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    7 kVA Isolation Transformer, 3 phase, 380V to 208V

    5 out of 5 based on 2 reviews | Write a review
    7 kVA isolation transformer is a step up or step down transformer in low cost, 3 phase, convert primary voltage 380V to secondary voltage 208V, better dielectric strength and insulation resistance.
    30-day Returns
    Delivery date: 10-20 days

    ATOSG-7KVA isolation transformer is a three phase unit with 7 kVA rating and primary voltage of 380V AC on the primary side. This transformer has a secondary voltage of 208V AC on the secondary side. It is designed for use in control circuits and general applications such as mechanical and electronic equipment, precision machine tool, CNC machine tool, lighting, etc.

    7 kVA Isolation Transformer Specifications

    Basics Model ATO-SG7KVA
    Phase 3 phase
    Capacity 7 kVA
    Weight of Aluminium Wire Transformer Open type: 65kg
    Protected type: 81kg
    Weight of Copper Wire Transformer Open type: 58kg
    Protected type: 71kg
    Technical Parameters Primary Voltage 380V (Optional: 120V/ 190V/ 208V/ 220V/ 230V/ 240V/ 380V/ 400V/ 415V/ 480V)
    Secondary Voltage 208V (Optional: 120V/ 190V/ 208V/ 220V/ 230V/ 240V/ 380V/ 400V/ 415V/ 480V)
    Frequency 50Hz / 60 Hz
    Winding Material Aluminium/Copper wire (Optional)
    Work Efficiency ≥95%
    Insulation Resistance ≥50 MΩ
    Electrical Strength 3000V AC/1 min
    Noise <35-65dB (1 meter)
    Insulation Grade H level
    Wiring Mode Dyn11
    Cooling Mode Dry type air cooling
    Overload Capacity Allow more than 1.2 times rated load to work for up to 4 hours
    Enclosure Protection Grade IP 24
    Certificate CE, ISO
    Warranty 12 months
    Working Environment Temperature -15℃~+40℃
    Humidity ≤90%RH, without condensation
    Altitude <1000m, non corrosive gas and conductive dust


    Transformer can only convert voltage and CANNOT convert frequency.
    Transformer CANNOT convert single phase voltage to 3 phase voltage.
    Input/output voltage, power rating and whether with shell of all transformers, can be customized according to clients' requirements.

    3 Phase Isolation Transformer Schematic Diagram

    ATO isolation transformers schematic diagram

    3 Phase Isolation Transformer Details

    3-phase isolation transformer details

    7 kVA Isolation Transformer Installation Dimension

    3 phase isolation transformer dimension

    Aluminium Wire Transformer Size Copper Wire Transformer Size
    Open type: a*b*c=380*220*380mm Open type: a*b*c=300*170*310mm
    Mouting size: d*e=260*130mm Mouting size: d*e=180*140mm
    Protected type: A*B*C=380*530*560mm Protected type: A*B*C=300*440*500mm

    Tips: What circumstance the isolation transformer must stop running?

    ATO step up/down isolation transformer should be stopped immediately if one of the following situations occurs:

    1. Noise inside the isolation transformer is very large, very abnormal and has crackle sound.
    2. Under normal load and cooling conditions, the upper oil temperature of the transformer is abnormal and keeps rising.
    3. Expansion tank occurs or explosion-proof tube injects fuel.
    4. Serious oil leakage occurs, resulting in the oil level lower than the oil level indicator limit.
    5. Oil color changes too much, there is carbon in the oil.
    6. Casing has serious damage and electric discharge phenomena.
    7. Isolation transformer catches fire.
    8. Casing connector and lead turns red, melted or fused.

    How to Test Step Up & Step Down Isolation Transformer?

    Need more detail of ATO isolation transformer? Here is a good explanation about it in this video. To test the accuracy of the transformer voltage, we take a 3000 VA single phase 220V iuput to 110V output isolation transformer as an example.

    Existing reviews of 7 kVA Isolation Transformer, 3 phase, 380V to 208V
    Why is the votage between two hot of isolation transformer 400V?
    Attached is a photo of the nameplate. Below is a photo of the field wiring listed inside the transformer.
    On the low side there are three hot wires and one neutral. The measured voltages match the diagram that I provided. Between neutral and any of the hot is 230V, but between two hot it is 400V.
    From: duran | Date: 10/05/2023
    Was this review helpful? Yes No (0/0)
    ATO Responded
    According to the nameplate of the transformer you provided, we believe that the voltage between the two live wires is 230V.
    Regarding the "between two hot it is 400V" you mentioned, please provide us with your measurement video or picture for further confirmation.
    You can send us the large video file via we Thank you for your understanding.
    What is your isolation transformer input voltage tolerance?
    I need a step down isolation transformer and this 7kVA capacity unit is what I am looking for. I want to know what is your isolation transformer input voltage tolerance?
    From: Farman Pannah | Date: 29/12/2019
    Was this review helpful? Yes No (0/0)
    ATO Responded
    The transformer input voltage tolerance is +/- 5%.
    The manufacture made the tolerance 5% Not 10%, just to keep transformer output voltage around required standard secondary voltage. As you know for transformers, the output voltage is changed automatically with the input voltage change.
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