[quote]Hi,
I am basically an EMC guy and do not know much about UL requirements. I
would like to know if there are any UL requirements for a driver with
output voltage swing of +/- 30V peak-to-peak. The RMS voltage will be much
smaller, and the power will be less than 0.5 watt. The driver is to be
used to activate an off-card electromagnetic coil, and a flex cable will be
used as interconnect.
I will appreciate your replies.
Regards, Ravinder
PCB Development and Design Department
IBM Corporation
Email: ajm...@us.ibm.com
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Always do right. This will gratify some people and astonish the rest.
..... Mark Twain
[/quote]
Hi Ravinder:
I am assuming that the 30 V peak-to-peak will be accessible to the user. There
are two UL issues regarding your 30 V peak-to-peak voltage:
1. Isolation of the voltage from hazardous voltages, e.g. mains voltage. The
isolation must be comprised of two safeguards:
-basic insulation plus a grounded barrier;
-basic insulation plus supplementary insulation;
-reinforced insulation (a single insulation equivalent to double insulation.
Each insulation must be a UL-Recognized insulation or plastic. The
grounded barrier must be constructed in accordance with the multitude of
requirements specified in the applicable standard.
2. The voltage must not exceed:
-30 volts rms;
-42.4 volts peak;
-60 volts dc.
Assuming the waveform is symmetrical, 30 volts peak-to-peak is less than 42
volts peak. So, your voltage meets the requirements.
If the 30 volts peak-to-peak is not isolated from the mains as described above,
then the insulation of the 30 volts peak-to-peak must not be accessible and the
insulation interposed between the operator and the 30 volts p-p must be at
least basic insulation, and *may* need to be the same insulation as mains
insulation (listed above).
The answer to your question is well beyond what we can do via e-mail. I've
only touched on the basic construction; there are many more applicable
requirements.
Best regards,
Rich
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