Note that the Low Voltage Directive merely requires member states to
approve the import of only electrical products that are "safe". It
is not directed to manufacturers, nor does it say HOW a manufacturer
must meet this condition. Typically, one can either get a complete
CB Report to IEC 60950, or explain each and every aspect of the
equipment and how it prevents against the kinds of hazards listed.
These are the two extremes.
Now, what does the specified voltage range mean? The scope of IEC
60950 includes equipment that is mains or battery powered. Mains
voltages are hazardous, and batteries can generate terrific heat
when shorted, leading to fire.
The issue is where your 24V device gets its power. If the mains to
24V convertor is part of the equipment, it definitely falls into the
LVD range. If the 24V comes from "somewhere else", what is the
current (power) limitation coming into your device in the event of a
fault? What other limitations must be placed on the incoming power
bus to avoid the usual IEC 60950 hazards?
If you can demonstrate that the entire unit is 24V or below, and is
well protected against hazards induced from outside, it is possible
that it might fall outside the scope of the LVD.
George Alspaugh
Please respond to "Gary Labadie"
<glabadie%acromag....@interlock.lexmark.com>
To: emc-pstc%ieee....@interlock.lexmark.com
cc: (bcc: George Alspaugh)
bcc: George Alspaugh
Subject: Isolation versus IEC1010
I would like to get the consensus on the following concept.
The low Voltage directive applies to products that use 50VAC or 75VDC and
higher signal levels basically up to 1000VAC. Now, If a product's I/O
and power signals do not exceed 24Vdc anywhere, does the low voltage
directive apply. Here's the catch, the unit contains electrical
isolation between input, output and power signals. The electrical
isolation rating is specified as 250VAC continous.
Some argue, that since the unit is isolated and has an isolation rating
the Low voltage directive applies because the isolation specification
exceeds 50VAC. You can also argue that within the scope of the Low
Voltage directive that the I/O and power signals are below the directives
requirement and hence do not apply if you don't consider whether the
product has electrical isolation or not.
Does the fact that electrical isolation is included into a product,
affect whether the Low Voltage Directive may or may not apply?
Best Regards,
Gary Labadie
Marketing
Acromag, Inc.
30765 Wixom Rd. Ph: (248)624-1541 ext. 205
P.O. Box 437 Fax:(248)624-9234
Wixom, MI 48393 Email: glaba...@acromag.com
