UL single fault conditions

Status
Not open for further replies.
B

Bestboy4

Newbie level 1
Joined
Oct 30, 2017
Messages
1
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
14
So I have a board going through UL. UL claims that since it is over 15W that it needs to go through "special" testing. It is based on the 60730-1 standard (annex H.27). Apparently this gives them the license to short or open random components on the board (one at a time) to induce a fault. I have been an engineer for over 10 years and have never heard of such a test for industrial controls.

In my particular case, they removed a resistor in my 5V switcher circuit that sets the output voltage. When this occurs the output goes negative and causes a nice flame out of the my CAN transceiver. :bang:

Has anyone here have any experience with this UL requirement?
 

The thread below refers to similar UL tests. While designing a furnace igniter, the member was told he needed to solve various failure modes which occurred when shorting or opening any component. (It is discussed in the last 2 or 3 pages of the thread.) A testing department claimed such tests were typical at UL, and the design would not pass UL standards.

https://www.edaboard.com/showthread.php?t=256691
 

Single fault tolerance means in the present case that you need a means to protect the connected circuit against power supply failure, e.g. a TVS diode and a fuse.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…