Temperature regulations for dry-type transformers

Temperature regulation for operating environment of dry-type transformers

During inspection, the equipment should be carried out in a intact and enclosed area or a temporary sealed area. The road surface should be flat and firm, and the surrounding area should be cleaned. Machinery, equipment, and special tools should be washed clean to prevent pollution, rain and snow weather, and pollution control. The working temperature should be between 7-16 ℃. When the temperature of the transformer body is lower than the working temperature, the body should be heated to make the body temperature 12 ℃ higher than the working temperature. But when the relative humidity is below 65%, no heating can be applied. During inspection, the equipment should be carried out in a intact and enclosed area or a temporary sealed area. The road surface should be flat and firm, and the surrounding area should be cleaned. Machinery, equipment, and special tools should be washed clean to prevent pollution, rain and snow weather, and pollution control. The working temperature should be between 7-16 ℃. When the temperature of the transformer body is lower than the working temperature, the body should be heated to make the body temperature 12 ℃ higher than the working temperature. But when the relative humidity is below 65%, no heating can be applied.

During the operation of the transformer, various safety factors and safety effects must be continuously improved. The operation of the transformer is very safe, and its characteristics must be in a safe and natural environment. Only when the standard is suitable and the natural environment is appropriate can the transformer operate safely. Otherwise, it will not be easy for the transformer to operate normally and common faults will occur. Therefore, the operation of the transformer must be suitable for the natural environment, and the output power of the transformer must be continuously established for smoother operation.

Electric power engineering is essential for everyone's clothing, food, housing, and transportation. In the absence of energy supply, emergency rescue and disaster relief cannot be carried out in an orderly and normal manner, leading to secondary disasters. The safety production of electricity has been elevated to an unprecedented aspect ratio. Under normal circumstances, social and economic development also leads to a sharp increase in power consumption. Therefore, it is necessary to pay special attention to the safety of transformer operation by providing multiple levels. The first step is to effectively open a store and select a location, and controlling the operation of transformers must have an excellent environmental factor.   

Wet and cold, low-lying, high temperature, ultra-low temperature, saline alkali land, strong dust and other areas are all hazards to the operation of transformers. Poor natural ventilation can also cause explosions in control transformers. Choose appropriate protection methods. Relay protection devices are a more reliable protection method. The transformer is a key component in the power supply system. The decision on the relative protection method is based on the consideration of the load capacity of the control transformer and its own usage value. At the same time, it is necessary to actively and scientifically research new products to cope with the harm caused by the increasingly extreme geographical environment to control transformers. Transformers are a key component of the power grid and have the ability to adjust the rated voltage. The important process of designing, producing, and investing funds in the application of transformers must ensure safety as the mainstay, with a focus on maintenance and upkeep. Improving the safety performance of control transformers plays a particularly important role in ensuring the safe production of electricity across the entire power grid.   

The natural environment and its impact on the operation of transformers are the main manifestations of their hazards. Therefore, it is necessary to improve the safety of the operation of transformers through natural environment testing, establish more oasis advantages for transformers, and make the operation of transformers more promising for China Life Insurance. Only then can transformers become more efficient!

Temperature protection regulations for dry-type transformers

During the operation of dry-type transformers, customers often forget to carry out maintenance, which leads to an increase in the temperature control system of dry-type transformers and prolongs the service life of machinery and equipment.

The temperature control system, safe operation, and service life of dry-type transformers largely depend on the reliability of the transformer's winding resistance insulation layer. When the winding resistance temperature of a dry-type transformer exceeds the tolerance temperature of the insulation layer, causing damage to the insulation layer, it is one of the key reasons that prevent the normal operation of the transformer. Therefore, the detection of the operating temperature of the transformer and the operation of the alarm are crucial. So, what are the main things to pay special attention to? Follow Fuzhou Yinuo Technology's temperature controller below to learn more.

1、 Automatic control system for centrifugal fans:

According to the temperature data signal measured by the Pt100 thermistor temperature measurement resistor at the hottest point of the bottom pressure winding resistance of the embedded parts, the load of the transformer expands and the operating temperature rises. When the winding resistance temperature reaches 120 ℃, the system starts the centrifugal fan for water cooling. When the winding resistance temperature drops to 95 ℃, the system terminates the centrifugal fan.

2、 Overheat alarm, power trip:

Dry type transformers collect winding resistance or core temperature data signals based on the PTC discrete system thermal temperature measurement resistor embedded in the bottom pressure winding resistance. When the winding resistance temperature of the transformer rises again and exceeds 155 ℃, the system software outputs an overheat alarm system; If the temperature rises again to 171 ℃ and the transformer can no longer operate, it is necessary to send the overheat tripping data signal to the maintenance control circuit conveyor again. The transformer should be quickly tripped.

Temperature regulation for winding of dry-type transformers

If the temperature of a dry-type transformer in normal operation exceeds 96 degrees, it is already considered high and the load cannot be further increased.

Bottom pressure machine equipment usually requires that the leakage current does not exceed 65 degrees (i.e., operating temperature+65 degrees). Excessive temperature accelerates the embrittlement of the insulation layer of machine equipment, reducing its service life.

150kva three-phase dry type transformer (safety protection type)

The most immediate method is to persist for about 12 seconds when using a mobile device. Persistently unable to rise, even if the temperature is high, look at what high temperature resistance level your transformer has. At present, in China, dry-type transformers are classified according to flame retardant levels, including (A) level, (E) level, (B) level, (F) level, (H) level, and (C) level. Transformers can be divided into 7 high-temperature resistance levels based on their high-temperature resistance level: A, E, B, F, H, and C. Different types of thermal conductive materials have different high-temperature resistance working abilities. Generally, the flame retardant level of oil immersed transformers is classified as Grade A.

Maximum allowable temperature (℃) 106 130 140 155 190,

Temperature rise limit for winding resistance (K) 65 70 90 150 250

Characteristic reference temperature (℃) 90 96 150 130 155

The flame retardant level of a transformer is not a definition of the compressive strength of the insulation layer, but a specification of the allowable leakage current. That is, the flame retardant level refers to the high-temperature resistance level of its commonly used thermal conductive materials, divided into A, E, B, F, and H. The main allowable leakage current specifications for each flame retardant level are as follows:

The insulation layer (insulation paint for pure cotton yarn, silk, and general enameled wire that has undergone insulation layer impregnation) has a permissible raw material temperature of 106 degrees Celsius, a rated operating temperature of 96 degrees Celsius, and a maximum control value of 160 degrees Celsius (exceeding this leakage current will result in insulation layer wear and tear exceeding the allowable range). E-grade insulation layer (insulation paint for epoxy resin adhesive, triacetate fiber plastic film, polyester film, and high toughness enameled wire) has a permissible raw material temperature of 130 degrees Celsius, a rated operating temperature of 120 degrees Celsius, and a maximum control value of 155 degrees Celsius (exceeding this leakage current will result in insulation layer wear and tear exceeding the allowable range).

B-level insulation layer (inorganic compounds such as mica, fiberglass, and asbestos are bonded or impregnated with organic chemical raw materials). The allowable temperature of the raw materials is 140 degrees Celsius, the rated operating temperature is 130 degrees Celsius, and the maximum control value is 162 degrees Celsius (beyond this leakage current, the wear rate of the insulation layer will exceed the allowable range).

F-class insulation layer (inorganic compounds such as mica, fiberglass, and asbestos are bonded or impregnated with unique organic chemical raw materials, such as synthetic resin paint modified with silicone organic materials as the adhesive). The allowable temperature of the raw materials is 155 degrees Celsius, the rated operating temperature is 155 degrees Celsius, and the maximum control value is 180 degrees Celsius (beyond this leakage current, the wear rate of the insulation layer will exceed the allowable range).

H-class insulation layer (mica, fiberglass, asbestos and other inorganic compounds are bonded or impregnated with unique organic chemical raw materials, such as using silicone organic chemical paint for bonding or impregnation, silicone organic chemical vulcanized rubber, inorganic filler). The allowable temperature of the raw materials is 190 degrees Celsius, the rated operating temperature is 180 degrees Celsius, and the maximum control value is 230 degrees Celsius (beyond this leakage current, the wear rate of the insulation layer will exceed the allowable range).

C-grade insulation layer (special paper type, laminated board, etc., such as aromatic polyamide high polymer) has a permissible temperature of 230 degrees Celsius for raw materials, a rated operating temperature of 260 degrees Celsius, and a maximum control value of 350 degrees Celsius (exceeding this leakage current will result in insulation layer loss exceeding the allowable range).

According to GB1094.11, the rated operating standard for dry-type transformers is an altitude not exceeding 150 meters, with an average temperature of 40 degrees Celsius in the hottest month and a maximum annual average temperature of 30 degrees Celsius. The lowest temperature for outdoor dry-type transformers is -20 degrees Celsius, and the lowest temperature for indoor dry-type transformers is -5 degrees Celsius. Under this standard, the allowable leakage current of the dry test transformer varies due to different flame retardant levels. The average temperature rise limit under the rated voltage of Class A insulation layer is 65K, Class E insulation layer is 70K, Class B is 90K, Class F is 150K, and Class H is 250K. If the operating standard is not the required standard, the temperature rise limit must be confirmed by the buyer and seller after discussion. The higher the temperature, the greater the resistance of the dry-type transformer winding, and the greater the overheating, which will reduce the efficiency. This is a positive feedback problem. If it is an F-level insulation layer system software, it is more suitable to operate normally at 60-65 ℃.

Temperature regulation for 10kV dry-type transformers

Usually, it is necessary to improve the observation of temperature controllers to see if the displayed three-phase electrical temperature is balanced, and if there is a genetic mutation problem in the displayed temperature information value of a certain phase. At present, the connector between the temperature controller and the internal thermistor (temperature measurement) of the transformer is a pin type power plug. If it is loose, it will cause the temperature controller to misdistinguish. But if monitoring is improved, the abnormal working attitude of the temperature controller will be detected, and effective measures will be taken early to prevent the occurrence of common faults. For capacity transformers and transformers in critical locations, it is possible to specify that the transformer manufacturer install an additional thermistor per phase when ordering, and establish a bidirectional configuration for the temperature controller, which can effectively prevent the occurrence of such common faults.

In some relatively humid and cold areas (such as areas with high precipitation and low light), if a stopped dry-type transformer is turned on, it is necessary to check if there is any abnormal dampness or cold. If not, start the warm air to dry the surface and prevent thermal breakdown of the insulation layer. For oxygen cast dry-type transformers, this type of wet and cold surface layer does not pose a threat to the insulation layer inside the winding resistance. Therefore, after solving this problem, funds can be put into operation. If the funds of the transformer are put into operation, the heat generated by its consumption will restore the grounding resistance.

Operating temperature of 10kV dry-type transformer

The characteristics of dry-type transformers are different from those of oil immersed transformers. If the winding operates at higher temperatures for a long time, although it is allowed, it can accelerate the embrittlement of the insulation layer and reduce the service life of dry-type transformers. Therefore, the load rate of dry-type transformers should be considered to leave sufficient capacity, and special attention should be paid to the operating temperature of dry-type transformers not to be too high. C-level transformers allow for higher temperatures, and dry-type transformers in normal operation with temperatures exceeding 96 degrees Celsius are already considered higher. We can't increase the load anymore. Bottom pressure machine equipment usually requires that the leakage current does not exceed 65 degrees (i.e., operating temperature+65 degrees). Excessive temperature accelerates the embrittlement of the insulation layer of machine equipment, reducing its service life. The limit value of 250K is for H-class insulation layer.

The national industry standard GB6450-1986 specifies the temperature rise limit for dry-type transformers. 1. For the electromagnetic coils of dry-type transformers, when using A-grade thermal conductive materials, the maximum leakage current should be less than 65K when the maximum operating temperature is 106 ℃; When using E-grade thermal conductive materials, the maximum leakage current should be less than 70K when the maximum operating temperature is 130 ℃; When using B-grade thermal conductive materials, the maximum leakage current should be less than 90K when the maximum operating temperature is 140 ℃; When using F-grade thermal conductive materials, the maximum leakage current should be less than 150K when the maximum operating temperature is 155 ℃; When using H-grade thermal conductive materials, the maximum leakage current should be less than 250K when the maximum operating temperature is 190 ℃; When using C-grade thermal conductive materials, the maximum leakage current should be less than 130K when the maximum operating temperature is 230 ℃. Nowadays, most dry-type transformers use H-grade thermal conductive materials, so it is generally said that the temperature of dry-type transformers should be below 190 ℃.

Is it dangerous for dry-type transformers to operate at a temperature of 95 degrees Celsius

Is the operating temperature of SCB10 dry-type transformer 96 degrees safe?

The national industry standard GB6450-1986 specifies the temperature rise limit for dry-type transformers.

1. For the electromagnetic coils of dry-type transformers, when using A-grade thermal conductive materials, the maximum leakage current should be less than 65K when the maximum operating temperature is 106 ℃; When using E-grade thermal conductive materials, the maximum leakage current should be less than 70K when the maximum operating temperature is 130 ℃; When using B-grade thermal conductive materials, the maximum leakage current should be less than 90K when the maximum operating temperature is 140 ℃; When using F-grade thermal conductive materials, the maximum leakage current should be less than 150K when the maximum operating temperature is 155 ℃; When using H-grade thermal conductive materials, the maximum leakage current should be less than 250K when the maximum operating temperature is 190 ℃; When using C-grade thermal conductive materials, the maximum leakage current should be less than 130K when the maximum operating temperature is 230 ℃.

2. The transformer core, metal components, and adjacent raw materials between them are not prone to temperatures that can cause harm to the transformer core itself, other components, or adjacent raw materials between the two under all conditions. Nowadays, most dry-type transformers use H-grade thermal conductive materials, so it is generally said that the temperature of dry-type transformers should be below 190 ℃.

What is the lifespan of a dry-type transformer operating at a temperature of 95 degrees Celsius

Dry type transformers can be used normally at temperatures not exceeding 155 ℃. But if the temperature of the dry-type transformer is too high, it will gradually cause the insulation layer to become brittle, and the lower the temperature of the transformer, the higher it will be. Under normal application, dry-type transformers can last for about 30 years.

In fact, because the actual working temperature of electricity consumption changes throughout the year, the temperature may exceed its temperature specifications in summer and generally be lower than the temperature specifications in winter. But if the average fluctuation of the resistance temperature throughout the year does not exceed 155 ℃, its embrittlement rate can still be within all normal and acceptable ranges.

The leakage current of dry-type transformers does not exceed 75 ℃. If the temperature is too high, it will accelerate the embrittlement of the insulation layer inside the machine equipment. If it is necessary to adjust the working temperature of the transformer during operation, it can be controlled below 60 ℃. Usually, the factory sets up a 95 ℃ starting centrifugal fan heat pipe for heat dissipation, a 130 ℃ starting high temperature alarm, and a 165 ℃ ultra-high temperature will trip the power. The higher the temperature during operation, the greater the resistance, and the continuous increase in heating value. The high efficiency will sharply decrease, which is a positive feedback problem. If it is an F-level insulation layer system software, it is more suitable to operate normally at 50-65 ℃. Under basic conditions, if the temperature of a dry-type transformer in operation exceeds 97 ℃, it is already considered relatively high. Please do not increase the load any further. The bottom pressure machine equipment usually stipulates that the leakage current does not need to exceed 63 ℃. Excessive temperature accelerates the embrittlement of the insulation layer of machine equipment, reducing its service life.

• Prev：BWDK-S201G Dry type Transformer Temperature Controller
• Next：Top Ten Advantages of Dry-Type Transformer Temperature Controllers