ÒZNR
â
Ó
Transient/Surge Absorbers, Type E, Type CK
ÒZNR
â
Ó Transient/Surge Absorbers, Type E
ÒZNR
â
Ó Transient/Surge Absorbers, Type CK
Handling Precautions
1.
Safety Precautions
ÒZNRÓ Transient/Surge Absorbers (hereafter referred to as ÒZNR VaristorsÓ) may fail in either a short or open-
circuit mode when subjected to severe conditions of electrical, environmental and/or mechanical stresses
(beyond their specified ÒRatingsÓ and ÒConditionsÓ). Worst case failure may result in glowing, flaming or
burnout.
The following Ò Safety PrecautionsÓ and ÒApplication NotesÓ should be taken into major consideration. For
further questions regarding the ÒHandling PrecautionsÓ, please contact our engineering section or factory.
1.1
Operating Conditions
1.1.1
ZNR Varistors should not be operated beyond
1.1. 3
When ZNR Varistors are used between a live
their specified ÒRatingsÓ or ÒEnvironmental
part and a electrically conductive chassis, follow
ConditionsÓ in the Catalog or the Specifications to
safety countermeasures to avoid electric shock.
A) The metallic chassis should be grounded.
prevent them from deterioration, breakdown, flaming
B) The live part should be have a protected
or glowing.
cover to prevent contact and potential electric
l
ZNR Varistors should not be operated exceeding
their specified ÒMaximum Allowable VoltageÓ.
shock.
l
ZNR Varistors should not be subjected to
2. Application Notes
energy levels above their specified ÒMaximum
2.1 Usage Precautions
Energy RatingsÓ.
2.1.1
ZNR Varistors should be protected from
l
In case of exposure to repeated surge/
accidental failure by following the cautionary
overvoltage, the ZNR Varistors should not be
notes:
subjected to surge currents and energy levels
l
In case of ÒAcross-the Line UseÓ, ZNR
above the specified maximum ratings in the ÒImpulse
Varistors should be protected by connecting
Life RatingÓ section or Individual Specifications.
a fuse in series to the devices. (See Table 1)
l
When surge/overvoltages are intermittently
l
In case of ÒLine to Ground UseÓ, a short-circuit
applied to ZNR Varistors in short durations, the
condition of the Varistor may not blow the current
devices should not be operated beyond their
type fuse due to the grounding resistance (be-
specified ÒRated PowerÓ.
tween Line and Ground), and may cause flaming
l
ZNR Varistors should not be operated beyond
or burnout of the device. (in the worst case)
their specified ÒOperating Temperature RangeÓ.
l
It is recommended that ZNR Varistors, if not
The following safety countermeasures (A or B)
fused, should be mounted away from other
are therefore recommended;
combustible components.
A) Connect a Òleakage current circuit breakerÓ in
1.1.2
ZNR Varistor must be operated correctly
series to the Varistor to be protected. (See Table 1)
under the following conditions to prevent
B) Use current type fuses and a thermal type fuse
mechanical damages and ruptures and to
thermally coupled each other. (See Table 1)
avoid serious injuries;
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ZNR Varistors should not be operated in
excess of their specified ÒMaximum Allowable
Voltage RatingÓ.
l
ZNR Varistors should not be operated beyond
their ÒMaximum Peak Current RatingsÓ.
l
Some safety countermeasures such as a
protective case covering the Varistor are
recommended; If additonal safety is required for
the application.
Rev.02/04
ÒZNR
â
Ó
Transient/Surge Absorbers, Type E, Type CK
2.2 Circuit Design 1
(Selection of Varistor Voltage Rating)
2.2.1 General Precautions
In the selection of Varistor Voltage Ratings for line
protection, the following general precautions
should be taken into consideration;
(1)Maximum operating voltage must be lower than
the specified ÒMaximum Allowable VoltageÓ.
(2)Some reasonable margin is required against
fluctuation of the primary AC line Voltage where
the Varistor is used to prevent mechanical
and/or electrical failure of the device.
2.2.2 Across-the-Line Use
(Line to Line surge protection)
l
Select ZNR Varistors recommended in Table 1.
Notes:
Because the primary line voltage temporarily
rises due to load unbalance of separated
wired loads, short circuit between the live line
and the neutral line or LC resonance at switch-
ing for a capacitive load, ZNR Varistors with
]
are recommended for AC120 V or 240 V
applications. (See Table 1)
2.2.3 Line to Ground Use
(Line to Ground Surge protection)
l
Select the ZNR Varistors recommended in Table 1.
Notes:
When 500 V insulation resistance test of the
circuits employing ZNR Varistor is conducted,
ZNR Varistor should be removed after
getting approval from the customer, or the
ZNR Varistor
] ]
with the Maximum Allowable
Voltage exceeding the test voltage should be
applied. (See Table 1)
When AC1000 V or 1200 V dielectric with
standing test is conducted, ZNR Varistors
should be removed after getting approval from
the customer according to the relevant
regulations, or ZNR Varistor
] ] ]
(See Table 1)
2.4 Environmental Conditions
(1)ZNR Varistors are designed for indoors use only.
(2)ZNR Varistors should not be exposed to direct
sunlight and heat ing part of equipment.
(3)ZNR Varistors should not be operated under
severe conditions of high temperature and/or high
humidity such as places exposed to rain, wind
and water condensation.
(4)ZNR Varistors should not be exposed to dusty
environments or atmospheres of salt water or
corrosive gas.
2.5 Precautions for Assemblies and Handlings
2.5.1 Solvent Cleaning
Organic solvents such as thinner, acetone, etc.
should not be applied to the ZNR Varistors to
prevent deterioration of the external coating or
molding resin.
2.5.2 Abnormal Mechanical Stresses
Abnormal mechanical stresses beyond the specified
values (such as excessive shocks, vibrations and
bending/pulling forces) should be kept to a
minimum prevent mechanical/electrical failures of the
devices.
2.5.3 Plastic Molding
If an optional plastic molding is applied to ZNR
Varistors, the effects on reliability of ZNR Varistors
should be carefully investigated.
2.6 Long Term Storage
(1)ZNR Varistors should not be stored under
severe conditions of high temperature and/or high
humidity. Store them indoors under 40 ¡C max.
and 75 %RH max. Store and use them within
one year of manufacture date. Check the
solderability before use.
(2)ZNR Varistors should not be stored under
corrosive atomospheres such as hydrogen
sulfide, sulfuric acid, chlorine, and ammonia.
(3)ZNR Varistors should not be exposed to direct
sunlight and shouldnot be stored under high water
condensation.
2.3 Circuit Design 2 (Fusing Varistors)
2.3.1
When a line current of equipment is higher than
the recommended current rating of the fuse in
Table 2, the location of the fuse should be arranged
as shown in Fig 2.
2.7 Regarding to
ÒSafety
Regulations of the
VaristorsÓ
In case of applications to UL and CSA, refer to
the ÒApplication Notes for UL and CSA Recog-
nizedÓ ZNR ÒVaristorsÓ
2.8 Parallel Capacitances of ZNR Varistors
ZNR Varistors have relatively high capacitances
specified in the Individual specifications, special
consideration should be taken into account
in applications to high frequency transmission
lines or circuits.
Fig. 2 Alternative Fuse Location/placement
for Varistor Protection
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