5
2.8 IP Protection and designation
The housing for the MT-series transmitters is certified as con-
forming to protection type IP67 (according to IEC 60529) or Type
4X (according to NEMA 250).
2.9 Cable connection
The electrical connection is established via a cable entry, ½-4
NPT thread, or by M20 adapter.
2.11 Protective grounding
All transmitters are supplied with an external ground connection for
protective grounding. Wire this ground connection to a suitable earth
ground. For a transmitter measuring loop, an earth ground should
maintain a resistance of 5 ohms or less. Use a heavy-duty conductor, at
least 15 AWG / 1.6mm2 Ø.
IMPORTANT NOTE
With Category 3 transmitters for use in “Zone 2”, a
qualified cable gland for this type of protection must be in-
stalled by the customer (see the Hazardous Area Consideration
section). For transmitters with a flame-proof enclosure (Ex d)
type of protection, the housing cover must be secured using
the locking screw. The screw plug that may have been supplied
with the transmitter must be sealed at the plant using Molykote
DX. The installer assumes responsibility for any other type of
sealing medium used. Increased force is required to unscrew
the housing cover after an interval of several weeks. This is not
caused by the threads but is due to the type of gasket.
CAUTION
• The cable entry device shall comply with the require-
ments of EN 60079-0 and maintain IP 54 or better as required by
the installation conditions.
• Field wiring should be rated at least 10°C above the maximum
ambient temperature
2.10 Grounding
A terminal is available on both the outside of the housing and in
the plug for grounding (PE) the transmitter. Both terminals are
electrically connected to one another (see Figure 2-12).
Figure 2-12 — Ground connection on transmitter housing
Ground
Screw
WARNING – General Risks.
A protective grounding connection is absolutely
necessary to ensure personnel protection, to protect
against surge (in case of installation of this option) and to pre-
vent explosions in potentially explosive environments.
2.12 General guidelines
WARNING
Make sure all circuits are de-energized prior to
installation.
The MT-series has been evaluated as an Installation (Over-
voltage) Category 1/Pollution Degree 2 apparatus, per IEC
61010
The maximum altitude of operation is 6560 feet (2000 me-
ters).
The MT-series is designed with both internal and external
protective earth (ground) terminals.
All field wiring connected to the MT-series transmitters must
comply with National Electric Code or any other applicable
regional electric codes.
2.13 Flame-proof/explosion-proof installations
2.13.1 Installation requirements
The MT-series of level transmitters is designed for use in Division 1
or at the boundary of a Zone 0 and Zone 1 hazardous area.
CAUTION
The flameproof joints of the equipment are not intend-
ed to be repaired. Consult the manufacturer if repair of the
flameproof joints is necessary.
CAUTION
• The cable entry device shall comply with the requirements of
EN 60079-0 and maintain IP 54 or better as required by the
installation conditions.
• Field wiring should be rated at least 10°C above the maximum ambi-
ent temperature
Cable or conduit entries must be fitted with a suitably certified cable
entry device, with or without the use of a suitably approved thread
adaptor. Where conduit is used in the installation, a conduit seal is
not required immediately after the end-user field wiring entrance.
Installation and use of apparatus in hazardous locations shall be in
accordance with an IEC 60079-14 or applicable regional standards.
CAUTION
The housing cover can only be removed when the unit
is installed in a non-hazardous area, when installed with intrinsic
safety barrier, or when power is removed from the transmitter.
WARNING – Bodily Injury.
General risks. Cable, cable gland and unused port
plug must be in accordance with the intended
type of protection (for example, intrinsically safe and explo-
sion-proof) and the degree of protection (for example, IP6x
according to IEC EN 60529 or NEMA 4x). See also the adden-
dum for Ex Safety Aspects and IP Protection. In particular, for
explosion-proof installation, remove the red, temporary plas-
tic cap and plug the unused opening with a plug certified for
explosion containment.
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