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Products » Epcos and TDK protection devices » Epcos varistors »

Epcos varistors

TDK-EPC Varistors

Varistors (variable resistors) are voltage-dependent resistors with a symmetrical V/I characteristic curve which resistance decreases with increasing voltage. Connected in parallel with the electronic device or circuit that is to be guarded, they form a low-resistance shunt when voltage increases and thus prevent any further rise in the surge overvoltage. The most common type of varistor is the metal-oxide varistor (MOV).

Sintering Zinc oxide together with other metal oxide additives under specific conditions produces a polycristalline ceramic whose resistance exhibits a pronounced dependence on voltage. This phenomenon is called the varistor effect.TDK-EPC Varistors The figure shows the conduction mechanism in a varistor element in simplified form. The zinc oxide grains themselves are highly conductive, while the intergranular boundary formed of other oxide is highly resistive. Only at those points where zinc oxide grains meet does sintering produce "microvaristors", comparable to symmetrical zener diodes (protection level approx. 3.5V). The electrical behaviour of the metal oxide varistor, as indicated by figure, results from the number of microvaristors connected.
The series and parallel connection of the individual microvaristors in the sintered body of a SIOV also explains its high electrical load capacity compared to semiconductors. While the power in semiconductors is dissipated almost entirely in one thin p-n junction area, in a SIOV it is distributed all over the microvaristors, i.e. uniformly throughout the component's volume. Each microvaristor is provided with energy absorbers in the form of zinc oxide grains with optimum thermal contact. This permits high absorption of energy and thus exceptionally high surge current handling capability.
TDK-EPCOS varistors a re wildely applied in industrial equipment and home plliance:
  • For protection of semiconductor devices: thyristors, bidirectional thyristors, transistors, diodes, stabilitrons;
  • For input protection;
  • For protection of electromagnetic splashing in power inductive elements;
Typical value of varistor's operation time at voltage overload is up to 25 ns. But for protection of some equipment types this value is unsufficient (for electrostatic protection the operating time must be no more than 1 ns). In such a way the improving of varistors production technology is directed on increasing of their response rete. For example, thanks to wide application of varistors wth multilayer structure( SIOV-CN and SMD-performance) “TDK-Epcos” created components with operating time less than 0,5 ns.In disk varistors the operating time is increased up to a few nanoseconds. .
Such important characteristics as high reliability, perfect electrical features in a wide temperature range and small sizes are the main advantages of Epcos varistors.

Main varistors characteristics:

VRMS - AC operating voltage; root-mean-square value

VDC -DC opearating voltage;

Imax - Maximum surge current (also termed peak current) ;

Wmax - Maximum energy absorption;

Pmax - Maximum average power dissipation;

Vv - Varistor voltage

Vc,max - Maximum clamping voltage at specified current ic.

ic -Current at which Vc,maxis measured

Ctyp - Typical capacitance.

EPCOS varistors

Leaded varistors


EPCOS Leaded varistors are applied in devices requiring large energy dissipation. They are been produced with a compact case covered by epoxy resin. Leads are made of tinned copper wire that provides qualitative and easy mounting at the Circuit Board.

Fields of application:

Leaded varistors
  • Industrial equipment;
  • Power supplies;
  • Fotoelectrical devices;
  • Home electronics;
  • Telecommunications;
  • Inverters
Detailed information
Type Size, mm Imax(8/20µs), А Vrms, V VDC, V Wmax, J twork, ns Documentation
Series S05 - S20
Standard series of veristors
S05K11

S20K95
5 mm
7 mm
10mm
14 мм
20 mm
< 800
< 1750
< 3500
< 6000
< 12000
11…1100 14…1465 до 410 < 25 Далее
Тelecommunications
S07S60AGS2
S07S95AGS2
7 mm 1200 60
95
85
125
4.8
7.6
<25 Далее
Advanced series of varistors
S05K130E2

S20K680E2
5 mm
7 mm
10 mm
14 мм
20 мм
800

10000
130

680
170

895
6

440
< 25 Далее
Series S25
S25K130E4R12

S25K750E4R12
25 mm 20000 130

750
170

1060
75

380
< 25 Далее
Series Q14, Q20
Q14K130

Q20K460
14 мм
20 мм
8000

15000
130

460
170

615
185

1025
< 25 Далее

Leaded varistors series S-AUTO

Series of leaded varistors created specially for application in varistors created especially for application in automobile electronics. They are suitable for operating at voltage 16…48 V and working temperature up to plus125°C.

Fields of application: S-Auto
  • autoelectronics;
  • motor run
Detailed information
Type Size, mm Imax(8/20µs), А Vrms, V VDC, V Wmax, J twork, ns Detailed information
For automobile systems 12 V
S07K14AUTOS2D1
S10K14AUTO
S10K14AUTOS5D1
S14K14AUTO
S14K14AUTOS5D1
S20K14AUTO
S10K17AUTO
S14K17AUTO
S20K17AUTO
7 mm
7 mm
7 mm
7 мм
7 mm
7 mm
10 mm
10 mm
10 mm
250
500
500
1000
1000
2000
500
1000
2000
14…17 16…20 0.9
2.0
2.0
4.0
4.0
12.0
2.5
5.0
14.0
< 25 Далее
For automobile systems 24 V
S20K25AUTO
S14K30AUTO
S20K30AUTO
14 mm
14 mm
20 mm
2000
1000
2000
25
30
30
28
34
34
22.0
9.0
26.0
< 25 Далее
For automobile systems 42 V
S07V42AUTOS2D1
S10V42AUTOS5D1
S14V42AUTOS5D1
S20V42AUTOS5D1
7 mm
10 mm
14 mm
20 mm
48 3.0
6.4
13.0
37.0
< 25

SMD varistors

Series of varistors designed especially for automated line using SMT-technology. Electroctechnical characteristics are equivalent of EPCOS SIOV S05-S07.
SMD_varistor
Fields of application:
  • power supplies;
  • fotoelectrical devices;
  • home appliance;
  • mobile devices;
  • telecommunications.
Detailed information
Type Size, mm Imax(8/20µs), А Vrms, V VDC, V Wmax, J twork, ns Detailed information
CU3225K115G2

CU4032K95G2
3225
4032
100

1200
11

200
14

385
300

23000
< 25 Далее
CU3225K14AUTOG2

CU4032K30AUTOG2
3225
4032
100

250
14

30
16

34
400

2000
< 25 Далее
CU4032K480G2 4032 1000 480 640 40 < 25 Далее
CU4032S60AG2

CU4032S95AG2
4032 45 60…95 85…125 4800…7600 < 25 Далее

Block varistors

Varistors in hermetic package with screw terminals. Such construction makes the mounting easier.
Block type varistors
Fields of application:
  • industrial equipment;
  • power supplies;
  • fotoelectrical devices;
  • wind machines;
  • inverters.
Detailed information
Type H×W×, Dmm Imax(8/20мкс), А Vrms, V VDC, V Wmax, J twork, ns Detailed informatoin
B32/ B40
B60
B80
55×40×14
100×100×24
100×135×27
25000

100000
75… 1100 100 … 1465 190 … 6000 < 25 Далее

Housed (ThermoFuse) varistors

EPCOS disk varistors inspecial plastic case. They unite all advantages of TDK-EPCOS leaded varistors and also provide a perfect protection of circuits due to a fuze.

Fields of application: ETFV
  • Industrial equipment;
  • POwer supplies;
  • Power meters;
  • Inverters.
Detailed information
Тип H×W××D, mm Imax(8/20µs), А Vrms, V VDC, v Wmax, J twork, ns Detailed information
ETFV14
ETFV14K130E2

ETFV14K420E2
22×19.2×11.2 6000 130

420
170

560
50

136
< 25 Далее
ETFV20
ETFV20K130E2

ETFV20K420E2
25.7×22×9.7 10000 130

420
170

560
100

273
< 25 Далее
ETFV25
ETFV25K115E4

ETFV25K420E4
115×22×9.7 20000 115

420
150

560
170

700
< 25 Далее

Energy Varistors SIOV-E

SIOV metal oxide varistors in the E series are designed to be used as active elements in gapless surge arresters for protection of medium and high voltage AC power utility distribution systems against overvoltages. Glass collar passivation makes this series suitable for a broad range of arrester designs such as porcelain housed arresters, or polymer housed arresters with a hollow insulator as well as for molded polymer arresters. The broad range of diameters supports the different class requirements according IEC and ANSI. E32_E41

Fields of application:
  • Arrester blocks for distribution class
  • Arrester blocks for station class
Detailed information
Type D×h, mm Vrms, kV Vov, kV Imax
(8/20µs), кА
Imax
(4/10µs), кА
Imax
(2 ms), А
Pmax, W Detailed information
E 32
E32VR302S 32×17.7 2 2,45 5 65 150 0,18 Далее
E32VR502S 32×29.6 5 4,1 5 65 150 0,3 Далее
E32VR602S 32×39.5 6 4,9 5 65 150 0,35 Далее
E 41
E41NR302S 41.9×19.5 3 2.45 10 100 400 0.27 Далее
E41NR502S 41.9×29.4 5 4,1 10 100 400 0.45 Далее
E41NR602S 41.9×41 6 4,9 10 100 325 0.5 Далее

Strap varistors

This series of EPCOS is created for application in circuits with large current capability. They withstand maximal discharging current from 40 кА ( LS40) to 75 кА ( LS50). features of construction: Bolt-holed strap terminals for screw fixing or soldering, Bent or straight strap terminals.
E32_E41
fields of application:
  • Power supplies;
  • Fotoelectronic converters;
  • Wind-powered generator;
  • The protection form voltage overload.
Detailed information
Type H×W××D, mm Imax(8/20мкс), А Vrms, V VDC, V Wmax, J twork, ns Detailed information
LS40 39×37.5×8.1…14.1 40000 130

750
170

970
310

1200
< 25 Далее
LS41 39×37.5×8.1…11.4 50000 250

460
320

615
490

960
< 25 Далее
LS42 39×37.5×9.2…11.4 65000 130

750
170

970
310

1200
< 25 Далее
LS50 65×57×8.1…12.3 75000 130

550
170

745
490

1825
< 25 Далее

Additional information

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NORTH-WESTERN LABORATORY: NEWS
 
05.06 09 
Epcos has developed a new N95 power ferrite material with an exceptionally low power loss.



12.05 09 
New Epcos ferrite ring core sizes : N87 R20*12*6 and N87 R28*16*9



02.02 09 
New Epcos ferrite E core size : N87 E16/8/7,8 B66502GX187



 
 


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