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Siemens D 83.1 · 2016
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Motors with Explosion Protection
Orientation
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Overview
(continued)
Types of protection
Type of protection "Non-sparking" Ex nA
acc. to IEC/EN 60079-15
For motors with type of protection "Non-sparking", the type of
construction prevents the occurrence of arcing, sparks or hot
surfaces during normal operation. Motors of this type of
protection are occasionally located in a potentially explosive
atmosphere whereby the atmosphere can achieve a level that
poses a risk. These motors are assigned to device group II –
category 3G (corresponding to Zone 2).
The LOHER CHEMSTAR and LOHER VARIO Ex nA series are
generally certified for the highest class "IIC". They are marked in
accordance with the EC directive (2014/34/EU) with II 3G Ex nA
IIC T3 Gc. Compliance with the regulations is documented with
an EC Declaration of Conformity.
The motor terminal boxes are also marked and certified as
"Non-sparking". The terminal boxes of the LOHER CHEMSTAR
and LOHER VARIO Ex nA series are identical in construction to
the Ex e "Increased safety" connection system. In accordance
with the current, harmonized edition, EN 60079-0, the gas for the
type of protection test must be specified in the case of type of
protection "Non-sparking".
Type of protection "Explosion-proof enclosure" Ex d
acc. to IEC/EN 60079-1
For motors in type of protection "Explosion-proof enclosure", it is
ensured that any explosion will be restricted to within the motor.
The enclosure must resist the pressure of the explosion and also
prevent ignition from the internal to the external atmospheres.
Motors in type of protection "Explosion-proof enclosure Ex d"
are used in a potentially explosive atmosphere whereby this
atmosphere can achieve a level that poses a risk. These motors
are assigned to device group II – category 2G (corresponding to
Zone 1). They ensure a high degree of safety.
To define the risk posed by a potentially explosive gas, the
minimum ignition temperature of a dust cloud is required as well
as details of the possibility of a flame exiting through a narrow slit
in the motor enclosure. This is achieved by classification in
explosion groups IIA, IIB and IIC, whereby IIC represents the
highest requirements (see the table "Assignment of combustible
gases and vapors").
LOHER CHEMSTAR Ex d(e) motors
The LOHER CHEMSTAR 1PS5 motor series in type of protection
Ex d(e) are approved for use in potentially explosive atmo-
spheres of Zone 1 according to EN 60079-0, EN 60079-1
and EN 60079-7. They are marked in accordance with the
EC directive (94/9/EC) with II 2G Ex d IIB T3-T6 Gb and
II 2G Ex d IIC T3-T6 Gb. If the terminal box is in type of protection
"Increased safety", they are marked with II 2G Ex de IIB T3-T6 Gb
and II 2G Ex de IIC T3-T6 Gb. Compliance with the regulations
is ensured in every case with an EU type-examination certificate.
SIMOTICS XP motors
The SIMOTICS XP 1MD5 motor series are positioned in the
range of explosion-proof motors alongside the LOHER motor
series and represent the future standard product series.
SIMOTICS XP motors are characterized by significantly shorter
delivery times, as well as by a considerable simplification of
order processing, but in comparison to the 1PS5 motor series
the variety of products is limited and the product characteristics
are fixed. The components with relevance for the type of
protection, such as enclosure, bearing plate and terminal box,
are identical in design in the 1MD5 and 1PS5 motor series.
These two series are therefore mechanically interchangeable
and offer a well-rounded portfolio ranging from 1MD5 standard
applications to 1PS5 special applications.
The SIMOTICS XP 1MD5 motors are explosion-proof,
3-phase induction motors with squirrel-cage rotors. They are
suitable for use under ambient conditions in which there is a high
risk of an explosive atmosphere being generated as a result of
gas, vapor or mist (Zone 1). The motors comply with directive
ATEX 94/9/EC and are marked with II 2G Ex de IIC T3-T6 Gb.
Type of protection "Dust explosion protection" Ex t
acc. to IEC/EN 60079-31
The motor series in types of protection "Non-sparking" and
"Explosion-proof enclosure" already described can also be
designed for dust explosion protection. Atmospheres with
potentially explosive dust are classified as frequently occurring
(Zone 21) and rarely occurring (Zone 22). Further classification
differentiates between conductive and non-conductive dust.
In general, motors of the 1PS and 1MD5 series can be used in
Zone 21 for non-conductive and conductive dust and in Zone 22
for non-conductive dust. The motors are marked in accordance
with EN 60079-0 and EN 60079-31 with II 3D Ex tc IIIB T130 °C
Dc (Zone 22, non-conductive dust) or II 2D Ex tb IIIC T130 °C
(Zone 21, conductive dust). The installed terminal boxes are
marked and certified in accordance with the dust and gas
explosion protection class.
Suitability of the motors is confirmed for Zone 21 with an
EU type-examination certificate and for Zone 22 with an
EU Declaration of Conformity.
Motors with dual labeling for gas and dust may only be used in
applications in which gas and dust occur simultaneously after
prior examination of the properties of the hybrid mixtures by the
user.
For further information, see Chapter "Operation of motors with
type of protection "Dust explosion protection"".
Changes to the Ex marking
In accordance with the latest edition of the standards for the
"Explosion-proof enclosure" and "Increased security" types of
protection, there is a change to the device marking. The type
of protection "Non-sparking" Ex nA acc. to IEC/EN 60079-15
has been integrated into the latest edition of the standard for
"Increased safety" according to IEC/EN 60079-7 as Ex ec.
This has the following effect on the Ex marking:
•
"Increased safety" for Zone 1 and Zone 2 (previously Ex e):
II 2G Ex eb IIC T3 Gb
•
"Increased safety" for Zone 2 (previously Ex nA):
II 3G Ex ec IIC T3 Gc
•
"Explosion-proof enclosure" for Zone 1 and Zone 2
(previously Ex d): II 2G Ex db IIC T4 Gb
After the end of a transitional period, the new editions of the
standards are to be applied with the changed Ex marking.
The transitional period for "Explosion-proof enclosure" ends on
August 1, 2017, whereas the transitional period for "Increased
safety" and therefore also "Non-sparking" ends on July 31, 2018.
There are no changes for the user other than the device marking.
© Siemens AG 2016