This sounds a lot like the keyed RF test we do on protective relays (power
line protection). For our case, the rise and fall times of the pulse are
specified to be less the 50 microseconds. (The modulation pulse
specification is very open - minimum of 0.5 sec on and off time) Assuming
50 microsecond rise/fall time, the phase of the RF carrier makes little
difference, as it takes several cycles of RF to make the transition even at
the lowest RF frequency. Does your standard specify rise/fall time of the
pulse modulation?
Donald Borowski
Schweitzer Engineering Labs
Pullman, WA, USA
Kevin Harris
<kevinharris2@dsc
.com> To
Sent by: [email protected]
[email protected] cc
Subject
02/09/2006 08:59 Conducted Immunity Question
AM
Hello Group,
I recently been discussing conducted immunity testing with some colleagues
and we have discovered that we have differing opinions on the intent of the
standard. In particular we are referring to the EN 61000-4-6 in pulse mode
testing. Our product family standard EN50130-4 calls out this base standard
with a 1HZ 50% duty cycle pulse rate.
The discussion centers around synchronization of the modulation source (1
Hz) and the RF. The standard does not specify explicitly that these signals
should be synchronized but one of us feels that it must be so by
implication.
If one assumes no synchronization ( i.e.. The modulation signal is free
running and at some point the RF is enabled ) then the first and last
pulses of the train can be of any length (up to 1/2 period) and not the 1Hz
50% pulse called for. The concern here is this would add some unknown
uncertainty to the test as well as reproducibility issues. The counter
argument to that is, the on off time is really irrelevant, and that any
issue arising from uncertain pulse length, should be classed as a failure,
as that perhaps is more "real world".
What do you feel? Is synchronization important here? Is a non synchronized
test system compliant with the standard?
Thanks
Kind Regards,
Kevin Harris
Manager, Approvals Group
Digital Security Controls
3301 Langstaff Road
Concord, Ontario
CANADA
L4K 4L2
Tel: +1 905 760 3000 Ext. 2378
Fax +1 905 760 3020
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