Types of surge arrester-cataloge
1937 CITEL founded. Manufacture of
tubular light bulbs.
1944 Manufacture of the first Surge Arrester.
1976 CITEL acquired by the present
Management. Light bulb manufacture discontinued.
1985 CITEL America founded in Miami.
1988 CITEL GmbH founded in
Düsseldorf.
1992 Acquisition of the CLAUDE gas tube line from GTE
Sylvania.
1996 Acquisition of SUPER
SAFE in the Netherlands.
1996 Founding of Shanghaï CITEL Electronics Co., Ltd.
1998 CITEL listed on the Paris Stock Exchange.
1999 New Headquarters.
2001 Founding of Protecoes Citel Ltda (Brazil)
The specialist in overvoltage protection
CITEL's only business is protecting networks and equipment from
transient
overvoltages, in particular those induced by lightning. For this, CITEL
manufactures two complementary basic products:
- Gas discharge tubes (or GDTs) are the basic passive components used to
protect telephone exchanges and equipment from voltage surges; they are
generally installed on telephone networks by telecommunications
operators.
- Surge Protection Devices (or SPDs) are subassemblies combining several
protection components. They may be used by the installer or by the end customer.
They are designed to be incorporated in an installation
to protect all electric, electronic, and data-processing equipment from
transient overvoltages.
The origin of overvoltages
Transient overvoltages have four main causes :
Lightning
Industrial and switching surges
Electrostatic discharges (ESD)
Nuclear electromagnetic pulses (NEMP)
The overvoltages of different origins differ in amplitude,
energy, waveform, and recurrence rate.
Lightning and industrial overvoltages have been with us for a long time, but ESD and NEMP disturbances are much more specific and arise from recent
technological developments (massive use of semiconductors for the former,
thermonuclear weapons for the latter).
There are three types of indirect electrical effects :
Impact on overhead lines
Rise in ground potential
Electromagnetic radiation
Overvoltages have any many types of effects on electronic equipment; in order of decreasing importance:
Destruction
Voltage breakdown of semiconductor junctions
Destruction of bonding of components
Destruction of tracks of PCBs or contacts
Destruction of triacs/thyristors by dV/dt.
Interference with operation
Random operation of latches, thyristors, and triacs
Erasure of memory
Program errors or crashes
Data and transmission errors
Premature ageing
Components exposed to overvoltages have a shorter life.
Surge Protection devices
The Surge Protection Devices (or SPD : this is a generic name for any
device to protect from voltage surges) is a recognized and effective solution to
the overvoltage problem. For greatest effectiveness, however, it must be chosen
according to the risk and installed in accordance with the rules of the art.
Because of the diversity and importance of transients, standards organizations have created specifications for testing the reactions of equipment to overvoltages. The phenomena were first characterized and a series of standardized waves created (1.2/50s voltage wave and 8/20s and 10/350s current waves), then a number of standards defining surge arrester performance were issued, among them :
Surge Protectors for low-voltage installations :
NF EN 61643-11 (France)
EN 61643-11 (Europe)
UL 1449 (USA)
IEC 61643-1 (International)
Surge Protectors for Telecom equipment :
IEC 61643-21 (International)
ITU-T recommendations K11, K12, K17, K20, K21, K36 (International)
UL 497 A/B (USA)
For more information, please contact us.
Copyright©2005 Thunder Electronic Eng. Co. All rights reserved.