Oil-immersed Test Transformer
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Distribution transformers are one of the important equipment in the power supply and distribution systems of industrial and mining enterprises and civil buildings. They reduce the network voltage of 10(6)kV or 35kV to the 230/400V bus voltage used by users. This type of product is suitable for AC 50(60)Hz, with a three-phase maximum rated capacity of 2500kVA (single-phase maximum rated capacity of 833kVA, single-phase transformers are generally not recommended). It can be used indoors (or outdoors). When the capacity is 315kVA and below, it can be installed on poles. The ambient temperature should not exceed 40°C, not lower than -25°C, with a maximum daily average temperature of 30°C, a maximum annual average temperature of 20°C, relative humidity not exceeding 90% (at an ambient temperature of 25°C), and an altitude not exceeding 1000m. If the above usage conditions are not met, appropriate rating adjustments should be made in accordance with the relevant provisions of GB6450-86.
Product Selection Guide
Oil-immersed transformer, also known as oil-immersed test transformer.
Product Introduction
Oil-immersed transformers of 1000kVA and above must be equipped with outdoor signal thermometers and can be connected to remote signals. Oil-immersed transformers of 800kVA and above should be equipped with gas relays and pressure protection devices. For oil-immersed transformers below 800kVA, gas relays may also be installed according to usage requirements and in consultation with the manufacturer. Dry-type transformers should be equipped with temperature measuring devices as specified by the manufacturer, generally for transformers of 630kVA and above.
Product Classification: According to the number of phases of a single transformer, it can be divided into three-phase transformers and single-phase transformers. In three-phase power systems, three-phase transformers are generally used. When the capacity is too large and subject to transportation constraints, three single-phase transformers can be used to form a transformer bank in three-phase power systems.
Product Classification
According to the number of windings, transformers can be divided into two-winding transformers and three-winding transformers. Usually, transformers are two-winding, meaning there are two windings on the iron core: one primary winding and one secondary winding. Three-winding transformers are used for larger capacity transformers (above 5600 kVA) to connect three different voltage transmission lines. In special cases, transformers with more windings may also be used.
According to structural form, transformers can be divided into core-type transformers and shell-type transformers. If the windings surround the iron core, it is a core-type transformer; if the iron core surrounds the windings, it is a shell-type transformer. The two differ only slightly in structure, with no essential difference in principle. Power transformers are all core-type.
According to insulation and cooling conditions, transformers can be divided into oil-immersed transformers and dry-type transformers. To enhance insulation and cooling, the iron core and windings of oil-immersed transformers are immersed together in a tank filled with transformer oil. In special cases, such as street lighting or mine lighting, dry-type transformers are also used.
Load Nature
2) When seasonal load capacity is large, it is advisable to install dedicated transformers, such as air conditioning chiller loads and electric heating loads for heating in large civil buildings.
3) When concentrated loads are large, it is advisable to install dedicated transformers, such as large heating equipment, large X-ray machines, and electric arc furnaces.
4) When lighting load is large or when sharing a transformer between power and lighting seriously affects lighting quality and lamp life, a dedicated lighting transformer may be installed. Generally, power and lighting share a transformer.
Usage environment: Under normal medium conditions, oil-immersed or dry-type transformers can be selected, such as independent or attached substations in industrial and mining enterprises, agriculture, and community independent substations. Available transformer options include S8, S9, S10, SC(B)9, SC(B)10, etc.
Usage Environment
Electrical load: 1) The capacity of distribution transformers should be determined by integrating the installed capacity of various electrical equipment to calculate the calculated load (generally excluding fire protection load). The apparent capacity after compensation is the basis for selecting transformer capacity and quantity. Generally, the load rate of transformers is about 85%. This method is relatively simple and can be used for estimating capacity.
Electrical Load
2) In GB/T17468-1998 "Guide for Selection of Power Transformers", it is recommended that the capacity selection of distribution transformers be determined according to GB/T15164-94 "Loading Guide for Oil-immersed Power Transformers" or GB/T17211-1998 "Loading Guide for Dry-type Power Transformers" and the calculated load. The above two guides provide computer programs and normal periodic load diagrams to determine the capacity of distribution transformers.
