Gas Tube Su rge Arresters and Switching Spark Gaps : Application The main application of Gas-filled surge arresters is in over - voltage protection of telecommunication installation ranging from MDF in exchanges to end equipment at subscribers. With the increase in use of computers, facsimiles and modems, the ceramic arrester can not only offer optimum protection in over-voltage for them but also for the cable television with its extensive cabling and sophisticated amplifiers. 1. The Example Of Application : A. Telephone / FAX / Modem protection 230V / 350V Arrester Two 2-electrode arresters One 3-electrode arrester Telephone/fax/modem protection Telephones ,faxes and modems are increasingly being equipped with sophisticated electronics .Typical circuits used to protect them with surge arresters are shown in Fig.1.In the event of an overvoltage ,the arrester protects both exchange lines by conducting the surge current away to ground. B. Signal Line Protection Typical: 75V/ 90V/ 230V Arrester A2-electrode arrester Signal line protection Signal circuits are often run with no ground conductor .A 2-electrode arrester circuit located between the two signal lines prevents the formation of large potential differences at the input of the equipment to be protected before they can cause any damage C. AC Line Protection Typical: 270V Arrester/for 110Vac 470V Arrester/for 220Vac 600V Arrester/for 220Vac 800V Arrester/for 400Vac Line Varistor Neutral Arrester ● Ground AC line protection Telecommunications installations as well as CATV amplifiers ,CB transmitters ,home entertainment systems ,computers and similar equipment can be exposed to voltage surges conducted via the power network .The combination of a surge arrester and a varistor offers proven protection in these cases .The phase and neutral conductors are connected to ground potential of both protection elements. D.CATV/Coax Line Protection Typical 150V/230V Arrester Cable TV/coaxial cable protection Arresters are particularly well suited for protecting the coaxial cables frequently laid in CATV networks ,as they do not disturb the system even at high frequencies thanks to their low self-capacitance of typ.0.5 to 1 pF .The arrester is contained in the coaxial protection module where it is connected between the central conductor and the shielding .lt is recommended to ground either the shielding or the housing of the protection module ,depending on the application 2. Basic Circuit of application A. 2-electrode arrester over-voltage protection circuit B. 3-electrode arrester over-voltage protection circuit C. Over-voltage and over-current protection circuit of 3 - electrode arrester with failsafe mechanism. D. Over-voltage and over-current protection circuit of 2 - electrode arrester with PTC thermistor. E. Over-voltage and over-current protection circuit of 3 - electrode arrester with PTC thermistor. F. Over-voltage and over-current protection circuit of 3 - electrode arrester with PTC thermistor and failsafe mechanism. 2-Electrode Ceramic Surge Arrester Electrical Characteristics Impulse Impulse Impulse AC Spark-over Spark-over discharge current discharge current discharge current voltage(100V/S) voltage(1KV/us) (10/1000us 300times) (8/20us10times) (50Hz 1s 5times) V V A KA ≤600 100 90±25% ≤600 150±20% DC type Capacitance Holdover Insulation Voltage resistance A V Ω pF 10 10 / ≥1010 <1.5 100 10 10 / ≥1010 <1.5 ≤700 100 10 10 80 ≥1010 <1 230±20% ≤800 100 10 10 135 ≥1010 <1 350±20% ≤800 100 10 10 135 ≥1010 <1 400±20% ≤900 100 10 10 135 ≥1010 <1 420±20% ≤900 100 10 10 135 ≥1010 <1 470±20% ≤900 100 10 10 135 ≥1010 <1 600±20% ≤1200 100 10 10 135 ≥1010 <1 2R-75A5 2R-75A5L 75±25% 2R-75A6 2R-75A6L 2R-90A5 2R-90A5L 2R-90A6 2R-90A6L 2R-150A5 2R-150A5L 2R-150A6 2R-150A6L 2R-230A5 2R-230A5L 2R-230A6 2R-230A6L 2R-350A5 2R-350A5L 2R-350A6 2R-350A6L 2R-40A5 2R-40A5L 2R-40A6 2R-40A6L 2R-420A5 2R-420A5L 2R-420A6 2R-420A6L 2R-470A5 2R-470A5L 2R-470A6 2R-470A6L 2R-600A5 2R-600A5L 2R-600A6 2R-600A6L