Seriesreactornormallyusedintransmissionlinetolimitcurrent,andforelectric furnacetolimitcurrentandstabilizingelectricarc.Itcanbemadeinaircoretypeorsiliconcoretype. Herewemeancoretypeseriesreactor. Advantagetoairtype: 1)Longlifeastransformer 2)Lessworkofmaintenance 3)LessenvironmentpollutionwithoutEMDandnooxenresin 4)Lessareaorspace 5)Less losses.

Seriesreactornormallyusedintransmissionlinetolimitcurrent,andforelectric furnacetolimitcurrentandstabilizingelectricarc.Itcanbemadeinaircoretypeorsiliconcoretype. Herewemeancoretypeseriesreactor. Advantagetoairtype: 1)Longlifeastransformer 2)Lessworkofmaintenance 3)LessenvironmentpollutionwithoutEMDandnooxenresin 4)Lessareaorspace 5)Less losses.

What is residual current transformer
Residual current transformer is the detection element of leakage protector. Its main function is to detect the residual current (grounding fault current such as electric shock and leakage) of the main circuit passing through the transformer core, and convert the residual current of the primary circuit into the output voltage of the secondary circuit. Residual current transformer is one of the most critical components of leakage protector.
Principle of residual current transformer
The principle is based on Kirchhoff's current law: the algebraic sum of the complex current flowing into any node of the circuit is equal to zero. When the line and electrical equipment are normal, the vector sum of each phase current is equal to zero, and the secondary winding of residual current transformer has no signal output; When the vector sum of each phase current in case of grounding fault is not zero, the fault current generates magnetic flux in the annular core of residual current transformer, and the secondary winding will send a signal. When the electrical fire monitoring detector receives the signal, it will send an alarm.
What are the types of residual current transformers
There are many manufacturers, models and brands of residual current transformers in China. The main common products are:
Beijing pfeiler technology fct6200f series residual current transformer; Fujian Junhao JHA / DT series residual current transformer and jha-100a / 225A series residual current transformer;
Sandy electric sd-0.66l residual current transformer;
Schneider ma120, ia80, sa200;
Nanjing Zhending ctz-fl series residual current transformer;
Aokai electric dh-zct series residual current transformer;
Nanjing Zeming zm-lxct01 series residual current transformer;
Shanghai Leining lhy-63a, lhy-100a, lhy-160a, lhy-225a;
Guangdong Chaozhou MS electronic ddb-md series residual current transformer;
Beijing xingdongfang power klh-i, klh-ii, klh-iii;
Shanghai ankerui akh-0.66l residual current transformer, namely akh-0.66l-35, akh-0.66l-70 and akh-0.66l-105;
Hangzhou biaiqi bh-0.66l series current transformer;
Huoyuan technology hct100a-4l, hct206-lf, hct220-lf, hct215-lf, hct210-lf, hct208-lf, hct200b-lf, hct210lf;
Lbd-lct-2, lct-3 and lct-4 of longbaidi in Baoding;
Zibo Tongyue electronic 078 series residual current transformer;
Bengbu Yiai fire, Beijing Fengli Hengan ctz-fl series residual current transformers;
Beijing Huayu Xianfeng dj-lw45 series residual current transformer;
Deyang Shudian power residual current transformer;
Harbin Jiahe and Liancheng (Beijing) technology ccj70 residual current transformer;
Jh-r circular residual current transformer of Beijing Jian'an Cheng Automation Co., Ltd;
Yipukang technology SR series residual current transformer;
Hangzhou dimai technology ct-100a, ct-225a, ct-400a residual current transformer, etc.
Function of residual current transformer
The setting current of residual current transformer protection action can be from Ma level to a level, and the sensitivity is very high. Therefore, it can detect the slight change of leakage current in the electrical circuit. It is used to extract the residual current signal of the monitored line, continuously detect the leakage current of the ground system, convert the primary current with large value into the secondary current with small value through a certain transformation ratio, for protection and measurement, and realize the power monitoring of three-phase system at the same time. When leakage current occurs in the electrical circuit, it will drive the tripping device and switch the power supply network to achieve the purpose of grounding fault protection.
How to select residual current transformer (selection description)
1. Model description
Specification and parameter comparison table
Wiring mode

Fire risk of oil immersed power transformerInsulating gasket and support inside oil immersed power transformer. Most of them use organic combustible substances such as paperboard, cotton yarn, cotton cloth and wood, and there is a large amount of insulating oil (mineral oil with flash point no less than 135 is easy to decompose when heated and can burn in case of open fire).

For example, the 1000KVA transformer uses about 0.012 cubic meters of wood, more than 40 kilograms of paper and 1 ton of insulating oil. In case of serious overload and short circuit inside the transformer, the combustible insulating materials and insulating oil will decompose, expand and gasify under the action of high temperature or arc, resulting in a sharp increase in the pressure inside the transformer, which will seriously cause shell explosion and a large amount of oil injection, The burning oil flow will further expand the fire hazard, cause power failure in the factory and even the whole power supply area, affect normal production and life, and cause huge losses.Fire causes of oil immersed power transformer(1) Insulation damagea. Coil insulation aging. b. Poor oil quality, too little oil. c. Aging and damage of iron core insulation. d. The insulation is damaged due to careless maintenance.(2) Poor contact. Local overheating, damage to coil insulation, short circuit or open circuit, high temperature and arc, rapid decomposition of insulating oil, large amount of gas (80% hydrogen) and sudden increase of pressure. There are three reasons: loose bolts (the transformer often operates under impact load, and the vibration will cause contact looseness), loose welding and damage of tap changer contact.(3) Lightning overvoltage. The overvoltage generated by lightning strikes breaks down the insulation of the transformer, burns the transformer and causes a fire.(4) Load short circuit. When the load is short circuited, the transformer bears huge short-circuit current. If the protection system fails or the setting value is adjusted too much, the transformer may be burned. Short circuit protection device shall be installed, and the melt selection must meet the requirements. In case of internal short circuit of the transformer, the high-voltage side shall be able to fuse quickly. In case of short circuit or serious overload of each outgoing circuit of the transformer, the low-voltage side can be fused.(5) If the transformer is overheated, the service life of the transformer will be affected at least (for example, the service life of the transformer will be 20 years under the normal working temperature of 90 ; if the temperature rises to 105 , the service life will be 7 years; if the temperature rises to 120 , the service life will be only 2 years), or fuel injection combustion or explosion will occur at most. The causes of transformer overheating are: poor contact and high contact resistance; Long term serious overload operation causes coil heating; If the voltage is too high, the iron loss will increase (when the voltage increases by 10%, the iron loss will increase by 30% 50%); The ambient temperature is too high and the ventilation is poor;

(6) The transformer is ignited by an external fire source. The combustibles stacked around the transformer ignite the transformer or transformer chamber after combustion, causing the transformer to catch fire.Fire prevention measures for oil immersed power transformerThe selection is reasonable and of high quality, which can withstand the sudden short circuit at the secondary line end without damage; Provide explosion-proof pipe (diameter and shape suitable) lightning protection facilities, fuse and other protective devices as required; The transformer shall be carefully inspected and tested before installation and after maintenance to prevent insulation damage; During operation, patrol inspection shall be carried out carefully to pay attention to whether the transformer oil leaks, whether the oil level is too low and whether the oil temperature is too high (no more than 75 ); Whether the load exceeds the rated capacity. The transformer oil shall be sampled and tested regularly. If the flash point is lower than 135 , it shall be treated or replaced in time. If you hear abnormal sound in the transformer, check it immediately.

1) Insulation performance: increase the insulation strength of various components in the transformer. The oil insulation strength of the transformer is good and has fluidity. It can fill all parts and any space of the transformer and discharge the air, so as to avoid moisture contact between the parts and the air and affect the insulation strength, so as to maintain good insulation between windings, between windings and iron core, and between windings and oil tank shell.2) Heat dissipation performance: the transformer oil cools the iron core and winding of the transformer. During the operation of the transformer, the temperature of the oil near the winding and iron core increases after heating, the volume expands, the specific gravity decreases and rises, and then enters the bottom of the transformer oil tank after cooling by the cooling device, so as to form oil circulation. During the cycle, heat is radiated to the cooling device, so that the iron core and winding are cooled.3) Anti corrosion performance: transformer oil can keep the original chemical and physical properties of insulating materials (such as wood) and make metals (such as steel) play an anti-corrosion role

General principles for power transformer when supplementary oil is requireda) Transformer oils with different oil bases shall not be used together;b) Oils of different grades (freezing point) of the same oil base shall not be used together;c) The quality of mixed oil shall comply with the provisions of gb7595;d) When new oil or transformer oil of the same oil base and different grades equivalent to the quality of new oil is mixed, its availability shall be determined according to the measured freezing point of the mixed oil. It cannot be mixed only according to the qualified chemical and electrical properties:e) When the in-process oil is mixed with new oil of the same brand, the oxidation stability test of the mixed oil sample shall be carried out in advance, and the mixed oil can be used only when there is no sediment.f) When imported oil or oil of unknown source is mixed with operating oil of different brands, the aging test of various oils and mixed oil samples shall be carried out in advance. The mixed oil can be used only when the quality of the mixed oil is not lower than that of the original operating oil; If the mixed oil is new oil, the quality of the mixed oil shall not be lower than the worst new oil.What are the protective functions of power transformerRole of gas protectionThe main protection measure in the transformer is gas protection. The reduction of transformer oil level and the faults in transformer oil tank are reflected by gas. When the transformer has a slight fault, the oil level will drop, and the light gas will send a signal. When the gas has a serious fault, a large amount of gas will be generated, and the heavy gas will also trip.When there is a fault in the transformer, there will be heating in the fault part. In this way, the oil expansion will occur in the nearby transformer, the air will be discharged and the bubbles will gradually rise, while other materials and oil will produce gas under the action of discharge, so as to reduce the oil level.When the fault is very serious, after the gas gas is generated, the pressure inside the transformer is increased, so that the oil flows to the conservator. The baffle will overcome the resistance of the spring when the oil flow impacts, so as to move the magnet towards the dry spring and connect the contact of the dry spring. In this way, tripping will occur.

Function of differential protectionDifferential protection is the main protection of the transformer, which mainly reflects the faults of the outgoing line and winding of the transformer. It can trip the circuit breakers on each side of the transformer. According to different devices, differential protection can be divided into the following types: transverse differential protection is often used in shunt capacitor and short-circuit protection. When the equipment adopts double bus and double winding, transverse differential protection will be adopted; Longitudinal differential protection mainly reflects short circuit and inter turn short circuit, and the protection scope mainly includes outgoing line and bushing.Backup protectionThe main transformer has the characteristics of large impedance during operation. Therefore, the fault of the main transformer on the low-voltage side will not affect the operation of the high-voltage side. The stability of high voltage side can effectively realize the protection function of voltage locking. However, when the main transformer fault is abnormal during operation, it can not respond in time. Therefore, during the operation of the main transformer, backup protection measures shall be taken. The parallel opening mode of high-voltage side and low-voltage side can be adopted to make the opening of locking circuit flexible.Function of voltage and current protection of transformerWhen a fault occurs outside the transformer, overcurrent will be generated; When there is an internal fault in the transformer, the backup of differential protection and gas protection will be generated. In the transformer, current protection devices should be installed. Different protection methods are selected according to different transformer capacity and system short-circuit current.The requirements for current transformer for relay protection are: reliable insulation; A sufficiently large accuracy limit factor; Sufficient thermal and dynamic stability. The transformer for protection can meet the requirements of accuracy level under rated load. The maximum primary current is called rated accuracy limit primary current. The accuracy limit factor is the ratio of the rated accuracy limit primary current to the rated primary current. When the primary current is large enough, the iron core will be saturated and can not reflect the primary current. The accurate limit coefficient represents this characteristic. The accuracy grade of transformer for protection is 5p and 10p, indicating the allowable error of 5% and 10% at the rated accuracy limit primary current.