Metal ceramic gas discharge tube
GDT metal ceramic gas discharge tube is mainly composed of two metal electrodes, there is a certain gap between the electrodes, a stable inert gas is filled between the electrodes, and a certain pressure is maintained, which is formed by using ceramics and sealing. Protection device, called ceramic gas discharge tube
• It has fast response speed, response time ≤100nS,
• It is a switch-type lightning protection device connected in parallel to the circuit and bypassing the inrush current
• The voltage specifications range from 70V to 6000V, and the surge current withstand capability ranges from hundreds of amps to tens or even hundreds of thousands of amps
• Diverse package dimensions, Φ5.5 * 6, Φ5.0 * 7.2, Φ8 * 6, Φ8 * 8, Φ8 * 10, Φ11, Φ20, Φ25, Φ32, 6.2 * 4.2, 4.0 * 4.2, 1812 (4532 ), 1206 and other ceramic gas discharge tubes of different specifications
• Low capacitance value, generally only a few picofarads
• No polarity, easy and simple installation
• High insulation resistance, not easy to aging, strong reliability
• Dedicated to high-frequency communication signal lines for protection, generally cannot be used directly on active circuits for protection
Since the metal ceramic gas discharge tube has a problem of freewheeling and cannot be directly used for protection on active circuits, the protection on active products must use voltage-limiting protection devices (varistor or lightning-proof HYPERFIX Etc.) Used in conjunction.
Metal ceramic gas discharge tubes are widely used in consumer communication products to protect semiconductors and sensitive devices to prevent ICs from being damaged by transient overvoltages and being damaged
• Overvoltage and anti-lightning protection for communication equipment: such as ADSL, MODEM, CATV, IC card telephone, Ethernet switch, network card, voice splitter, telephone, fax machine, RS485, RS232 port, antenna, mobile base station, patch panel , Duplexer, etc.
• Due to the high pulse breakdown voltage of the discharge tube, it is generally safer and more reliable to perform two-pole protection when selecting and designing.
Junyao metal-ceramic gas discharge tube products meet the relevant provisions of RoHS WEEE and pass the inspection of corresponding testing institutions to meet their corresponding test standards: IEC61000-4-5, GB9043, ITU K21, IEC61643-311, GR1089, UL and other standards
Selection principle of metal ceramic gas discharge tube
DC spark-over voltage: defined as the breakdown voltage measured with a rising voltage of 100V / S or 1000V / S is called the DC breakdown voltage, which generally meets the range of ± 20% of the nominal DC breakdown voltage;
Impulse spark-over voltage: defined as the breakdown voltage measured with a rising voltage of 100V / uS or 1000V / uS called the pulse breakdown voltage
Nominal impulse discharge current: defined as the nominal pulse discharge current refers to the 8 / 20μs lightning current that the discharge tube can withstand.
AC discharge current: refers to the ability of the discharge tube to withstand 50HZ mains frequency AC current
InsulaTIon resistance: a certain voltage is applied to the two ends of the discharge tube, and the insulation resistance value is tested
Capacitance: refers to the parasitic capacitance value at both ends of the discharge tube
Selection of voltage of metal ceramic gas discharge tube
• DC spark-over voltage: The DC breakdown voltage must be greater than the maximum working voltage of the protected circuit. Due to the high pulse breakdown voltage of the ceramic gas discharge tube, it is generally considered in the selection and design of the secondary lightning protection concept Avoid damage to the protected circuit IC due to high residual voltage.
Selection of flow rate of metal ceramic gas discharge tube
• It is generally selected according to the requirements of the lightning protection test level of the customer ’s product to determine the flow rate and corresponding size specifications of the selected discharge tube
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