DWEX DIGITAL LOUD-SPEAKING EXPLOSION PROOF CALL STATION
User Manual
armtel.com
page 19/40
© Armtel
protection are ensured by the use of Ex-cable glands having the necessary certificates.
The box covers are protected from self-unscrewing by means of locking screws.
1.5.4
Explosion protection type "ib"
is provided by limiting the parameters of the
electrical circuits to intrinsically safe values, which meets the requirements of
EN 60079-11:2012).
Blocks of spark protection on zener diodes, in conjunction with current-limiting
resistors, limit the voltage and current in the electrical control and power supply circuits and
circuits in emergency mode to the safe level specified in EN 60079-11:2012.
In signal and power supply circuits, taking into account the emergency operation of
the product, uninterruptible current-limiting resistors are used, which ensures a reduction in
the maximum dissipated power of the circuit elements to a safe level (not more than 2/3 of
the rated value).
Printing, design and electrical wiring are carried out in accordance with
the requirements for leakage and electrical gaps in accordance with EN 60079-11:2012.
Elements of the design, which can be in direct contact with the user during operation,
(direct call keys, plugs), are made of antistatic material.
1.5.5 Ex cable glands used in DWE
х
have certificates confirming the type of explosion
protection for the product enclosure and the explosion-proof shell. The temperature range
for the Ex-cable glands equals or higher than the temperature range for DWEx unit.
Protection rate of the Ex cable glands of the enclosure as per GOST 14254-2015,
EN 60529:1991/A2:2013 is no less than the protection rate of DWEx unit.
1.5.6 Explosion-proof marking as per EN 60079-0:2012 –
«II 2 G Ex db eb ib IIC T6
Gb» and «II 2 D Ex tb IIIC T85°C Db IP66»
.
1.5.7 Requirements for protection from static electricity of non-metallic parts of the
product
The surface coating consists of an adhesive primer spray on plastic and acrylic enamel
with the addition of antistatic materials. The surface resistance of the coating is from 1 to
1000 mOhm.
