T-Artificial Mains Network

See page 9 here (warning: large pdf download):
http://www.telegesis.com/downloads/general/EMC test report.p...

The doc. is from a major EMC test lab in Germany.

Back-translating, I guess RBLT means 'réseau à large bande-T'. I'm not sure what the 'T' stands for, but it doesn't matter for Asker's question :)

--------------------------------------------------
Note added at 1 hr (2011-08-05 22:34:10 GMT)
--------------------------------------------------

Having found references to this same piece of equipment in Spanish, where 'T' is replaced by 'V' (very often implying a bifurcation) I reckon the 'T' refers to a splitter.

Here's an R&S document that clearly refers to the ESH3-Z4 as simply a T-network, and goes on to explain what it is used for:

http://www2.rohde-schwarz.com/file_4218/Escs_bhl.pdf

--------------------------------------------------
Note added at 1 heure (2011-08-05 22:10:13 GMT)
--------------------------------------------------

Thinking about it, networks for coupling into 2 lines might well be of T or V form (and cf. remembering T and ∏ pads, for example)

--------------------------------------------------
Note added at 9 heures (2011-08-06 06:17:05 GMT)
--------------------------------------------------

Here is an advert for a second-hand device, of the actual model number in Asker's context, which refers to it as a "Rohde & Schwarz / R&S ESH3-Z4 T-Network EZM 800.1510.52" (and priced at a much more reasonable $450)

http://www.used-line.com/c6192491s136-Rohde_Schwarz_R_S_ESH3...

Note that it is not clear what the 'EZM' refers to, but the following 9-digit number might be a serial number, as seen in Asker's list above)

Here is another ref. where it is referred to as a T-network, without the 'EZM' bit, which seems as if it might be something of a red herring, since only one ref. actually cites it.

HF TEST RECEIVERS field - strength

www.helmut-singer.de/pdf/rsesh3.pdf

... T .network. ESH 3-Z4.
- Two-line V-network. ESH 3-ZS ...
model 56 with Spectrum Monitor EZM (model 56) ...

--------------------------------------------------
Note added at 9 heures (2011-08-06 06:31:47 GMT)
--------------------------------------------------

p 2-6 of the R&S document I referred to above seems to suggest that the ESH3-Z4 is used for the actual measurement, apparently setting it apart from the LISNs (though the text is not entirely explicit on this point) I quote:

"If none of the LISNs is switched on, the RFI voltage measurement is made on one line only. This is the case if a probe, a single-phase V-network (ESH3-Z4, ESH3-Z6) or an RF probe is to be used for
the measurement."

It is unfortunate that here they seem to incorrectly refer to it as a V-network rather than a T-network!

--------------------------------------------------
Note added at 9 heures (2011-08-06 06:34:39 GMT)
--------------------------------------------------

OK, in Asker's list above, the ESH3-Z6 mentioned is referred to as a V-network (one of the RSILs — it seems as if it may be a single-phase one)

So it seems again as if some kind of distinction is being made between the RLBT and the RSIL, without it's yet having been explained.

--------------------------------------------------
Note added at 9 heures (2011-08-06 06:38:17 GMT)
--------------------------------------------------

Right, on p 4-27 of the same document, we finally get to:

"If both LISNs are OFF, the RFI voltage measurement is made on one line only. This is to be determined if a probe, a single-phase LISN (ESH3-Z4), ESH3-Z6) or an RF probe is to be used for the measurement."

So it does indeed seem as if this ESH3-Z4 is a specific kind of LISN, though why the FR acronym is RLBT is still a mystery.

I still favour using what appears to be the device manufacturer's own term, without trying to interpret what the actual acronym stands for.

--------------------------------------------------
Note added at 1 jour16 heures (2011-08-07 14:05:16 GMT)
--------------------------------------------------

This looks like a useful document to refer to:

http://www.elmac.co.uk/pdfs/ff26_report.pdf

--------------------------------------------------
Note added at 1 jour17 heures (2011-08-07 14:09:48 GMT)
--------------------------------------------------

OK, from the above document, we have some useful information:

"For the specific purpose of making conducted emissions voltage measurements on the mains input of apparatus,
CISPR 16-1 [3] defines a transducer known as an Artificial Mains Network (AMN). The US term Line
Impedance Stabilisation Network (LISN) is in more general use and usually means the same thing, although
strictly speaking it can be applied to a stabilising network intended for any type of line. The AMN/LISN has
three main purposes:
· to define the RF impedance seen by the EUT’s mains port. Otherwise, tests done on the same EUT
with different mains supplies would not be repeatable.
· to couple the interference signal from the EUT mains terminals to the measuring instrument in a
defined fashion, and to prevent the mains voltage from being directly applied to the measuring
instrument.
· to reduce extraneous ambient noise that might be present on the incoming mains circuit.
Several variants of AMN/LISN are specified in CISPR 16-1, but one in particular (the “50W/50mH + 5W”
version) has become established as the norm and is widely available from commercial suppliers. Other
impedance stabilising networks are specified for military, aerospace or automotive tests or are defined in draft
specifications for signal or control ports. These are not discussed in this document.
For the investigations which form the basis of this section, five manufacturers’ AMN/LISNs were used and
compared:
· MN2050C, Chase EMC, UK
· L2-16, PMM, Italy
· LISN 1600, Thurlby Thandar Instruments, UK, supplied by Laplace Instruments
· ESH3-Z5, Rohde & Schwarz, Germany
· 4825/2, EMCO, USA"

--------------------------------------------------
Note added at 1 jour17 heures (2011-08-07 14:15:06 GMT)
--------------------------------------------------

So we now have the explanation for the difference in distribution of the two terms, and the technical nicety of usage between them; it seems that RSIL = either LISN or AMN, but we still have no hard-and-fast proof that the Z4 is exactly the same thing (though it seems in all likelihood it must be!).

I'm still tending towards my hunch that this is to do with powering the telephone at DC instead of at mains voltage, which seems to be borne out by the other list items' including a 48 V LISN.

--------------------------------------------------
Note added at 1 jour17 heures (2011-08-07 14:24:26 GMT)
--------------------------------------------------

OK, I've just taken a closer look at the Helmut Singer document I cited above; sadly, it's an image PDF, so I can't copy-&-paste the text here, but in the equipment list on page 2, it lists and to some extent explains as follows:

The following accessories are available for measuring interference voltages, currents and field strengths according to the relevant standards (CISPR, VDE, MIL, VG):

...
- T-network ESH3-Z4
- 2-line V-network ESH3-Z5
- V_network 5µH / 50 Ω ESH3-Z6
...


It would seem that what makes the RLBT different from the RSIL is the fact that it is a T rather than any kind of V network. The mains or not issue remains unresolved.

--------------------------------------------------
Note added at 2 jours14 heures (2011-08-08 11:19:45 GMT)
--------------------------------------------------

Right, I have a direct answer from R&S UK, though it seems curiously at odds with what we've found out so far.

Apparently, the ESH3 is an old 30MHz Test Receiver. The ESH3-Z4 is a Spectrum Analyser that is connected via their special T-network

So it seems as if perhaps the -Z4 part is the accessory, and any mention of LISN's etc. is perhaps referring to the way in which the main item of equipment is being connected up (rather than directly to this specific device).

To some extent, this does make sense, inasmuch as while the primary test equipment must of course be traceable and identified by serial number etc., one might perhaps hardly expect the smaller accessories to be listed in the same way.

I am still puzzled by the way this is all listed, but perhaps overall, Claude can make head or tail of it all!

--------------------------------------------------
Note added at 5 jours (2011-08-11 12:25:30 GMT)
--------------------------------------------------

OK, so it's a low-voltage LISN with a T-network connection — so glad we got there in the end!

--------------------------------------------------
Note added at 5 jours (2011-08-11 15:59:49 GMT)
--------------------------------------------------

I take M/M's point about BT meaning mains voltage in some contexts — usually, specifically to do with power distribution, generation, etc.

However, in this particular context of EMC testing, I'm still inclined to think they're referring to 'low voltage' in the more 'ordinary' sense, in the same way that some of the later RSILs are referred to as being '48 V'.