All 60950-1 Experts, I have in my device RS232 input line. I need to protect it against surge (because of EN 50130-4). Is it true that if I use the 33V varistor I will need to add a fuse in series with it (Cl. 1.5.9.2), but if I use the 33V TVS I need not to add the fuse. Cl. 1.5.9.1 note 1 tells me that TVS is not VDR (in 60950-1), so 1.5.9.2 not apply to it. Reading Cl. 2.4 I understand that 12V/10mA (RS232 driver capability) is not the LIMITED CURRENT CIRCUIT so VDR needs fuse. If the fuse is needed do the PTC resistor (for example Raychem miniSMDC020 - 0.2A/30VDC) can be considered as "an interrupting means having an adequate breaking capacity" ? If not the fuse with what approval should I look for ? In my opinion the same what can happen to the varistor during "-temporary overvoltages above the maximum continuous voltage." can happen to TVS. It is the reason I use 33V devices and not 12V ones. Thanks in advance for your answers. Best Regards Piotr Galka
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