The TR1,2 are steps with a rise-time, however they are also
described as having a current limit. If the source current
limiting kicks in, then the end of the transient doesn't occur
until the limiting ceases. The easiest reference is the beginning
of the transient because there are no ambiguities.
I think this was the intent early-on, however as you point out,
the rules aren't clear, and neither are the origins (at least in a
quick search). The existing text doesn't explicitly reference the
During a transient the
input power of the PD may exceed PPeak_PD or
PPeak_PD-2P. Table 145–30 defines
three PSE output voltage transients.
When transient TR1 or TR2 is
applied, the PD shall meet the
operating power limits after TTransient as
defined in Table 145.
However If the intent was to reference the end of the transient,
I would think the second sentence would have been:
AFTER transient TR1 or TR2 is
applied, the PD shall meet the operating power
limits after TTransient as
defined in Table 145.
In any case, the TR1,2 test requirements are an extreme corner
case and there's no longer any suggestion to the reader that
specific capacitances will "intrinsically" pass, so I don't see a
problem with the reference being at the beginning.
On 11/1/2017 8:29 AM, Lennart Yseboodt
The PD not spending more than 6ms or 10ms in the
current-controlled mode is also something the PD should meet.
We currently do not have a requirement for this (ie. it is
possible to meet TR1/TR2 but spend more than TLIM in the input
Note that all Class/Type combinations currently do not
The current text does not offer a reference for Ttransient. I
picked the end of the source transient because it is an easy to
If we shift the reference point backward in time, the PD
margin decreases and we may have to increase ILIM to TLIM to
make things work again.
- Should we add a requirement to the TR1 and TR2 that the PD
may not be current limited to ILIM for more than TLIM ?
- Given that currently there is no issue with TLIM, do you
still feel we should move the reference point back ?
On Mon, 2017-10-30 at 09:39 -0400, Ken wrote:
The new text: "referenced from when the ‘final voltage’ is reached at
the source", sets a time boundary which is after the time that the PD
starts to violate Ppeak_PD. Seems like it should start at the beginning
of the transient, so that the PD Peak excursions that are beyond
Ppeak_PD are no wider than 10ms and 6ms, to match Tlim_min in the PSE
On 10/29/2017 10:09 AM, Lennart Yseboodt wrote:
Attached proposed baseline for the PD transients section.
At the September meeting it became obvious that Table 145-30 wasn't
I've re-simulated all of the transient conditions and, except for
Class 7, everything is OK.
We may want to consider increasing the ILIM for Class 3, Class 4, and
Class 8 to make it such that PD's that "intrinsically" should be fine
See simulation_annot.pdf for simulation results.