Pspice Model Surge Arresters Pb

EPCOS Product Brief 2012

PSpice Model for Surge Arresters Analog Behavioral Model for Circuit Simulation

Voltage surges in telecom or power systems caused by lightning or line faults can affect sensitive electronic circuitry. Manufacturers of telecom equipment such as subscriber terminal boxes, DSL modems and power equipment or switched power supplies and UPS batteries are legally obliged to take overvoltage protection measures. Gas discharge tubes (GDTs) are typically used to shunt surge currents to ground and limit overvoltages to a harmless level. Their key advantages are their high surge current handling capability combined with a very low capacitance and high insulation resistance. EPCOS is the only manufacturer of surge arresters to offer simulation assistance and support for gas filled dis-

charge tubes. Any arrester from the EPCOS product range can be entered into a PSpice model upon request. This allows users to fit the GDT into their designs at an early stage of development. Any effects occurring during normal operation as well as the behavior of the whole circuit under surge simulation can then be tested prior to building a A prototype. This offers significant advantages such as cost savings and a reduced development time E_UAS for new designs. IN+ OUT+ IN-

E_UAG Rmeas

OUT-

EVALUE

Applications

zz Analog circuit simulation Cgap zz System design and verification zz Functional verification EPCOS M50-C90XSMD zz Surge simulation Parameters: R iso

UAG = 90 Riso = 1 G Cgap = 1 p Iarc = 800 m Uarc = 15 Uglow = 60

IN+

OUT+

IN-

OUT-

EVALUE

RShunt

S_Volt + + S_ST

Rflux2 L3

S_Arc

E_Arc

+ + S_ST

OUT+

IN+

OUT-

IN-

S_Glow

E_Glow

+ + S_ST D1

EVALUE

OUT+

IN+

OUT-

IN-

EVALUE D2 B

www.epcos.com

PSpice Model for Surge Arresters

Simulation of gas discharge tubes

The model features the given values from the data sheet, including:

EPCOS provides network listings for specified arresters upon request. They are set up with ORCAD PSpice 16.3 and can be implemented in almost any Spice simulation program running basic libraries (such as ABM, ANALOG, BREAKOUT and SPECIAL). The very fast switching processes of arresters make the model highly CPU-intensive. When using fast transients (>0.1 kV/µs), the recommended step size for the simulation is 100 ns. Higher values may lead to deviating simulation results. The present design does not consider environmental factors such as heat dissipation and is purely ideal (excluding any variance). It is up to the user to determine the service life of the simulated arrester.

zz DC spark-over voltage zz Impulse spark-over voltage zz Gap capacitance zz Insulation resistance zz Arc voltage zz Glow voltage zz Arc transition current zz Extinguishing current

Circuit diagram of the simulation This diagram shows a basic version of the arrester subcircuit in the PSpice model. The design can be fitted into a library file and used just like any other component in the editor.

A E_UAG E_UAS IN+

OUT+

IN-

OUT-

Rmeas

EVALUE

IN+

OUT+

IN-

OUT-

EVALUE

RShunt

S_Volt + + S_ST

Rflux2 L3

Cgap

R iso

EPCOS M50-C90XSMD Parameters: UAG = 90 Riso = 1 G Cgap = 1 p Iarc = 800 m Uarc = 15 Uglow = 60

S_Arc

E_Arc

+ + S_ST

OUT+

IN+

OUT-

IN-

S_Glow

E_Glow

+ + S_ST D1

EVALUE

OUT+

IN+

OUT-

IN-

EVALUE D2 B

Surge simulation The diagram shows the simulation result of an EPCOS arrester with 90 V DC breakdown voltage. The arrester is placed line-to-ground with a simulated 80 V AC source. At the 4 ms mark, a surge (8/20 µs, 1 kV peak) is applied to the line (green graph at top). It can be seen that the arrester limits the overvoltage to ~180 V (the simulated impulse breakdown voltage). It then enters its arc mode (~20 V) and the surge current is shorted to ground (red graph at bottom). As soon as the follow current drops below a certain level, the arrester extinguishes and its internal resistance immediately returns to its initial very high value (9 ms mark).

Important information: Some parts of this publication contain statements about the suitability of our products for certain areas of application. These statements are based on our knowledge of typical requirements that are often placed on our products. We expressly point out that these statements cannot be regarded as binding statements about the suitability of our products for a particular customer application. It is incumbent on the customer to check and decide whether a product is suitable for use in a particular application. This publication is only a brief product survey which may be changed from time to time. Our products are described in detail in our data sheets. The Important notes (www.epcos.com/ImportantNotes) and the product-specific Cautions and warnings must be observed. All relevant information is available through our sales offices.

© EPCOS AG · A Member of TDK-EPC Corporation Edition 04/2012 · Ordering No. EPC:48009-7600 · Printed in Germany · PB 04122.