RE: EN60950-1 Sect 2.5 Limited Power sources PTC's

For the record - I was doing a Single Fault analysis on a product that used a PTC and a relay to prevent welding switch contacts. (No it was not my idea - because...) when I got the engineer to simulate a s/c PSU the PTC exploded - sent burning material out through (compliant) ventilation slots

Re: EN60950-1 Sect 2.5 Limited Power sources

Hi Tom: Is it permitted to use PTC as an overcurrent protective device for power sources not inherently limited? I don't have EN60950-1 here, but I remember it must be a fuse or other non-autoreset device. I said: The trick is to determine if your test houses can

Re: EN60950-1 Sect 2.5 Limited Power sources

On Tue, 3 Sep 2002 15:49:43 -0700 (PDT), Rich Nute ri...@sdd.hp.com wrote: If you use a PTC, then your output need not necessarily be considered inherently limited. In this case, your maximum output current is 100 amps and your maximum VA is 250, i.e., 25 amps (with the PTC shorted).

Re: EN60950-1 Sect 2.5 Limited Power sources

Hi Alex: We use a linear (basically a transformer with a PTC thermistor) class II SELV O/P stand alone power supply rated 10Vac, 5A. One of the labs tested the O/P Isc with a direct application of the sc. The other lab tested the O/P Isc by applying a load of 8A. The results were

RE: EN60950-1 Sect 2.5 Limited Power sources

own testing. See clause 1.5.2. Bob Johnson ITE Safety -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of Alex McNeil Sent: Friday, August 30, 2002 5:25 AM To: 'emc-p...@majordomo.ieee.org' Subject: EN60950-1 Sect 2.5 Limited

RE: EN60950-1 Sect 2.5 Limited Power sources

...@ingenicofortronic.com] Sent: Friday, August 30, 2002 11:25 AM To: 'emc-p...@majordomo.ieee.org' Subject: EN60950-1 Sect 2.5 Limited Power sources Hi group, I have a query on the understanding of the above section. I thought I fully understood it until I used a different lab for Product Safety Compliance testing

EN60950-1 Sect 2.5 Limited Power sources

Hi group, I have a query on the understanding of the above section. I thought I fully understood it until I used a different lab for Product Safety Compliance testing (both accredited!). We use a linear (basically a transformer with a PTC thermistor) class II SELV O/P stand alone power supply