Rich/Doug - Regardless of the input the output of the DC/AC inverter must comply with 2.4 of UL 1950 if it could be touched by the user. If it doesn't meet the requirement then it must be enclosed in a fire enclosure and provided a barrier to prevent service personal from accidentally touching it.
Mike Campi Corporate Compliance Engineer Fujitsu PC Corporation -----Original Message----- From: Rich Nute [mailto:[email protected]] Sent: Wednesday, March 24, 1999 12:10 PM To: [email protected] Cc: [email protected] Subject: dc-to-ac inverter. Hi Doug: > My question is this, is it because the inverter has a low voltage input and > they do not have to comply to a standard like EN61010 or UL1950, or is this > something the manufacturers haven't addressed because no one has ever asked? I don't think anyone but the manufacturers can answer your question. It is certainly easy to say that because the unit is rated for less than 50 V input, it is exempt from the LVD. The inverter is essentially a UPS with an external battery and without the monitoring and switchover features. So, the applicable safety standards would be those for UPS. In the USA, under the NEC, the inverter would be considered a separately-derived source. The NEC requires such sources to be grounded. At 300 watts output and 12 volts, the input current would be more than P 300 I = ----- = ------- = 25 amperes E 12 Assuming at least 60 watts consumed in the inverter operation, input current would be 30 amperes! So, one major safety issue is that of overheating (and fire) due to normal and fault-mode currents. Another major safety issue is the isolation of the 120 volts from the 12 volts. Yet another is that of grounding, both the neutral and protective conductors, of the 120-volt source. So, there are real safety issues with such an inverter. Best regards, Rich ------------------------------------------------------------- Richard Nute Product Safety Engineer Hewlett-Packard Company Product Regulations Group AiO Division Tel : +1 619 655 3329 Effective 6/12/99: +1 858 655 3329 16399 West Bernardo Drive FAX : +1 619 655 4979 Effective 6/12/99: +1 858 655 4979 San Diego, California 92127 e-mail: [email protected] ------------------------------------------------------------- --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators). --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
