Newsgroups: sfnet.harrastus.elektroniikka
Subject: Re: Oman s�hk�laitteen myyntiinsaattaminen
References:  <[email protected]>   
Tomi Holger Engdahl  writes:

> Jouko Holopainen  writes:
> 
> > Tuomo Auer wrote:
> > > http://www.tkk.fi/Misc/Electronics/faq/sfnet.harrastus.elektroniikka/maarayksia.html ja sielt� CE-merkint� noin puolenv�lin kohdalla.
> > 
> > "S�hk�turvallisuusm��r�yksiss� on olemassa suojaj�nnite, joka on 42
> > volttia. Vaarallisia j�nnitteit� ovat t�t� suuremmat tasaj�nnitteet
> > ..."
> > 
> > ��� ... eik�s PoE (power over ethernet) ole 48 volttia? Eli PoE
> > laitteet olisivatkin yht� "vaarallisia" kuin 23oV laitteet, n�in
> > niinku asennusmieless�.
> > 
> > Hieman outoa.
> 
> 
> Tuohon 42V j�nniteraajaan on tiettyj� tapauksia, joissa sallitaan 
> suurempiakin j�nnitteit�. Esimerkiksi telepuolen piireiss� 60V 
> ei ole viel� mik��n hirve�n vaarallinen. Tietyill� ehdoilla 
> voidaan sallia tietyiss� tilanteissa isompia j�nnitteit� 
> aina jonnekin 100V DC luokkaan asti ilman ett� on 
> "hengenvaarallisia". Esimerkiksi noissa telepiireiss� 
> niist� saatavat tehot yms.. on rajoitettuja. 

Poimintoja: http://www.epanorama.net/links/safety.html#safety

Here are some general definitions considering electrical safety (from
IEC 60950 / EN 60950 glossary):

# Hazardous Voltage: A voltage exceeding 42.4V peak or 60V d.c.,
  existing in a circuit which does not meet the requirements for
  either a Limited Current Circuit or a TNV Circuit. 

# Limited Current Circuit: A circuit which is so designed and protected
  that , under both normal conditions and a likely fault condition, the
  current which can be drawn is not hazardous.

# TNV Circuit: A circuit in the equipment to which the accessible area
  of contact is limited and that is so designed and protected that,
  under normal operating and single fault conditions, the voltages do
  not exceed specifying limiting values.
# TNV-1 Circuit: A TNV circuit whose normal operating voltages do not
  exceed the limits for a SELV circuit under normal operating
  conditions and on which overvoltages from telecommunication networks
  are possible.
# TNV-2 Circuit: This is a TNV circuit whose normal operating voltages
  exceed the limits for a SELV circuit under normal operating
  conditions. These circuits are not subject to overvoltages from
  telecommunication networks.
# TNV-3 Circuit: This is a TNV circuit whose normal operating voltages
  exceed the limits for a SELV circuit under normal operating
  conditions. Overvoltages from telecommunication networks are
  possible for TNV-3 circuits. 

# SELV Circuit (Safety Extra Low Voltage): A secondary circuit which is
  so designed and protected that, under normal and single fault
  conditions, its voltages do not exceed a safe value (definatley lower
  than 42.4V peak or 60V d.c).

Aiheesta lis��:
Electrical Safety of Dc Telephone Systems
http://www.ce-mag.com/archive/02/03/lamothe.html

For Europe, telephone-interface requirements are specified in ETSI
standards. Although there are still many country-specific deviations,
ETSI standards are intended to minimize the differences and reduce
duplicated testing.

ETSI 300 001: "Attachments to Public Switched Telephone Network
(PSTN); General Technical Requirements for Equipment Connected to an
Analogue Subscriber Interface in the PSTN." This standard specifies
the requirements for equipment that is connected to the PSTN. For this
standard, the dc supply may be a 48- or 60-V battery. Such equipment,
which often has ring voltage present, is typically supplied with dc
operating power via the telephone line. In this case, the supply
source does not meet the Network Environment 0 requirements. Because
it falls under Network Environment 1, it must be evaluated as a TNV-3
supply, regardless of the input voltage rating. Even if the equipment
uses 60-V dc power (making an operating voltage of 72 V dc), it must
still be evaluated as a TNV-3 circuit. It can't be considered a TNV-2
circuit even if the supply voltage is less than 60 V dc.

ETSI 300 132-2: "Equipment Engineering (EE); Power Supply Interface at
the Input to Telecommunications Equipment; Operated by Direct Current
(dc)." This standard specifies the requirements for systems where the
battery power is supplied by an in-plant dc power source (such as a
battery bank), or an ac power supply with a dc output. The dc supply
may be a 48- or a 60-V battery. In this case, the supply source does
meet Network Environment 0 requirements because it is not normally
exposed to an outside-plant source. As a Network Environment 0, it can
be evaluated as a TNV-2 supply. Even if the equipment uses 60-V dc
power (making an operating voltage of 72 V dc), it is still evaluated
as a TNV-2 circuit because the dc supply is a secondary circuit.


-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/