Handling of Products

Operating Instructions

Thank you for purchasing Hirai's transformers.
Please read and understand "PRECAUTIONS" and "HANDLING OF OUR PRODUCTS" without fail before use to handle products in safety and in the right way.


  1. Person who has sufficient knowledge and skill is to handle product to use safely.
  2. Please read all instruction manuals and other attached documents before use for proper handling. Please use products after familiarized with all knowledge of products, information of safety, and precautions. Please give users easy access to these manuals and documents stored on where users can confirm any time after completed reading.
  3. DO NOT take following actions:  * Operations and handling not described in instruction manuals.  * Use and modification of non-specified replacement parts.
  4. 4. Classes of safety precaution are indicated in 2 classes as "DANGER" and "WARNING" in instruction manuals.

However, topics in "WARNING " may cause serious accident by circumstances.
Please keep these instructions, described important contents, for certain.


General notice
  1. Danger of electric shock. Never work (connect/installation etc.) during live-line.
  2. Danger of electric shock. Never open secondary circuit of transformer.
  3. Danger of electric shock. Must connect primary earthing terminal of earthing voltage transformer to ground.
General notice

Danger of electric shock. Never touch live part.(mold surface including bushing)

Notice for maintenance and inspection
  1. Danger of electric shock and injury. Person who possesses knowledge and technique must do maintenance and inspection.
  2. Danger of electric shock. Must disconnect live part (mold surface including bushing) and connect main circuit terminal to ground for maintenance and inspection.


Notice for acceptance and unpacking
  1. Danger of injury by falling/tumble. Do not lay down/turn over.
  2. Danger of injury and fire. Do not use damaged products.
Notice for transportation

Danger of injury by falling/tumble. Do not transport by non-specified method.

Notice for installation
  1. Danger of injury and fire. Do not work by non-specified installation.
  2. Danger of fire etc. Do not use by non-specified method.
  3. Danger of injury, fire, and burn injury. Never short secondary circuit of voltage transformers.
Notice for maintenance and inspection

Danger of fire, etc. Do not use equipments with abnormality/damage.

Notice for disposal

Dispose our products as industrial waste.

Handling of Our Products

  1. Installation site Use condition of our transformers is "standard use condition"defined in Standards. Please confirm that installation environment is appropriate to use condition before installation.

Below is abstract from section 3, JIS C 1731, issued by Japanese Standards Association.

Standard condition for use

  1. Ambient temperature : between - 20℃ and 40℃. (average temperature: less than 35℃)
  2. Altitude : less than 1000m.
  3. Place does NOT conform "special condition" as below.

Special condition for use

  1. Places where exposed by sea breeze, rain, snow, and sunlight.
  2. Places where moistness, excessive water vapor, and dew may occur.
  3. Places where oil vapor, explosive fumes, flammable gas, hazardous gas, and corrosive gas occur.
  4. Places where excessive foreign matter and dust exist.
  5. Places where abnormal vibration and shock may happen.
  6. Use under other special conditions.

 * Please confirm us when your installation place is "special condition for use.

  1. How to install
    1. Do not apply load of cable/bus bar etc. on products when installation.
    2. Separate primary lead wire and bus bar, except connecting terminals, from mold surface to avoid corona occurrence.
    3. Connect secondary lead wire to terminal correctly. Do not get close to mold surface.
    4. Work wire connection accurately according to terminal marks, wire drawing on name plate etc.
    5. Connect terminal of primary grounding side of earthing voltage transformer to ground surely.
    6. Connect terminal of secondary grounding side and frame for installation of main unit to ground surely.
    7. Tighten up bolts and nuts to fasten cable bus-bar and lead wire etc. for sure.
    8. For wire size, use appropriate material and wire diameter for circuit voltage and rated current.
    9. Use appropriate wire size for crimping terminal. Use of inappropriate wire size will cause burnout and fire.
  2. Maintenance/inspection Maintenance and inspection are necessary to operate transformer safely and to prevent accident from occurring. It is recommended to operate maintenance and inspection based on JEM-TR 164 "Guideline for maintenance and inspection of transformer", issued by The Japan Electrical Manufacturer's Association(JEMA).
    1. To have daily check minimum of 1time/month is recommended to detect abnormal sound, abnormal odor, abnormal noise, abnormal overheat, corrosion, and undue defacement.
    2. Cut power 1time/year at least, inspect regularly and mainly current-carrying part where daily checking can not cover. Confirm no abnormality of apparent condition/looseness of iron core, screws, bolts etc. Clean up surface with dry cloth before insulation performance evaluation by insulation resistance measurement.
  3. Recommended renewal period of products Recommended renewal period is determined in "Guideline for maintenance and inspection of transformer", JEM-TR 164, issued by The Japan Electrical Manufacturers' Association(JEMA). We recommend to renew based on this guide line. Below recommended renewal period is premised on having daily and periodical checks.

Recommended renewal period of transformers (use of years)
Mold type (include outer dry type) : 15years

Above number is NOT guaranteed value of products.

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