×
  • You must be logged in to create new topics.

後藤 零

後藤 零

Forum Replies Created

Viewing 20 posts - 1 through 20 (of 66 total)
  • Author
    Posts
  • in reply to: Why is step up transformer used in power transmission? #332361
    後藤 零
    Member

    Stepping voltage up reduces current and I²R losses, improving line efficiency and enabling long-distance bulk power transfer.

    in reply to: do transformers consume power when not in use? #331991
    後藤 零
    Member

    Yes. Even without load, transformers draw magnetizing current and incur core losses (hysteresis and eddy currents). Large oil-filled units may also have auxiliary consumption from cooling fans, pumps, and monitoring equipment.

    in reply to: What causes power transformer hum in grid equipment? #331867
    後藤 零
    Member

    Transformer hum is primarily caused by magnetostriction in the core. As magnetic flux reverses each cycle, core laminations slightly expand and contract, creating mechanical vibrations at twice the line frequency (100/120 Hz) and harmonics. Loose clamping, aging insulation, and structural resonances in the tank, radiators, and mounting structures can amplify the audible noise. High load levels and harmonics further intensify the vibration. Proper core clamping, damping materials, and acoustic design are used to reduce hum in substations.

    後藤 零
    Member

    They connect generation to transmission, and transmission to distribution, enabling efficient long-distance transfer and safe end-user supply.

    後藤 零
    Member

    Substation power transformers (tens to hundreds of MVA) cost from hundreds of thousands to several million USD depending on voltage class and cooling.

    in reply to: Who are major power distribution transformer manufacturers? #331365
    後藤 零
    Member

    Major distribution transformer manufacturers include global OEMs and numerous regional producers that specialize in MV/LV step-down units and pole- or pad-mount transformers. They supply utilities, rural electrification schemes, and industrial/commercial campuses. Key capabilities are high-efficiency core designs, eco-friendly fluids, standardized ratings, and fast delivery. Many manufacturers focus on 25-5,000 kVA classes, offering both oil-filled and dry-type construction for indoor and outdoor use.

    後藤 零
    Member

    The CMM-G is designed for rapid servicing, capable of completing the full oil change cycle – draining, flushing, and refilling – in less than one hour. This quick turnaround helps minimize turbine downtime, improving overall wind farm availability and reducing lost production from extended maintenance windows.

    後藤 零
    Member

    LFD is best suited for medium and large power transformers, typically from 5-10 MVA and above, where the mass of cellulose insulation is high and conventional external heating becomes inefficient. It is especially effective for HV and EHV units with thick windings, disc insulation, and long moisture diffusion paths. For small distribution transformers, the complexity and setup effort of LFD is usually not justified, while for large grid transformers it is often one of the most efficient deep-drying methods available.

    後藤 零
    Member

    HV power transformers connect generation to transmission networks, step-up for long-distance lines, and step-down for substation distribution.

    後藤 零
    Member

    Yes – a 60 Hz breakdown voltage test is generally acceptable as long as it’s performed to the correct standard and you report it that way. The common BDV standards treat “power frequency” as a band, not a single number: ASTM D877 specifies an AC test in the 45-65 Hz range, so 60 Hz is within spec. IEC 60156 is also a power-frequency method (typical sources are around 50/60 Hz). What matters more than 50 vs 60 is that you keep everything else consistent (electrode type/gap, voltage rise rate, oil temperature, conditioning, and cleanliness). If you’re trending results, don’t mix methods (e.g., D1816 vs D877 vs IEC 60156) without clearly separating them.

    後藤 零
    Member

    In practice, the limit is not defined by the TOR-5 hardware itself, but by the server configuration and the SCADA or web interface used to display the data. A single TOR-5 server can usually handle dozens of transformers in parallel, as each unit only transmits a small set of parameters with low data rate. The real constraint is screen ergonomics: most operators comfortably monitor 8-16 transformers on one dashboard, using grouping and alarms rather than trying to view everything at once.

    in reply to: What is the function of a power transformer? #330282
    後藤 零
    Member

    A power transformer transfers electrical energy between voltage levels using electromagnetic induction while providing isolation and impedance.

    in reply to: What information is listed on a power transformer nameplate? #330262
    後藤 零
    Member

    A nameplate lists manufacturer, serial number, year, kVA/MVA rating, primary and secondary voltages, connection vector group, frequency, cooling class, impedance, temperature rise, insulation levels, weight, oil volume and standards. Some nameplates show tap ranges and no load/load losses. Nameplates identify the unit and define its electrical capabilities for operators, protection engineers and maintenance personnel.

    後藤 零
    Member

    GlobeCore specializes in oil purification equipment, not solvent-based DCM drying systems. For this application, a chemical-grade zeolite dryer from a solvent-processing supplier would be required.

    後藤 零
    Member

    La máquina GlobeCore para aceites dieléctricos elimina agua (<10 ppm), gases y partículas, restaurando la rigidez dieléctrica. Se utiliza en mantenimiento de transformadores, subestaciones y centros de distribución eléctrica.

    in reply to: What is the oil filtration process for industrial oils? #325082
    後藤 零
    Member

    The oil filtration process includes preheating, coarse and fine filtration, vacuum drying, and degassing. GlobeCore systems automate this entire cycle, ensuring oils meet operational specs. They’re used in energy, mining, metal processing, and aviation sectors.

    in reply to: What is a breakdown voltage tester and how does it work? #324960
    後藤 零
    Member

    It applies increasing voltage until the oil fails electrically. To get valid results, the oil must be moisture-free. GlobeCore’s vacuum dehydration machines are used globally to prepare oils for BDV testing in power substations.

    in reply to: What is AeroShell 308 and where is it used? #323822
    後藤 零
    Member

    AeroShell 308 is a synthetic ester-based turbine oil for jet engines requiring high-temperature protection. GlobeCore systems clean and dry AeroShell 308, extending its operational life.

    in reply to: What is Exxon Turbo Oil 2380 and how is it serviced? #323754
    後藤 零
    Member

    Exxon Turbo Oil 2380 is a synthetic jet engine oil formulated for low deposit formation and long drain intervals. GlobeCore purification units remove moisture and gases, extending its usable life.

    in reply to: Why is transformer filtration needed and how is it done? #323514
    後藤 零
    Member

    Filtration removes particulates, moisture, and gases from insulating oil, restoring its breakdown voltage and cooling capacity. GlobeCore provides mobile and stationary filtration units for on-site or industrial-scale oil servicing.

Viewing 20 posts - 1 through 20 (of 66 total)

Sign up

Sign in

To continue log in with Google.