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Matters to Be Observed When Using This Product
Safety measures
An abnormal state for varistors (ZNR surge absorbers) of the D type/V series and SMD-Type/HF, VF Series (hereinafter
the product or "the surge absorber") that results from a problem with service conditions (materials used, the surrounding
environment, power conditions, circuit conditions, etc.) may cause a fire accident, electric shock accident, burn accident,
or product failure. Matters to note when handling this product will hereinafter be described. What is described below should
be checked sufficiently before the product is used.
■ Confirming rated capabilities
Use the surge absorber within the range of its rated capabilities. Each type of surge absorber has specified rated
capabilities including a maximum allowable circuit voltage, a surge current tolerance, an energy tolerance, an impulse
lifespan (surge lifespan), average pulse power, and a service temperature. Using the surge absorber under severe
service conditions that are beyond the rated capabilities causes degraded performance of the surge absorber or
destruction of a circuit element, which may lead to smoke generation, ignition, etc.
■ Take the following measures in order to avoid an accident caused by expected phenomenon.
(1) Destruction of the surge absorber may scatter its fractured pieces around. To protect other elements from these
pieces, set product in a case or shield it with a cover.
(2) Do not place the surge absorber near combustible materials (vinyl cable, resin mold, etc.). If avoiding the vicinity
of combustible materials is difficult, protect the combustible material with an incombustible cover.
(3) Surge absorber placed between lines
When the surge absorber is placed between lines, connect a normal type current fuse in series with the surge
absorber.
* See "Current fuse" in the "Circuit design and circuit board design" section.
(4) Surge absorber placed between a line and the ground
① When the surge absorber is placed between a line and the ground, even if the surge absorber short-circuits,
ground resistance will remain in the section between the line and the ground, leaving a possibility that the
current fuse won't blow, in which case the outer sheath resin of the surge absorber may generate smoke or
ignite due to current flow. To prevent such a case, place an earth leakage breaker in a location closer to the
power supply than the surge absorber. When not using an earth leakage breaker, use a current fuse and
temperature fuse in series with each other.
* See Table 1 in the "Circuit design and circuit board design" section.
② When the surge absorber is placed between a live part and a metal case, it may cause electric shock if the
surge absorber short-circuits. To avoid this, ground the metal case or shield it to prevent direct contact with the
metal case.
■ In case the surge absorber should short-circuit and generate smoke or ignite, immediately cut off current flow
to the surge absorber.
■ Rated voltage for UL certification, etc.
To allow the surge absorber to meet leak current requirements, etc., a maximum allowable circuit voltage and rated
voltage are specified for the surge absorber.
When applying for UL certification, etc. of a device equipped with a surge absorber, ensure the working voltage of the
device does not exceed the rated voltage of the surge absorber.
■ An unexpected sharp rise in the working voltage, an incoming excessive surge, etc., may cause the surge absorber to
generate smoke or ignite.
In such a case, fire spreading through the device should be prevented to avoid expanded damage. To achieve this,
take a multi-protection measure, such as adopting fire-resistant materials that make up the outer shell components
and structural materials.
(D-type : V series / SMD-type : HF・VF series)
Matters to Be Observed When Using This Product
30-Jun-23
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