10
Explosion protection - device description
The ExResistTel MB serves for making calls within operating facilities in
danger of explosion in the zones: Zone 1, Zone 2, Zone 21 and Zone 22.
The ExResistTel MB telephone is designated to analogue telephone
networks.
The headset, second receiver and external secondary alarm
accessories are not a component of the ExResistTel MB telephone, but
rather can be connected as an option.
The ExResistTel MB telephone has an casing made of electrical-static,
conductive press plant material and a stainless steel keyboard.
The casing consists of a box shaped lower part, in which a tub is
integrated to hold the electronic system, as well as a curved cover with
a keyboard.
The cover is pressed under the medium layer of a surrounding seal with
four screws on the casing lower part and forms the non-secure and
secure connection space. The electronic system conductor board is
located in the tub from the casing lower part, which is completely
embedded in the compound.
Non-secure connection clamps with increased security:
From the casting, a 4-pin connection clamp (See connection diagram on
page 16) comes out in increased security, to connect the non-secure
telephone network (A, B), clamp 13 and 14 as well as for the connection
for an optional, external, explosion protected second alarm (Bell shunt1,
Bell shunt), clamp 15 an 16.
