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 A / TIP B / RING Protected Device Arrester Ground One 3-electrode arrester A / TIP Arrester B / RING Ground Protected Device 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 Arrester Protected Device 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 Shielding Line Corductor Arrester Ground 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 a a’ Ground b b’ B. 3-electrode arrester over-voltage protection circuit a a’ Ground b b’ C. Over-voltage and over-current protection circuit of 3 - electrode arrester with failsafe mechanism. a a' a a' ˙ Ground ˙ b b' D. Over-voltage and over-current protection circuit of 2 - electrode arrester with PTC thermistor. a a' b Ground b b' E. Over-voltage and over-current protection circuit of 3 - electrode arrester with PTC thermistor. a a' Ground b b' F. Over-voltage and over-current protection circuit of 3 - electrode arrester with PTC thermistor and failsafe mechanism. a a' Ground b b' Ground b' 2-Electrode Ceramic Surge Arrester Electrical Characteristics Impulse Impulse Impulse AC type Spark-over Spark-over discharge current discharge current discharge current ( JN ) voltage(100V/S) voltage(1KV/us) (10/1000us 300times) (8/20us10times) (50Hz 1s 5times) V V A KA A V DC Holdover Insulation Voltage resistance Ω Capacitance pF 2R-75A2 2R-75A2L 2R-75A3 75±25% ≤600 50 5 5 / ≥1010 <1.5 90±20% ≤600 50 5 5 / ≥1010 <1.5 150±20% ≤700 100 5 5 80 ≥1010 <1 100 5 5 135 ≥1010 <1 2R-75A4 2R-90A2 2R-90A2L 2R-90A3 2R-90A4 2R-150A2 2R-150A2L 2R-150A3 2R-150A4 2R-230A2 2R-230A2L 2R-230A3 230±20% ≤800 2R-230A4 2R-350A2 2R-350A2L 2R-350A3 350±20% ≤800 100 5 5 135 ≥1010 <1 470±20% ≤900 100 5 5 135 ≥1010 <1 600±20% ≤1200 100 5 5 135 ≥1010 <1 2R-350A4 2R-470A2 2R-470A2L 2R-470A3 2R-470A4 2R-600A2 2R-600A2L 2R-600A3 2R-600A