12kv/24kv/33kv Box-Type Transformer Package Substation
Package Substation Detail Description
SHME Custom-designed and manufactured to meet the customer's needs, SHME Box Type Substation have a modular design, providing flexibility to meet a wide range of applications in different sectors.
If you are looking for a complete package substation solution, SHME team could be just what you need.
Overview:
The box-type substation (hereinafter referred to as the device) is suitable for outdoor power distribution devices with a primary side AC rated voltage of 3.6~40.5kV, a maximum transformer capacity of 1600kVA and a frequency of 50Hz. The device is formed by connecting a high-voltage switchgear, a transformer and a low-voltage switchgear.
The device can be widely used in municipal engineering, residential quarters, industrial and mining enterprises, road lighting and other places, and is a recommended product for urban and suburban power grid construction.
Model description:
SPSO - ( ) / ( )
Meaning: S-SHME
P-Package
O-Outside
First()-High Voltage
Second()-Transformer Capacity
Features:
The box-type substation has the characteristics of compact structure, strong complete set, safe and reliable operation, convenient maintenance and beautiful appearance.
The box-type substation has a small footprint and flexible installation. The box-type substation can be deeply built in the load center, thereby improving the quality of power supply, reducing power loss, and achieving the purpose of high-quality, safe, energy-saving and reliable power supply.
It can realize factory-to-order production, with short manufacturing cycle and quick installation, which can greatly shorten the user's power supply time, and has obvious economic advantages.
Special box transformers can be designed according to user needs, such as street lamp control box transformers, wind power dedicated cabinet transformers, oil well dedicated cabinet transformers, etc. Through special materials and special structure design, it can meet the requirements of electromagnetic compatibility in special places.
In order to meet the strict requirements of municipal engineering for power supply reliability, our company adopts insulated and shielded wiring, sealed flood-proof design, so as to ensure reliable equipment operation and personal safety, supporting unit-controlled FTU (distribution network monitoring terminal), which constitutes a one-step process. The distribution automation intelligent box-type substation can realize the function of distribution automation (fault identification and isolation).
In order to reduce the occurrence of transformer oil infiltration into the underground polluting environment due to transformer leakage failure, our company has launched a caisson compact box-type substation. The base of the device has good rigidity and high strength, and is a very good basic component. It can fix components such as enclosures, partitions, door frames and electrical equipment in the box. Concealed hoisting shafts are installed on the side beams on both sides. The lower part is a fully enclosed body, which has the characteristics of protecting the environment.
There are 4 ways for cable entry and exit: overhead entry and exit, Cable in and out at bottom, cable overhead entry and cable out at bottom, overhead entry and cable overhead out. Flexible selection of a variety of incoming and outgoing lines to meet the user's construction site restrictions on cable corridors.
If the device is used for temporary construction electricity projects, this product has the characteristics of convenient transportation, installation and quick disassembly. According to the special needs of users, the device can also be installed on the car or added with moving wheels, which is more convenient and fast to transport.
The shell of the device can be made of color steel sandwich panel, steel plate or stainless steel, glass fiber cement and other materials according to the needs of the user. The shape and color of the device are more coordinated with the surrounding environment and increase the color of human landscape. If the user has special requirements, our company can also make Shell painted box change. The casing of the box changer is made of fire-resistant and flame-retardant materials, and all materials have excellent weather resistance and anti-corrosion ability after special processing.
The top cover of the box changer is designed as a "herringbone"-shaped double-sided slope structure, which has a good effect of preventing rain and snow. The internal ventilation, heating and condensation systems are well designed to ensure reliable operation of the product under harsh environmental conditions.
The high-voltage and low-voltage switchgears in the device are highly complete, and the transformers and switchgears are all pre-installed and dismountable structures. Transformers and switch cabinets can be hoisted as a whole, which is very beneficial to the replacement and overhaul of components. The "five-proof" locking of switchgear is reasonable and reliable, which is of great significance to improve the safety of equipment and protect the safety of operators.
The combination of natural ventilation and forced ventilation is adopted to ensure the normal use of components and transformers in the device. It can also be equipped with dual-temperature air conditioners according to the harshness of the climate at the location of use to meet the strict temperature requirements of automatic control equipment such as inverters and soft starters in the device.
The high-voltage part is composed of XGN-12 ring network cabinets to form a primary power supply system. The power supply mode is flexible. It can be arranged into various power supply methods such as terminal power supply, ring network power supply, and dual power supply according to needs. High-voltage metering units can also be installed to meet metering needs. . The main high-voltage components can be selected from permanent magnet vacuum circuit breakers, vacuum circuit breakers, load switches, SF6 switches and other components according to the design scheme. All components can be selected from international brands or Chinese products.
The transformers in the device can be selected from SC dry-type transformers or S11-M fully sealed oil-immersed power transformers. The device can also be configured with reactive power compensation unit, meter installation unit, power data acquisition terminal installation unit, street lamp lighting unit and other configurations according to user requirements.
Use environmental conditions:
1) Installation location: outdoor
2) Altitude: ≤1500 meters
3) Ambient temperature: maximum: +50ºC, minimum -40ºC
4) Outdoor wind speed does not exceed 35m/s
5) Ambient relative humidity: ≤90% (+25ºC)
6) Earthquake cracking degree: 8 degrees
7) The installation site is free from fire, explosion hazard, chemical corrosion and vibration
Standards and Specifications:
DL/T537 for Guidelines for selection of high/low voltage pre-packaged box-type substations
GB4028 for Enclosure Protection Level (IP Code)
GB/T17467 for High Voltage/Low Voltage Prefabricated Substation
IEC 62271-1 as common specifications for high voltage switchgears
IEC 62271-200 for AC metal-enclosed switchgears
IEC 62271-201 for insulation-enclosed switchgears
IEC 62271-202 high voltage, low voltage prefabricated substation
IEC 60076 for power transformers
IEC 61439 for low voltage switchgears
All versions of standards and specifications may be revised, and suppliers should seek the possibility of adopting the latest version of specifications and standards.
Main technical performance parameters:
| Item |
unit |
parameter |
High
voltage
unit |
Rated Frequence |
Hz |
50 |
| Rated voltage |
kV |
6 /10/35 |
| Maximum working voltage |
kV |
7.2/12/40.5 |
| Power Frequency Withstand Voltage Ground and Phase/Isolation Breaks |
kV |
32/36. 42/48. 95/99 |
| Lightning impulse voltage to earth and phase-to-phase/isolation fractures |
kV |
60/70. 75/85. 185/189 |
| Rated current |
A |
630/1250. 630/1250. 630 |
| Rated short-time withstand current |
kA |
12.5, 12.5, 12.5 |
| Rated peak withstand current |
kA |
25. 25. 25 |
Low
voltage
unit |
Rated voltage |
kV |
0.4 |
| Main circuit rated current |
A |
630-3150 |
| Rated short-time withstand current |
kA |
15/30/50 |
| Rated peak withstand current |
kA |
30 |
| Branch current |
A |
6-2500 |
| Compensation capacity |
kVar |
≥30%×Sn |
Trans
former
unit |
Rated Capacity |
kVA |
30-1600 |
| Impedance voltage |
% |
4 |
4.5 |
6 |
| Tap range |
|
±5% |
±2×2.5% |
| link type |
|
Y yn0 |
D yn11 |
| |
|
|
|
|
|
|
Box-type substation shell technical requirements:
- The shell of the box-type substation can choose color steel sandwich panel, steel plate (stainless steel), environmental protection non-metallic landscape shell (glass fiber cement shell) box and other forms of boxes according to user needs. The thickness of the insulation layer of the box is not less than 50mm, the layout of the internal equipment is compact, and the appearance is coordinated with the surrounding environment. The box body has sufficient mechanical strength and will not deform during transportation and installation;
a. Color steel sandwich panel shell features
Color steel sandwich panel is currently the most widely used new type of building wall material. Our company adopts color-coated panels produced by Baosteel or Wuhan Iron and Steel. It is made of polystyrene EPS, polyurethane PU and other materials of fuel. The color steel sandwich panel has the advantages of light weight, high strength, heavy bearing capacity, firm coating adhesion, beautiful color, quick installation, and durability. It is a safe and reliable green product vigorously promoted by the country.
b. Features of steel shell
The shell of the device is made of high-quality cold-rolled steel plate with a thickness of 50mm, of which the thickness of the outer steel plate is δ: 2.0, and the inner steel plate is galvanized steel with δ: 1.0. The intermediate filling material is flame retardant polystyrene board or rock wool board. After the steel plate is treated by degreasing, rust removal, pickling and phosphating, the surface is treated by electrostatic spraying, and then placed in the drying room for baking to ensure that the outer topcoat is combined with the steel plate and cured. The box-type steel plate shell has strong corrosion resistance.
According to the needs of users, the steel plate shell can be made into corrugated shape, corrugated spray-painted color strip shape, or the outer surface of the steel plate can be hung with pine boards that have been treated with special processes such as deworming, heating and drying, and dipping. , villas and other places.
c. Environmentally friendly non-metallic landscape shell (glass fiber cement shell)
The glass fiber cement shell is a new product developed and trial-manufactured by our company by absorbing the advantages of similar products at home and abroad, and combining with the characteristics of Xinjiang's use environment. The wall materials are made of sand and gravel, cement, ceramsite, and glass fibers in a scientific ratio, and built-in staggered lapped steel mesh. Has the following characteristics:
1. Strong mechanical bending, impact and tensile strength;
2. Strong anti-explosion, anti-radiation and thermal insulation capabilities;
3. Excellent anti-freezing, anti-cracking and anti-corrosion properties;
4. Excellent moisture-proof and flame-retardant properties, no condensation will occur under sudden cooling and temperature changes in the heat-accumulating environment;
5. "All-weather" use performance, which can be coordinated with the surrounding environment;
6. The shape structure and decorative color are optional;
7. The shell has strong weather resistance, and the service life can reach 50 years;
2) All doors of the box-type substation are opened outwards, and sealing strips are arranged around the doors. The box-type substation has measures such as wind and sand, rain, rust, and small animals;
3) The top cover of the box changer is designed as a "herringbone"-shaped double-sided slope structure, with a slope of ≮3°, the water on the top can quickly fall, and the function of preventing rain and snow is strong;
4) The metal casing of the box-type substation has a good grounding;
5) The box transformer room, high and low voltage rooms are equipped with lights for operation and maintenance personnel;
6) The transformer room is protected by a special protective net and hangs warning signs. The transformer room is provided with an electrical blocking circuit or an electric bell alarm circuit to prevent personnel from entering the live interval by mistake.
Hoisting and Transportation
Hoisting
1) Generally, box-type substations should not be transported by forklifts, and must be hoisted into place with a suitable crane;
2) Lifting should be carried out in accordance with relevant lifting safety regulations, and appropriate lifting equipment should be selected according to the nominal weight of the device nameplate;
3) When the device is hoisted, it should be ensured that the included angle between the hoisting wire ropes is not greater than 60°, and the box should be hoisted smoothly;
4) When lifting from the bottom, a special sling should be used to avoid damaging the top cover, see figure
Transportation
1) The inclination of the device during transportation should not be greater than 30°;
2) For components that are vulnerable to vibration, such as electric energy meters, relays, etc., they can be removed before long-distance transportation, and they are packaged separately in shock-proof packaging, and then restored after transportation;
3) When the product is transported, it should be placed in its normal position, and the base of the device or the packaging chassis and the means of transport must be firmly bound, and the product is not allowed to move or shake significantly during transportation. Except for the base, hook and top lifting ring, it is not allowed to pull other parts of the device.
Inspection and acceptance
1) Check whether the product is consistent with the order contract, such as product model, rated capacity, circuit scheme, etc.;
2) Check whether the factory documents are complete;
3) Check whether the quantity of each item on the packing list is consistent with the actual item;
4) Check the appearance for bumps, deformations, internal electrical components and connections for damage, fall off and looseness.
Installation and commissioning
1) Before installation, the foundation, grounding system, cable trench, and incoming and outgoing cables and protection pipes should be pre-buried. The installation site of the device should be selected:
a. Places that are not low-lying and prone to water accumulation;
b. Well-ventilated place;
c. Try to avoid places with existing underground public facilities;
2) The installation foundation of the device can be constructed with reference to the basic scheme recommended by the factory, or the foundation can be designed by itself, but the ventilation area of the device should be ensured not less than the ventilation area of the original foundation drawing. For products designed according to user requirements, our company provides in the factory documents. . The foundation should take measures to prevent small animals from entering the bottom of the device and causing harm to the normal operation of the product;
3) The grounding system shall be constructed by the user according to the geological conditions of the installation site and relevant regulations. Regardless of the grounding method, the grounding resistance is required to be no greater than 4Ω;
4) Pre-dug cable trenches, pre-buried cables and protection pipes. The inner diameter of the protection tube is not less than 1.5 times the outer diameter of the cable, and the bending radius of the cable should be greater than 10 times the outer diameter of the cable;
5) During installation, hoist the box transformer to the base according to the provisions of "Hoisting", straighten it and lay it flat, fasten the anchor bolts, connect the high and low voltage cables as required, and firmly connect the ground end of the grounding system to the ground end of the box transformer. Connection, cable shield and armor should also be grounded.
Inspection before commissioning
After installation, the following items should be checked before power transmission and operation:
1) Whether the surface of each component inside the product is clean, dry and free of foreign matter;
2) Whether the movable components such as operating mechanism and switch are flexible, reliable and accurate. Products equipped with temperature display, temperature control, fan, condensation control and other devices should also be checked according to the electrical performance requirements and the installation and use instructions of these products;
3) Whether all the main circuit and grounding circuit connections are tightened. Whether the auxiliary circuit contacts meet the requirements of the electrical schematic diagram;
4) Whether the mounting screws of electrical components and equipment (including transformers and high and low voltage switchgear) are fastened;
5) Whether the electrical setting values of the auxiliary circuit and the control circuit are correct, and whether the transformation ratio of the instrument and the transformer and the wiring polarity are correct. All electrical components are abnormal. If the problem is found in the inspection, it should be solved immediately. If the user cannot solve it, please notify the manufacturer immediately.
Pre-run test
1) The following tests should be performed before the transformer is operated;
a. Test of winding DC resistance;
b. Iron core grounding inspection, insulation inspection of through-core screw;
c. Insulation resistance test: under dry environment conditions, the insulation resistance of high voltage and ground is not less than 300MΩ, and the insulation resistance of low voltage and ground is not less than 100MΩ; under humid environment conditions, the insulation resistance per 1000V rated voltage is not less than 2MΩ;
d. Power frequency withstand voltage test: the test voltage is 85% of the transformer's factory test voltage, and the time is determined with reference to the factory test report value;
When the high-voltage switchgear and the transformer are connected by insulation, the power frequency withstand voltage test of the transformer shall be carried out together with the conductors; if the high-voltage cable connection is used, the connection between the cable and the transformer and the high-voltage switchgear shall be disconnected during the test, and the cables shall be tested separately. Frequency withstand voltage test, the test requirements refer to the factory test report of the device;
2) The power frequency withstand voltage test should be carried out before the high-voltage switchgear is operated. The test voltage is 80% of the factory test voltage of the high-voltage switchgear, and the test time is 1min;
3) Before the operation of the low-voltage switchgear, a 500V shaker should be used to measure the insulation resistance, and the resistance value should not be less than 0.5MΩ;
* * *Note: If power is supplied in high humidity weather, the electrical appliances inside the product must be checked and dried before power supply. And after passing the "pre-operation test" steps, the power can be sent.
Put into operation
If the above items all meet the requirements, the power will be sent and put into operation according to the following steps;
a. Disconnect all high and low voltage switches, close the switch cabinet door and the transformer room door;
* * *Note: The grounding switch (if any) on the high-voltage side of the device must be disconnected, otherwise closing the previous level switch will cause a three-phase-to-ground short circuit;
b. Close the front-stage switch of the high-voltage incoming line of the device;
c. Turn on the high-voltage main switch, observe whether the indication of the instrument is normal, and check whether the power-on condition of the transformer is normal, otherwise it should be checked with power off;
d. Turn on the low-voltage main switch and the branch switch, turn on the load and the main switch for capacitor compensation, and check whether each indicator light and meter are normal.
Power outage operation steps
a. Sub-capacitor compensation main switch, branch circuit switch, disconnect the load, sub-voltage main switch, low-voltage power failure is completed;
b. Sub-box to high-voltage switch;
c. The sub-box becomes the first-level switch.
Maintenance
1) The electrical equipment (including switch cabinets, transformers, etc.) inside the device should be regularly inspected and maintained according to the requirements of their respective installation and operation instructions and relevant regulations;
2) The device should avoid the strong impact of hard objects, so as not to damage the outer protective layer and affect the anti-corrosion effect;
3) The installation of high and low voltage switchgear can open the door or remove the panel for general maintenance from the front. If overhauling or replacing the main equipment, just remove the fixing nut of the top cover of the device, lift the top cover, and then lift out the transformer or The switchgear is overhauled or replaced.
Operation, testing and overhaul of capacitors (if equipped)
A. Operation of the capacitor bank
In order to ensure the safe operation of the capacitor bank, the operation of the capacitor bank should comply with the following items:
1. Under normal circumstances, when the box-type substation is powered off, the capacitor bank isolating switch (or fuse type isolating switch) should be opened first, then the feeder circuit breakers, and finally the incoming line circuit breaker. When power transmission is resumed, the incoming circuit breaker should be closed first, then each feeder circuit breaker, and finally the isolation switch (or fuse type isolation switch) of the capacitor bank. In the event of an accident, the capacitor bank isolating switch (or fuse type isolating switch) must be pulled open after the entire station has no electricity.
This is because when the busbar of the box-type substation is unloaded, the busbar voltage may be high, which may exceed the allowable voltage of the capacitor, which is not good for the insulation of the capacitor. In addition, the capacitor bank may resonate with the no-load transformer and cause the overcurrent protection to operate. Therefore, the situation of no-load airdrop capacitors should be avoided as much as possible.
2. After the capacitor bank protection circuit breaker or fuse fuse is blown, it is not allowed to replace the fuse for power transmission until the cause is identified.
This is because capacitor bank protection circuit breakers or blown fuse fuses can be caused by capacitor failure. Only after checking that the circuit breaker is opened or the fuse is blown due to external reasons, can it be re-closed and tested.
3. The capacitor bank is prohibited from closing with electric charge. The capacitor bank can only be re-closed after 3 minutes after the capacitor bank is cut off.
In an AC circuit, if the capacitor is closed with a charge, the capacitor may be subjected to a peak value of about 2 times the rated voltage, or even higher. This is detrimental to capacitors, and also causes a large inrush current to open circuit breakers or blow fuses. Therefore, the capacitor bank must be discharged immediately after each cut off, and can be closed again after the charge disappears. Therefore, each re-closing of the capacitor bank must be carried out after the capacitor bank is disconnected for 3 minutes.
B. Inspection and inspection of capacitor banks in operation
Routine inspections and regular power outage inspections should be carried out for capacitor banks in operation. After the circuit breaker is opened, the fuse is blown, etc., additional special inspections should be carried out.
1. The daily patrol inspection of the capacitor bank should be carried out by qualified operating personnel on duty. The patrol inspection in summer should be arranged when the room temperature is the highest, and other times can be carried out when the system voltage is the highest. If it is difficult to check without power failure, the power can be cut off for a short time for better inspection. When doing this kind of inspection, you should mainly pay attention to observe whether the capacitor shell is swollen, whether there are traces of oil leakage, whether there is abnormal sound and sparks, and whether the melting of the warm wax chip; check whether the fuse is blown; observe the voltmeter, ammeter, The value of the thermometer shall be recorded in the operation record book, and other defects found shall also be recorded.
In the above patrol inspection, if the capacitor bank needs to be powered off, in addition to the automatic discharge of the capacitor bank, manual discharge should also be performed, and a temporary grounding wire should be suspended. Otherwise, the operating duty personnel cannot touch the capacitor.
2. Regular power failure inspection of capacitor banks should generally be carried out once a month. In addition to the daily inspection items, the inspection contents should also check the tightness and contact of the bolt fastening points, check the integrity of the discharge circuit, check the dust in the ventilation duct, and clean the capacitor shell, insulator and bracket. , Check the protective grounding wire of the capacitor shell, check the action of the relay protection device of the capacitor bank, and check the circuit breaker and feeder of the capacitor bank.
3. When the circuit breaker is opened or the protective fuse is blown in the capacitor bank, special inspection should be carried out immediately. Special inspections should also be carried out for outdoor capacitor banks, in case of thunder, wind, rain, snow and other bad weather. In addition to the above items, the special inspection inspection items should be tested on the capacitor if necessary, and the closing and power transmission are prohibited until the cause of the fault cannot be found. .
C Abnormal phenomenon and troubleshooting in capacitor operation
1. Oil leakage
Due to improper handling methods or installation methods, cracks are formed in the contacts of the lead-out terminals, or excessive force is applied to tighten the nuts during wiring, resulting in damage to the contacts of the lead-out terminals and some defects in the product manufacturing process, which may cause capacitors. Oil leakage occurs. At the same time, because the temperature changes drastically after the capacitor is put into operation, the internal pressure increases, which will make the leakage of oil more serious. In addition, after long-term operation, the paint layer of the capacitor shell may be peeled off, and the iron sheet may be corroded, which is also a cause of oil leakage of the capacitor during operation.
The consequence of the leakage of oil from the capacitor is that the impregnating agent is reduced, and the upper part of the component is easily damaged by moisture and breakdown, so the capacitor must be repaired in time.
2. Shell expansion
Because the internal medium of the capacitor is dissociated under the action of voltage, the medium is decomposed and gas is released, or the gas is released from the medium due to the breakdown of some components, pole-to-shell discharge, etc. These gases will cause an increase in pressure in the sealed enclosure, thereby causing the enclosure to expand. Therefore, capacitor case swelling is a symptom of capacitor failure or pre-failure. If the capacitor casing is found to expand during operation, measures should be taken in time. If the expansion is serious, the use should be stopped immediately to avoid the expansion of the accident.
3. Explosion of capacitors
When the inside of the capacitor breaks down between poles or between poles to the shell, the capacitor bank running in parallel with it will discharge it. At this time, the capacitor may burst due to the great energy. Since low-voltage capacitors are generally equipped with component protection fuses, such accidents mostly occur in high-voltage capacitor banks without internal component protection. The consequences of capacitor blasting may endanger other electrical equipment and even cause a fire in the capacitor room (cabinet). In order to prevent the explosion accident of the capacitor, in addition to the requirement to strengthen the patrol inspection during operation, the most important thing is to install the protection device for the internal components of the capacitor, so that the capacitor can be removed from the power grid in time before the explosion accident occurs.
4. The temperature is too high
Poor ventilation conditions due to unreasonable design and installation of the capacitor room (cabinet), long-term overvoltage operation of the capacitor bank, and overcurrent of the capacitor due to the influence of the high-order harmonic current caused by the nearby rectifier components, etc., can cause the capacitor to exceed the allowable limit. temperature rise. In addition, due to the dielectric aging of the capacitor after long-term operation, the dielectric loss (tgδ) continues to increase, which may also cause the capacitor temperature to rise too high. The long-term operation of the capacitor at a temperature exceeding the specified temperature will seriously affect its service life, and will cause damage to the capacitor due to accidents such as insulation breakdown. Therefore, its ambient temperature should be strictly monitored and controlled during operation, and measures should be taken so that it does not exceed the allowable temperature rise. If the temperature rise still exceeds the specified allowable temperature after taking measures, the capacitor bank should be stopped.
5. Porcelain insulation surface flashover
Due to the lack of cleaning and maintenance of capacitors in operation, the porcelain insulating surface of the capacitor may cause discharge due to contamination. In areas with severe pollution, especially in bad weather conditions (such as wind, rain, snow, thunder, etc.), or in the case of various internal and external overvoltages and system resonance, it can cause a flashover accident on the surface of porcelain insulation. , causing capacitor damage and switch tripping. Therefore, the capacitor bank in operation should be regularly cleaned and inspected, and other appropriate measures should be taken in areas with severe pollution.
6. Abnormal noise
The capacitor should not make a special noise during operation. If there is a "zizi" sound or a "gugu" sound during operation, it means that there is partial discharge externally or internally. The "cuckoo" sound is a harbinger of the breakdown of the capacitor's internal insulation, so it is necessary to stop the operation immediately and find the faulty capacitor.
When dealing with the faulty capacitor, the switch of the capacitor and the upper and lower knife switches should be opened first. If a fuse is used for control and protection, its fuse tube should be removed. At this time, although the capacitor bank has been self-discharged through the discharge resistor, there is still some residual charge, so manual discharge must be performed. When discharging, firstly connect the grounding end of the temporary grounding wire to the grounding grid, and then use the grounding rod to discharge the capacitor several times until there is no spark or discharge sound. Finally, connect the ground wire firmly to the capacitor bus bar.
Special attention should also be paid to the faulty capacitor itself, which may also have residual charge between its two poles. This is because the faulty capacitor may be an internal disconnection or a blown fuse, or the lead wire may be in poor contact, so that its residual charge will not be discharged during automatic discharge or manual discharge. Therefore, before the operation or maintenance personnel touch the faulty capacitor, they should also wear insulating gloves, short-circuit the two poles of the faulty capacitor with a short-circuit wire to discharge it, and then start disassembly. In addition, capacitors wired in series should also be discharged individually. In a word, because the two poles of the capacitor have the characteristics of residual charge, it is necessary to discharge the charge from all aspects, otherwise electric shock accidents are likely to occur.
D. Precautions for the use of self-healing power capacitors:
1. When multiple capacitors are used together, the spacing should be kept more than 30mm to facilitate heat dissipation.
2. The wire connecting the capacitor should be able to withstand more than 1.3 times the rated current of the capacitor.
3. The capacitor terminals and wires should be well connected, especially the terminal nuts must be pressed tightly to avoid heat damage to the insulation of the capacitor.
4. Due to the existence of power grid harmonics, in order to ensure that the working current (steady state) of the capacitor does not exceed 1.3 times the rated value, thermal relay current limiting protection is required.
5. In order to suppress the inrush current (transient) of the capacitor input, an anti-inrush current reactor or a capacitor special contactor must be used.
6. In order to use the capacitor under normal voltage, the steady-state overvoltage protection must be used (generally, the automatic reactive power compensation instrument has this function).
7. In order to avoid damage to the capacitor caused by transient overvoltage, lightning arresters or varistors are used for protection. After the capacitor is switched and reconnected to the network, there should be a certain time delay to ensure that the residual voltage of the capacitor is not greater than 50V.
Full range high voltage current limiting fuses for transformer protection:
| Transformer capacity kVA |
12kV fuse |
| Type |
Rated current A |
| ≤125 |
FFLJ.J |
10 |
| 160 |
FFLJ.J |
16 |
| 200-250 |
FFLJ.J |
20 |
| 315 |
FFLJ.J |
25 |
| 400 |
FFLJ.J |
31.5 |
| 500 |
FFLJ.J |
40 |
| 630 |
FFLJ.J |
50 |
| 800 |
FFLJ.J |
63 |
Before ordering Users should provide the following information:
1. Single-line diagram of box-type substation;
2. List of internal components and indicate detailed models and specifications;
3. Are there any special requirements for the installation site of the box-type substation;
4. Other special requirements should be constrained in the order specification or contract;
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