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Fuses

Precautions for Fusing Components

Anti-Surge Characteristics

  • Be careful of the short time over current (inrush current, reversible current at motor-lock etc.) that is generated in the circuit.
  • Inrush current will differ according to the ambient temperature and the charging/discharging condition of the capacitor etc. Check the current wave form with the condition which will be the maximum current.
  • When components that are highly dependent on temperatures such as thermistors are used within the circuit, check the current wave form with the condition which will be the maximum current.
  • Set the sampling frequency at a level which the peak current can be detected when measuring the surge current with a digital oscilloscope.
  • Generally, current probes are used for current measurement. When shunt resistors are used, be sure to use the lowest resistance value as possible according to the impedance in the circuit.

Operation Check

  • Before you decide which fuse product you use, please mount the selected fuse on actual device and confirm that rush current and surge current have enough margin and that the product has performance that enables to interrupt the abnormal current quickly.

Soldering

  • This product is suitable both for reflow-soldering and for flow-soldering, but an excessive heat may cause an open and change its characteristics.
  • The part shall be soldered at the maximum temperature of 260°C or less.
  • If a soldering iron is used, it shall be at 350°C or less and should be soldered in a short time. Further, pay attention that the products are not touched directly by the top of the iron. It may cause disconnection or characteristic change.

Placement

  • Please confirm sufficiently the evaluation of reliability and use those that have small contractile stress at a resin stiffening time. By contractile stress at the resin stiffening time, fuses might be broken, resistance value may be changed and disconnection might occur in case of resin coating/potting or molded sealing. There is a possibility that heat may fill the surrounding of the fuses by shielding and may cause the fusing characteristics to change so please check with the actual circuit.
  • The fusing characteristics may change when there are components that generate heat very much around the fuses. Keep fuses away from those parts.
  • Please confirm sufficiently the evaluation of reliability and use those that have small contractile stress at a resin stiffening time. By contractile stress at the resin stiffening time, fuses might be broken, resistance value may be changed and disconnection might occur in case of resin coating/potting or molded sealing. There is a possibility that heat may fill the surrounding of the fuses by shielding and may cause the fusing characteristics to change so please check with the actual circuit.
  • The fusing characteristics may change when there are components that generate heat very much around the fuses. Keep fuses away from those parts.

Storage

  • Avoid storing components under the condition of high temperature/high humidity (40°C、70% or more) which may deteriorate solderability.
  • Also avoid direct sun light which may deteriorate solderability and induce changes in taping strength.

Parts selection

  • If you have any questions about the way of selecting fuses, please do not hesitate to ask us with the information on rated voltage, operating temperature, wave-forms of steady-state current and rush current, and fusing current.

Reference

Safety Standards

  • The safety standards applicable to the fuse products are as follows.
    The certified safety standards differ to each product.
  • JAPAN PSE (Type B) PSE
    U.S.A. UL (Underwriters Laboratories Inc.)
    UL248
    CANADA CSA (Canadian Standards Association)
    C22.2 No.248
    c-UL (Underwriters Laboratories Inc.)
    UL248
    ※ c-UL is equivalent to CSA in recognition.
    UL/c-UL
    INTERNATIONAL IEC (International Electrotechnical Commission) 60127-1, -4

Rated Current

  • Current specified by us to be suitable for safety standards of fusing time, not the current stationary applicable. Stationary current of a current of a circuit can be calculated with the following equation:
  • Circuit Stationary Current≦ Rated Current Value ×Stationary Derating Coefficient

                              ×Ambient Temperature Derating Coefficient

  • Stationary Derating Coefficient
  • The table below indicates deratings for each type of products.

    Type Stationary Derating Coefficient
    CCF1N, CCF1F 0.7
    TF16AT 0.75
    TF10BN, TF16SN, TF16VN 1.0
    CCP2B, CCP2E 1.0

  • Deratings for Ambient Temperatures
  • The following Deratings for Ambient Temperatures are required:

  • Regard the peak current as stationary current when current waveform is repeated pulse or AC waveform. Do not use the effective value of the current waveform.

Rated Voltage

  • A rated voltage indicates the voltage that does not run through electrodes after the fuse blows. In case of exceeding the rated voltage, the circuit voltage should be applied at voltage not higher than the rated voltage because the current may run again or may break the elements.

Interrupting Capacity

  • An interrupted capacity indicates current and voltage that can be interrupted when an abnormal situation arises. Make sure beforehand that voltage and current at the time of abnormality occurring in the circuit are within the interrupting capacity.

Fusing Current

  • It indicates a current that interrupts a circuit. Refer to the following list to quickly interrupt an abnormal current occurred in the circuit:
  • Type Fusing Current Fusing Time
    CCF1N(0.4〜10) Rated Current ×2 or OVer 1s
    CCP2B Rated Current ×2 or Over
    CCP2E Rated Current ×2.5 or Over
    CCP2E□H Rated Current ×2 or Over
    TF16SN Rated Current ×2 or Over
    TF10BN Rated Current ×2 or Over 5s
    TF16AT Rated Current ×2 or Over
    TF16VN Rated Current ×2.5 or Over
    CCF1N(12, 15) Rated Current ×2 or Over 60s
    CCF1F Rated Current ×2 or Over 120s

    If its fusing time is within 1 second, the variance in the fusing time affected by the surroundings (temperature, mounting pad dimensions, substrate material, etc.) will be negligible. But if it is not less than 1 second, it will be largely affected by them, so its verification should be made with an actual circuit.

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