Oil-filled voltage-regulating transformer
1. Equipped with a 7-position on-load tap changer (OLTC), which makes it possible to maintain a stable low-voltage output — an optimal solution for power grids with significant voltage fluctuations.
2. ONAN-type design (oil-immersed transformer with natural air cooling): the absence of rotating auxiliary equipment ensures minimal maintenance requirements and high operational reliability.
3. Passes comprehensive testing in accordance with national standards; it features reinforced insulation, high resistance to short-circuit currents, and excellent sealing that minimizes the risk of oil leakage.
4. Comprehensive technical support is provided directly by the manufacturer, including assistance with tender participation and on-site installation supervision.
Product name: Oil-immersed voltage-regulating transformer
Product model: S-500/44
Rated power: 500 kVA
Rated frequency: 50 Hz
Connection group: YN0d11
Cooling method: ONAN (oil natural air natural cooling)
Short-circuit impedance: 8.4%
Insulation level: L200 AC95 / AC5
Manufacturing standards: GB 1094.1 “Power Transformers — Part 1: General Provisions”; GB/T 6451 “Technical Parameters and Requirements for Oil-Immersed Power Transformers”
Structural characteristics
1. Magnetic core (core): Made of cold-rolled grain-oriented electrical steel with high magnetic permeability. During assembly, the stepped-lap method of joining the sheets is used, which minimizes no-load losses and noise levels. The magnetic core is securely clamped, which ensures high mechanical strength and a minimal level of vibration during operation.
2. Windings: The high-voltage and low-voltage windings are made of high-quality insulated conductors with multilayer insulation. After vacuum drying and impregnation with transformer oil, the windings acquire stable insulation characteristics and high resistance to electrodynamic forces arising during short circuits, which allows them to withstand sharp surges of short-circuit currents.
3. Tank and cooling system: The welded steel tank is equipped with external corrugated radiators that ensure heat removal through natural convection of the transformer oil (ONAN cooling system — natural circulation of oil and air). The absence of rotating elements such as fans or oil pumps reduces the likelihood of faults. All welds of the tank undergo leak testing, which guarantees reliable isolation of the internal environment, preventing oil leakage and moisture ingress inside.
4. On-load tap changer (OLTC): The built-in 7-position OLTC allows changing the transformation ratio without disconnecting the transformer from the network. This makes it possible to compensate in real time for voltage fluctuations on the high-voltage side, maintaining a stable voltage level on the low-voltage side. The design of the OLTC is characterized by wear resistance and the presence of an arc suppression system, which effectively suppresses the electric arc during switching, thereby extending the service life of the equipment.
5. Auxiliary equipment
High and low voltage bushings: Porcelain insulators resistant to contamination and environmental factors; designed to bring current-carrying parts outside while providing the necessary electrical insulation.
Oil level indicator: Provides visual monitoring of the oil level in the tank, which simplifies regular inspections by maintenance personnel.
Safety valve: Automatically relieves pressure in the event of sudden internal damage, protecting the tank structure from destruction.
Temperature monitoring devices: Sensors are provided for measuring the temperature of the upper oil layers, which allows remote monitoring and tracking changes in the operating temperature of the equipment in real time. Oil drain valve and oil fill port: designed for convenient oil filling at the operation site, sampling oil for laboratory analysis, and draining oil during maintenance.
Operating conditions and application requirements
1. Installation conditions: the equipment is suitable for installation both indoors and outdoors; it is optimal for industrial enterprises, power supply systems of mining facilities, renewable energy-based power installations, as well as for overseas power transmission and distribution projects.
2. Environmental requirements: ambient air temperature range — from -20°C to +40°C; installation altitude — no more than 1000 m above sea level (adaptation for operation at higher altitudes is possible); permissible relative humidity — no more than 85%; absence of aggressive gases and strong vibrations in the environment.
3. Operating environment: high-quality mineral transformer oil is used as the insulating, cooling and arc-quenching medium; before shipment, vacuum oil filling is performed to minimize the content of air bubbles and ensure the required dielectric strength of the insulation.
Protection functions: provision is made for connecting external relay protection devices; the equipment is equipped with overcurrent, instantaneous tripping, and gas (Buchholz relay) protection systems, which ensure tripping in the event of faults and the transmission of alarm signals.
Factory tests
Before shipment, each transformer undergoes a full range of tests in accordance with national standards. The test program includes checking the DC resistance of the windings, the transformation ratio and winding connection group, insulation resistance, power-frequency withstand voltage and induced voltage tests, measurement of no-load and short-circuit losses, as well as partial discharge testing. Based on the test results, a detailed report is drawn up that meets the requirements for equipment acceptance both on the domestic market and within the framework of foreign projects.
