Panasonic ZNR TYPE E User manual

“ZNR” Transient/Surge Absorbors, Type E, Type CK, SC
– 54 –
1. Precautions for Safety
The “ZNR” Transient/Surge Absorbers (hereafter referred to as “The ZNR Varistors”) may fail in a short-circuit mode
or in an open-circuit mode, when subjected to severe conditions of electrical, environmental and/or mechanical
stresses beyond their specified “Ratings” and specified “Conditions”, resulting in burnout, flaming or glowing in the
worst case.
Following “ Precautions for Safety” and “Application Notes” shall be taken in your major consideration. If you have
a question about the “Precautions for Handling”, please contact our engineering section or factory.
Handling Precautions
“ZNR” Transient/Surge Absorbers, Type E
“ZNR” Transient/Surge Absorbers, Type CK, SC
1.1 Operating Conditions
1.1.1 The ZNR Varistors shall not be operated beyond
the specified “Ratings” and “Environmental
Conditions” in the Catalog or the Specifications to
prevent them from deterioration, breakdown, flaming
or glowing.
●The ZNR Varistors shall not be operated exceeding
the specified “Maximum Allowable Voltage” in the
Catalog or the Specification.
●The ZNR Varistors shall not be subjected to
energy levels above their specified “Maximum
Energy Ratings” in the Catalog or the Specifications.
●In case of application to repeated surge/
overvoltages, the ZNR Varistors shall not be
subjected to surge currents and energy levels
above the specified maximum ratings in “Impulse
Life Rating” in the Catalog or the Specifications.
●When surge/overvoltages are intermittently
applied to the ZNR Varistors with short durations,
the devices shall not be operated beyond the
specified “Rated Power” in the Catalog or the
Specifications.
●The ZNR Varistors shall not be operated beyond
the specified “Operating Temperature Range” in
the Catalog or the Specifications.
●It is recommended that the ZNR Varistors, if
not fused, shall be located away from other
combustible components.
1.1.2 The ZNR Varistor shall be operated correctly
under following conditions to prevent Varistors from
causing mechanical damages and ruptures and to
protect human from serious injuries;
●The ZNR Varistors shall not be operated
exceeding the specified “Maximum Allowable
Voltage Ratings” in the Catalog.
●The ZNR Varistors shall not be operated beyond
the “Maximum Peak Current Ratings” in the
Catalog.
●Some safety countermeasure such as a
protective case covering the Varistor is
recommended, if necessary.
1.1.3 When the ZNR Varistors are applied to between
a live part and a metallic chassis of equipment,
following safety countermeasures shall be taken to
protect human from electric shock.
A) The metallic chassis shall be earthed to the
ground.
B) The live part shall be equipped with a protective
cover for preventing electric shock.
2. Application Notes
2.1 Protective Devices for Varistors
2.1.1 The ZNR Varistors shall be protected from serious
accidents due to unexpected physical phenomenor
by following safety countermeasures.
●In case of “Across-the Line Use”, the ZNR
Varistors shall be protected by connecting a
ground fault circuit interrupter of fusing in series
to the devices. (See Table 1)
●In case of “Line to Ground Use”, the short-circuit
of the Varistor may not blow the current type fuse
due to the grounding resistance (between Line
and Ground), which may cause flaming or burn-
out of the devices in the worst case.
Following safety countermeasures (A or B) are
recommended;
A) Connecting a “leakage current circuit breaker” in
series to the Varistor to be protected. (See Table
1)
B) Use current type fuses and a thermal type fuse
which are thermally coupled each others. (See
Table 1)
✽Fuses shall use rated voltages appropriate for circuits.
✽Finally, confirm that the secondary disaster does not
occur even if the ZNR mounted on equipment breaks.
✽Set a thermal fuse to get high thermal conductivity
with ZNR.
Series ERZC20EK□□□ ERZC32□K□□□ ERZVS34C□□□
ERZC40CK□□□
Current Fuse
(Line - Line)
10 A max. 20 A max. 20 A max.
Thermal. Fuse
(Line - Ground)
100 to 120 °C 5 A 100 to 120 °C 10 A 100 to 120 °C 10 A
● Recommendation fuse
Aug. 201201

“ZNR” Transient/Surge Absorbors, Type E, Type CK, SC
– 55 –
Fuse
ZNR
Varistor
Protected
Equipment
2.2 Circuit Design 1
(Selection of Varistor Voltage Rating)
2.2.1 General Precautions
In selection of Varistor Voltage Ratings for line
protection, following general precautions shall be
taken in your consideration;
(1) Maximum operating voltage shall be lower than
the specified “Maximum Allowable Voltage” of the
Varistor applied.
(2)Some reasonable margin is required against
fluctuation of the primary AC line Voltage where
the Varistor is applied for preventing mechanical
and/or electrical failures of the device.
2.2.2 Across-the-Line Use
(Line to Line surge protection)
●Select the ZNR Varistors recommended in Table 1.
Notes: Because the primary line voltage temporarily
rises due to load unbalance of separately
wired loads, short circuit between the live line
and the nutral line or LC resonance at switching
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)
●Select the ZNR Varistors recommended in Table 1.
Notes: When 500 V insulation resistance test of the
circuits employing ZNR Varistor is conducted,
the ZNR Varistor shall be removed after
getting approval from the customer, or the
ZNR Varistor ✽✽with the Maximum Allowable
Voltage exceeding to the test voltage shall be
applied. (See Table 1)
When AC1000 V or 1200 V dielectric with
standing test is conducted, ZNR Varistors
shall be removed after getting approval
from the customer according to the relevant
regulations, or ZNR Varistor ✽✽✽with the
Maximum Allowable Voltage exceeding to the
test voltage shall be applied. (See Table 1)
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 shall be arranged
according to Fig 2.
Fig. 2 Alternative Fuse Location/placement
for Varistor Protection
2.4 Environmental Conditions
(1) The ZNR Varistors shall not be exposed
outdoors, because of being designed for indoors
use.
(2)The ZNR Varistors shall not be operated beyond
the Specified Operating Temperature Range and
shall not be exposed to direct sunlight and heating
part of equipment.
(3)The ZNR Varistors shall not be operated under
severe conditions of high temperatures and high
humidities such as places exposed to rain, wind
and vapor.
(4) The ZNR Varistors shall be free from dust, salty
wind and atomospheres polluted by corrosive
gas.
2.5 Precautions for Assemblies and Handlings
2.5.1 Solvent Cleaning
Organic solvents such as thinner and acetone
etc. shall not be applied to the ZNR Varistors for
preventing deterioration of the external coating or
molding resin.
2.5.2 Abnormal Mechanical Stresses
Abnormal mechanical stresses beyond the specifi e d
values such as strong falling shocks, ribrations and
bending/pulling forces, shall be kept minimum to
preventmechanical/electrical
failures of the devices.
2.5.3 Plastic Molding
If another plastic molding is applied to the ZNR
Varistors on your option, the influences on reliability
of the ZNR Varistors shall be carefully investigated
in your equipment.
2.6 Long Term Storage
(1)The ZNR Varistors shall not be stored under
severe conditions of high temperatures and high
humidities. Store them indoors under 40 °C max.
and 75 %RH max. Use them within one year, if
stored beyond the limit, check the solderbility before
use.
(2)The ZNR Varistors shall not be stored under
corrosive atomospheres such as hydrogen
sulfide, sulfurous acid, chlorine and ammonia.
(3)The ZNR Varistors shall not be exposed to direct
sunlight and shall not be stored under dew
formation.
2.7 Regarding to “Safety Regulations of the
Varistors”
In case of applications to UL and CSA standards,
refer to “Application Notes for UL and CSA Recognized”
ZNR “Varistors”
2.8 Parallel Capacitances of the ZNR Varistors
The ZNR Varistors have relatively high capacitances
specified in the individual specifications, special
consideration shall be taken into account in
applications to high frequency transmission
lines or circuits.
Aug. 201201

“ZNR” Transient/Surge Absorbors, Type E, Type CK, SC
– 56 –
f ZNR1
Protected
Equipment
f
ZNR1 Protected
Equipment
ZNR2
Thermal. Fuse
Thermal
coupling
f ZNR3
Protected
Equipment
f ZNR3
Protected
Equipment
ZNR4
Thermal. Fuse
Thermal
coupling
f
f
Table 1. Application Examples
Connections
Across-the-Line/Line to Line Protection Line to Line and Line to Ground Protection
D.C.
A.C. Single phase
D.C.
A.C. Single phase
A.C. 3 phase A.C. 3 phase
Selection Examples
Across the Line Use/Line to Line Line to Ground Use
ZNR Nominal
Line Voltage
Part Number of ZNR ZNR Nominal
Line Voltage
Part Number of ZNR
Type E, CK, SC Type E, CK, SC
ZNR1
ZNR3
AC 100 V
ERZC□□EK
ERZC□□CK
ERZVS34C
201
241
271
ZNR2
ZNR4
AC 100 V
to AC 220 V ERZC□□EK
ERZC□□CK
ERZVS34C
471
511
821 ✽✽
AC 120 V 241
271 ✽
AC 200 V
to AC 220 V 471
AC 240 V 511
821 ✽✽
AC 240 V 511
f : fuse
f : fuse
f : fuse
f : fuse
Aug. 201201