Sender: [email protected] From: Bob Lee <[email protected]> Organization: N.E.T. http://www.net.com Subject: Re: I-CTR 37
Hello Edward, By chance any relaxation on the TBR 21- 60 mA current limit looking into 50V battery w/230 Ohms? I have sent prior concerns on this, as, on short (co-located) loops we are talking about 2.2 Watts dissipation per port. We have 4 ports which, will then dissipate 8.8 Watts in a very small air restricted volume. I understand that France brought this requirement into the TBR 21. Surely, this must also thermally burden even their own manufacturer's of terminal equipment. Currently, we cannot ship until our (FXO/PSTN) interface is completely redesigned for adequate heatsinking. Apparently, this restriction has lessened the office heat issues but has shifted it to the terminal equipment. However, the offices are better equipped to handle this given their investments in air conditioning (if I could add a small air conditioner to a plug-in module w/o significant costs, etc., then I would :). I believe this restriction is outdated, unfair and it s/b relaxed (typical North American heat dissipation under similar short loop conditions is only about 1/6 as much and is workable). Like to hear more on this.... cheers, bob lee Edward Fitzgerald wrote: > > Sincere apologies for my previous misleading email, the draft I-CTR > places relaxation on TBR 21 to the following extent:- > Annex IV > 1. Range of feeding conditions. > > The following relaxation applies to requirements of the standard > referred to in Annex I (TBR21) in clauses 4.6.2, 4.7 (including all > applicable subclauses) and 4.8 (including all applicable subclauses). > > The resistor of 3 200 Ohm shall be replaced by a resistor of 2 800 Ohm. > > 2. Range of feeding conditions for terminal equipment not intended to be > connected to any PSTN supplying a loop current of less than 18 mA. > > The following relaxation applies to requirements of the standard > referred to in Annex I in clauses 4.6.2, 4.7 (including all applicable > subclauses) and 4.8 (including all applicable subclauses). > > For terminal equipment declared by the manufacturer for use only on > lines providing a loop current of 18 mA or greater, the resistor of 2 > 800 Ohm shall be replaced by a resistor of 2 300 Ohm. > > Best regards, Edward > > Edward Fitzgerald > International Approvals Consultant > Direct Tel. : +44 1202 20 09 22 > GSM Tel. : +44 4685 33 100 > > European Technology Services > Specialist Global Compliance Consultancy > Offices in Australia, Canada and the UK. > http://www.ets-tele.com/tics
