山东晨宇电气股份有限公司

Series dry-type power transformers Dry-type transformer price pictures
>Dry-type transformers
Rely on air convection for cooling, and are generally used for local lighting and electronic circuits. Mechanical equipment and other transformers, in the power system, generally steam turbine transformers, boiler transformers, ash removal transformers, dust removal transformers, desulfurization transformers, etc. are dry-type transformers with transformation ratios of / and /, used for loads with rated voltage. Simply put, a dry-type transformer refers to a transformer in which the core and windings are not immersed in insulating oil.
Structural features of dry-type transformer
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Iron core
Using high-quality cold-rolled grain-oriented silicon steel sheets, the iron core silicon steel sheets adopt full-bevel joints to allow the magnetic flux to flow along the The direction of the silicon steel sheet seam passes through
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Winding
Compression winding generally adopts a multi-layer cylindrical or multi-layer segmented structure
Compression winding generally adopts a layered or foil structure
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Dry-type transformer form
Casting epoxy resin or other resin casting is used as the main insulation. It has a simple structure and small footprint and is used for smaller capacity transformers
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Characteristics and structure of dry-type transformers
>Compared with oil-type transformers, dry-type transformers do not have oil, so there are no problems such as fire, explosion, pollution, etc. Therefore, electrical specifications and regulations do not require dry-type transformers to be placed in In a separate room. Especially for the new series, the loss and noise have been reduced to a new level, creating conditions for the transformer and the low-voltage panel to be placed in the same power distribution room.
⑴Temperature control system of dry-type transformers
The safe operation and service life of dry-type transformers largely depend on the safety and reliability of the transformer winding insulation. When the winding temperature exceeds the insulation withstand temperature, causing insulation damage, it is one of the main reasons why the transformer cannot work normally. Therefore, monitoring the operating temperature of the transformer and its alarm control are very important.
⑵Protection methods of dry-type transformers
According to the characteristics of the use environment and protection requirements, different shells can be selected for dry-type transformers. A protective shell is usually used to prevent solid foreign objects with a larger diameter and small animals such as rats, snakes, and birds from entering, causing short circuits and power outages and other vicious failures, and provides a safety barrier for live parts. If the transformer needs to be installed outdoors, a protective enclosure can be used. In addition to the above protective functions, it can also prevent water dripping within the angle with the vertical line. However, the outer casing will reduce the cooling capacity of the transformer, so when selecting it, attention should be paid to the reduction in its operating capacity.
⑶ Cooling methods of dry-type transformers
Dry-type transformer cooling methods are divided into natural air cooling and forced air cooling. When naturally air-cooled, the transformer can operate continuously for a long time at rated capacity. When forced air cooling is used, the output capacity of the transformer can be increased. It is suitable for intermittent overload operation or emergency overload operation. Since the load loss and impedance voltage increase greatly during overload, it is in a non-economic operating state, so it should not be placed in long-term continuous overload operation.
⑷ Overload capacity of dry-type transformer
The overload capacity of dry-type transformer is related to the ambient temperature, load condition before overload (initial load), insulation heat dissipation condition of the transformer and heating time constant, etc., if any If necessary, you can obtain the overload curve of the dry transformer from the manufacturer.
At present, my country's annual output of resin insulated dry-type transformers has reached 201, making it one of the countries with the largest production and sales of dry-type transformers in the world. With the promotion and application of low-noise (the noise of the following distribution transformers has been controlled) and energy-saving (the no-load loss is reduced by up to), the performance indicators and manufacturing technology of my country's dry-type transformers have reached the world's advanced level.
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Dry-type transformer technical parameters
>, frequency of use/
, no-load current
, withstand voltage strength/no breakdown test instrument withstand voltage tester ( )
, insulation grade level (special grade can be customized)
, insulation resistance ohm test instrument type one megohmmeter)
, connection method /, △/, /△, auto-coupling type ( Optional)
, coil allowable temperature rise
, heat dissipation method of natural air cooling or temperature-controlled automatic heat dissipation
, noise coefficient
, working environment ℃, relative humidity
, The altitude does not exceed meters.
Precautions
>Avoid exposure to rain, moisture, high temperature, high heat or direct sunlight. There should be no less than a minimum distance between the cooling vents and surrounding objects.
Prevent working in places with a lot of corrosive liquids, gases, dust, conductive fibers or metal chips.
Prevent working in places with vibration or electromagnetic interference.
Avoid long-term upside down storage and transportation, and do not subject it to strong impact.
Dry-type transformer wiring method
> Short-circuit the input and output terminals of the transformer and use a megohmmeter to test the insulation resistance between it and the ground wire. When measured with a megger, the resistance is greater than ohms.
The cross-section wiring of the transformer input and output power cords should meet the requirements of their current value and should be configured according to the current density.
The input and output three-phase power lines should be connected to phase, phase, and phase respectively according to the color yellow, green, and red of the busbar of the transformer wiring board. The neutral neutral line should be connected to the neutral neutral line of the transformer, and the grounding wire And the transformer shell (if the transformer has a box, it should be connected to the ground wire mark of the box).
Check the input and output lines to make sure they are correct.
First, power on without load, and observe and test that the input and output voltages meet the requirements. At the same time, observe whether there are abnormal noises, sparks, odors or other abnormal phenomena inside the machine. If there is any abnormality, please disconnect the input power immediately.
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Check
> No abnormal sound or vibration.
There is no discoloration caused by local overheating and harmful gas corrosion, such as creepage traces and carbonization on the insulation surface.
Check whether the air cooling device of the compressor is operating normally.
. The low-voltage connector should be free of overheating and the cable head should be free of leakage and creepage.
The temperature rise of the group should be based on the insulation material grade used in the transformer, and the monitored temperature rise should not exceed the specified value.
The porcelain bottle should have no cracks or traces of electricity.
Check whether the winding pressing piece is loose.
The internal ventilation and iron core air ducts should be free of dust and debris, and the iron core should be free of rust or corrosion.