It _is_ true that the equipment must be functional after the lightning tests.
Lightning is just one of the tests that are to be performed. The others are power induction and power contact (aka power cross). One must consider these other tests in designing in a protection scheme for these requirments. Typically, Gas Discharge Tubes are not used on subscriber equipment for the lightning requirement. They are typically used as primary protectors. Zeners, as well as MOV's are also suitable to meet this. To meet the other test requirements, fuses, fusing resistors and PTC's would allow you to comply. The power induction test requies functionality afterwards, while power cross does not, but it must not cause a fire. PTC's have the advantage in many situations as they are resetable devices, vs. one shot devices. This would help in your equipment being functional after the test. mj > Hi everyone, > A question on K.21 testing: I am looking for some > information/advice on the requirement for CE mark and EN60950. How is > this test done and what are the requirements? It is my understanding > that originally the product (modems connected to PSTN) were only > required to shut down when zapped by the high voltage test, in this > case a fuse could be used along with a gas discharge tube. Now the > requirement is that after the surge, the modem must still function as > before. Is this true? any advise on possibly using a combination of > GDT, polyfuse, thyristor? Thanks in advance! > > sd > > correction... The subject above should be lightning surges and how to >best > pass this test. ------------------------- Michael Jamison Raychem-PolySwitch Voice: 415-361-2608 Fax: 415-361 4585 email: [email protected] or [email protected]
