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What are the precautions for live oil filtration? (1) Throughout the entire process of live oil filtration and degassing, the gas relay circuit of the transformer must be connected to the signal circuit to prevent gas leakage and oil running in the pipeline, causing the oil switch to trip and resulting in a large-scale power outage. (2) The pipelines and joints connecting the oil filter machine and the transformer must be securely tied, with no occurrence of rupture, damage, or gas leakage. (3) For forced oil-cooled and water-cooled transformers, the connected cooler oil pump should not be started, as the excessive oil pump flow can cause the heater of the […]

How are the deviation values of transformer parameters and the parameters using peak values specified? The specifications for evaluating the performance parameters of transformers are determined by technical conditions, and each standard value has corresponding deviation values, which can be categorized into several types: (1) Parameters with only a lower limit specified, without an upper limit, where larger values are better: a.Absorption ratio, insulation resistance; b. Distance between bushings with voltage; c. Insulation withstand capability; d. Local discharge test time and frequency, AC withstand voltage test time and frequency; e. Electrode surface; f. Number of impulse short-circuit tests; g. Number of impact tests; h. Electrical and mechanical lifespan of on-load

How is the testing of transformer oil conducted? The dielectric strength test of transformer oil is conducted using a 500mm³ standard oil cup in a 60kV AC frequency oil tester. The brass electrodes of the oil cup have a diameter of 25mm, and the surface cleanliness is as shown in Figure 92—6, with an electrode spacing of 2.5mm. Firstly, the oil cup is rinsed with the test oil for at least three times. Subsequently, the test oil is poured into the cup until it reaches 10mm below the cup’s rim, and then left undisturbed for 10 minutes to eliminate bubbles. The voltage is gradually increased until breakdown occurs, and the

How is the measurement of insulation resistance and absorption ratio conducted? Insulation resistance, denoted as R, is typically determined by applying a voltage of 2500V for 60 seconds and measuring the resulting value using a megohmmeter with a maximum range of 10000 MQ. Due to variations in the stability of insulation resistance arising from differences in product geometry, structure, material, and moisture content within the insulation, there is no standardized value for R. To provide a rough constraint on R and depict its relationship with temperature, the absorption ratio (Ro/Rs) is the ratio of insulation resistance measured during direct current application for 60 seconds and 15 seconds (for large transformers,

What is the basic concept of overvoltage? In the operation of various electrical equipment in power systems, besides withstanding normal system voltages, they also encounter various types of overvoltages. Overvoltages are generally classified into two categories based on their sources: external overvoltages and internal overvoltages. External overvoltages typically refer to lightning-induced overvoltages. Internal overvoltages refer to voltage increases caused by changes in system parameters due to circuit breaker operations, system faults, or other reasons, leading to the conversion or transfer of electromagnetic energy within the power grid. Contact LuShan, est. 1975, is a Chinese professional manufacturer specializing in power transformers and reactors for 50+ years. Leading products are single-phase transformer,

Yyy connection：What are the characteristics ? The Yyy connection exhibits third harmonic voltage, but in three-phase three-legged core transformers, the third harmonic voltage does not exceed 5% of the fundamental. Therefore, it is suitable only for three-phase three-legged core medium to large transformers and cannot be used for three-phase five-legged transformers. Contact LuShan, est. 1975, is a Chinese professional manufacturer specializing in power transformers and reactors for 50+ years. Leading products are single-phase transformer, three-phase isolation transformers, electrical transformer, distribution transformer, step down and step up transformer, low voltage transformer, high voltage transformer, control transformer, toroidal transformer, R-core transformer; DC inductors, AC reactors, filtering reactor, line and load reactor, chokes,

Yyd and Ydd Connection : What are the characteristics? The Yyd connection is suitable for transformers with various core configurations, and its features include: (1) The adoption of d-shaped winding on the low-voltage side allows for the elimination of third harmonic voltage. (2) The d-shaped winding can serve as the main winding for power transmission or solely as a stable winding to eliminate third harmonic voltage (not connected to the load). If used exclusively for eliminating third harmonic voltage, its short-term thermal capacity should be equal to 1/3 of the main winding. (3) The presence of the d-shaped winding ensures the stability of the neutral point in the Y-shaped winding.

Yd and Dy Winding Configurations: What are the characteristics? The Yd winding configuration is suitable for transformers with various core forms and features: a. The third harmonic current can circulate through the secondary side, eliminating the third harmonic voltage. b. The neutral point on the primary side can be grounded; since the secondary side adopts the D-shaped winding, the neutral point on the primary side is stable. Therefore, the Yd winding configuration is mainly used in large-scale step-down transformers. If the Dy winding configuration is used, it has similar characteristics to the former but can be applied to step-down transformers for four-wire system supply and large-scale step-up transformers. Contact LuShan,

What is the winding configuration of a transformer? ​ The combination of the connection methods for the high, medium, and low voltage windings of a transformer is referred to as the winding configuration. The winding configuration is crucial for the performance, manufacturing cost, and operational characteristics of the transformer. Common winding configurations for dual-winding three-phase transformers include Yy, Yd, and Yz; for three-winding three-phase transformers, configurations like Yyd, Yyy, Yad, and Yay are commonly used. Contact LuShan, est. 1975, is a Chinese professional manufacturer specializing in power transformers and reactors for 50+ years. Leading products are single-phase transformer, three-phase isolation transformers, electrical transformer, distribution transformer, step down and step up