively complicated, and misoperation is prone to occur during switching operation
2. There are many bus isolation switches, and the structure of the power distribution device is more complicated, so the economy is poor
9. What is the compensation degree of the arc suppression coil and what is the residual current?
The ratio of the difference between the inductance current and the capacitance current of the arc suppression coil and the capacitance current of the power grid is called the compensation degree. After the inductance current of the arc suppression coil compensates for the capacitive current, the residual current flowing through the grounding point is called residual current.
10. When the system whose neutral point is grounded through the arc suppression coil is operating normally, does the arc suppression coil carry voltage?
When the system is operating normally, due to the unbalanced three-phase ground capacitance of the line, there is a certain voltage between the neutral point of the network and the ground, and the magnitude of the voltage value is directly related to the unbalanced capacitance. Under normal conditions, the voltage generated by the neutral point cannot exceed 1.5% of the rated phase voltage.
11. Why does the battery self-discharge?
The main reason for the self-discharge of the battery is that the pole plates contain impurities, which form a local small battery, and the two poles of the small battery form a short circuit, which causes the battery to self-discharge. In addition, due to the difference in the density of the battery electrolyte from top to bottom, the electromotive force on the top and bottom of the electrode plate is uneven, which will also cause self-discharge of the battery.
12. Why should the battery be charged and discharged regularly?
Periodic charging and discharging is also called checking charging and discharging. It is to perform a larger charge and discharge reaction on the battery operating on floating charge after a certain period of time to check t
- Categories:Industry News
- Author:
- Origin:
- Time of issue:2021-08-05
- Views:0
1. How many kinds of reactive power sources are in the power system?
The reactive power sources in the power system include:
1. Synchronous generator
2. Adjust the camera
3. Parallel compensation capacitor
4. Series compensation capacitor
5. Static compensator
2. What is the purpose of the current transformer?
The current transformer converts the large current into a small current according to a certain proportion, provides the current for the use of various meters and relay protection, and isolates the secondary system from the high voltage. It not only guarantees the safety of people and equipment, but also simplifies and standardizes the manufacture of meters and relays, and improves economic benefits.
3. Why install a set of lightning arresters between the power capacitor and its circuit breaker?
The installation of lightning arrester can prevent the operation overvoltage that may occur during the pulling and closing operation of the power capacitor, and ensure the operation of electrical equipment.
4. What are the wiring methods for current transformers?
There are two current transformers, two-phase V-shaped wiring and two-phase current difference wiring; there are three-phase Y-shaped wiring, three-phase delta wiring and zero sequence wiring that use three current transformers.
5. Why must the secondary side of the voltage transformer and current transformer be grounded?
The secondary side grounding of the voltage transformer and current transformer is a protective grounding. If the primary, secondary, and secondary side insulation is damaged, the primary side high voltage will be connected to the secondary side, which will threaten people and equipment, so the secondary side must be grounded.
6. What is the function of parallel reactor and series reactor?
The line shunt reactor can compensate the capacitive charging current of the line, limit the rise of the system voltage and the generation of operating overvoltage, and ensure the reliable operation of the line.
The busbar series reactor can limit the short-circuit current and maintain a high residual voltage of the busbar. The series reactor of the capacitor bank can limit the higher harmonics and reduce the reactance.
7. What are the characteristics of the single-bus section wiring method?
Single busbar segmented wiring can reduce the influence range of busbar faults and improve the reliability of power supply. When a section of the bus has a fault, the section circuit breaker will automatically trip under the cooperation of the relay protection to remove the fault, so that the non-faulty bus maintains normal power supply. For important users, power can be obtained from different sections to ensure uninterrupted power supply.
8. What are the disadvantages of double bus wiring?
The double bus has the following disadvantages:
1. Wiring and operation are relatively complicated, and misoperation is prone to occur during switching operation
2. There are many bus isolation switches, and the structure of the power distribution device is more complicated, so the economy is poor
9. What is the compensation degree of the arc suppression coil and what is the residual current?
The ratio of the difference between the inductance current and the capacitance current of the arc suppression coil and the capacitance current of the power grid is called the compensation degree. After the inductance current of the arc suppression coil compensates for the capacitive current, the residual current flowing through the grounding point is called residual current.
10. When the system whose neutral point is grounded through the arc suppression coil is operating normally, does the arc suppression coil carry voltage?
When the system is operating normally, due to the unbalanced three-phase ground capacitance of the line, there is a certain voltage between the neutral point of the network and the ground, and the magnitude of the voltage value is directly related to the unbalanced capacitance. Under normal conditions, the voltage generated by the neutral point cannot exceed 1.5% of the rated phase voltage.
11. Why does the battery self-discharge?
The main reason for the self-discharge of the battery is that the pole plates contain impurities, which form a local small battery, and the two poles of the small battery form a short circuit, which causes the battery to self-discharge. In addition, due to the difference in the density of the battery electrolyte from top to bottom, the electromotive force on the top and bottom of the electrode plate is uneven, which will also cause self-discharge of the battery.
12. Why should the battery be charged and discharged regularly?
Periodic charging and discharging is also called checking charging and discharging. It is to perform a larger charge and discharge reaction on the battery operating on floating charge after a certain period of time to check the capacity of the battery, and to find the aging battery and maintain it in time. To ensure the normal operation of the battery, regular charging and discharging are generally not less than once a year.
13. What is the unbalanced current of the transformer? What are the requirements?
The unbalanced current of the transformer refers to the current difference between the windings of the three-phase transformer. In a three-phase three-wire transformer, the unbalance of each phase load must not exceed 20%. In a three-phase four-wire transformer, the neutral current caused by the unbalanced current must not exceed 25% of the rated current of the low-voltage winding. If the above regulations are not met, the load should be adjusted.
14. Which part of the winding is hot during normal operation of the transformer?
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