Eaton MTL7700 Instruction Manual page 8

Item Refer to
no . section:
1 3.1 Before beginning installation, check that
the safety documentation confirms that the
proposed system is fully certified (if applicable)
and complies with the recommendations
contained in the relevant sections of IEC
60079-14 for the gas group, temperature
classification and area classification required.
2 4.1/6.2 Make sure the barriers are of the correct
type and polarity as specified in the safety
documentation.
3 4.1 Make sure all barriers are mounted the right
way round and are properly attached so that
the essential earth contact is made securely
in accordance with the safety documentation
and in compliance with the recommendations
of IEC 60079-14.
4 5.3/6.2 Measure the resistance between the barrier
earth DIN-rail and the main power system
earth and make sure it does not exceed the
maximum permitted resistance specified in
the safety documentation.
5 4.1/6.2 Inspect
between the barriers and the hazardous-area
equipment, making sure the cables are the
type specified by the safety documentation
and that they are connected to the correct
terminals.
6 5/6.2 Make sure all hazardous-area cables are well
secured and are segregated from all other
cables.
7 5 Make sure the permitted cable parameters
for hazardous-area circuits are not exceeded
(see relevant certificate or INA7700).
8 5 Make sure all hazardous-area apparatus
and cables are either earth-free or correctly
bonded with an equipotential conductor.
9 5.3/6.2 Make sure all hazardous-area cables and
cable screens are terminated correctly,
the latter preferably via earth foot on the
hazardous side of each barrier or via ERL7.
10 5.4 Make
cables are terminated by a dummy barrier
(MTL7799), earth rail (ERL7) or otherwise
safely connected to earth.
11 Make sure all hazardous-area energy-storing
devices are independently and appropriately
certified.
12 4.1/ Inspect all tagging or identification labels and
4.3.5/ make sure they relate to the correct barrier
4.3.6 types, polarities and circuit loop numbers.
13 5/6.2 Inspect carefully all cables connected to the
safe-area equipment and make sure they are
connected to the safe-area terminals of the
barriers.
14 5.3 Make sure that no safe-area equipment
is supplied from (or includes) a source of
potential with respect to earth that exceeds
250V rms or 250V dc under normal or fault
conditions unless specifically permitted by
the safety documentation.
Note: One phase of a 3-phase supply of up
to 440V is permitted as its value is equivalent
to 250V rms.
15 Make
adequately against moisture, dust, dirt,
vibration, excessive temperatures, physical
damage and unauthorised modifications
Table 2: Safety checklist
INM 7700 Rev 12
Action
carefully all cables connected
sure all unused hazardous-area
sure all barriers are protected
Hazardous-
area
terminals
Product top label
Top label background colour codes
Red =
Black =
Grey =
White =
Orange =
Figure 4: Dimensions (mm) of an MTL7700 range of barrier
Tagging accessories
Power links
4 .3 .1 DIN-rail (THR2 and THR7000)
Eaton can supply both standard (THR2) and plated (THR7000) low-
profile T-section DIN-rail. Although standard DIN-rail maintains
a high-integrity earth in normal conditions, for aggressive
environments Eaton provides THR7000 nickel-plated DIN-rail. Both
types are supplied in 1m lengths for cutting to size as necessary.
Although there is no strict requirement for the DIN-rail to be isolated
from earthed surfaces, it is advisable, in order to minimise the
possibility of the earth circuit being invaded by fault currents which
might interact adversely with other systems. ISP7000 insulating
spacers are a convenient method of insulating the DIN-rail. It is
much easier to install insulating spacers during the initial build, than
to discover later that an equipped and running installation must be
modified.
4 .3 .2 Insulating spacers (ISP7000)
When used, ISP7000 insulating spacers are attached to each end
of the DIN-rail and at intervals depending upon the length of the rail.
It is recommended that spacers be mounted at 300mm intervals
on low-profile (7.5mm) DIN-rail and at 500mm intervals on high-
profile (15mm) rails – see figure 8. The spacers are provided with
suitable screws for attaching to both the DIN-rail and the mounting
surface, which will need to be suitably drilled and tapped for the
purpose. Install each spacer as follows (figure 9):
a) On the mounting surface, drill and tap two holes for M4
screws.
b) Attach the spacer to the surface with the two M4 x 16 screws
provided.
c) Drill an M6 clearance hole (6.5mm) in the centre of the base of
the DIN-rail (if not already suitably slotted)
d) Attach the DIN-rail to the spacer with the M6 x 16 screw
provided.
4
Safe-area
terminals
105
Installation and approval side label
Colour-coded top label
12.6
positive barrier
negative barrier
ac barrier
dummy barrier
power feed module
Section 4 .3 .5, 4 .3 .6
Section 4 .3 .7, 4 .3 .8