Page 67 - Industrial Plants

Accessories for connecting

flame-proof motors

Connection of “Ex- db” electric engines with “Ex- db” connection
box to the power line using electrical connection accessories

Andrea Battauz, R&D Manager
Cortem Group

ncreased safety electric motors or flameproof
electric motors with increased safety
connection box, which facilitate the
connection of this equipment to the power
line, have been on the market for many
I years. These very common motors are often
chosen by many designers.
In this article we will delve into the connection of
“Ex- db” electric motors with “Ex- db” connection
box to the power line using electrical connection
accessories, such as adapters, conduit sealing
devices, cable glands and flexible tubes.

“Motors completely made in
explosion-proof protection are Figure 1 : Conduit tubes with single-core cables inside them
still widely used and very present
in plants. They are increasingly
accompanied by increased safety ‘Ex- protective tubes, commonly known as conduit
eb’ engines or ‘Ex- db’ engines, with system, are very common. Single insulated wires are
an enclosure with ‘Ex- eb’ increased usually laid inside these pipes, as in Figure 1.
safety connection terminals

In Figure 2, we see the connection of a motor with
In this regard we will give some examples of flameproof connection box. To prevent a possible
system applications, remembering that the choice explosion inside the flameproof equipment from
of these accessories, as is the case for cables, is spreading to the system, a conduit sealing device
the responsibility of the designer who must was used [2]. Another important connecting element
scrupulously apply what is foreseen by applicable is the three-piece unions. This adapter can be used
edition of IEC/EN 60079-14 [1]. to give the right inclination to the sealing fittings,
necessary for pouring and filling resin inside. Finally,
the connection with the system in metal ducts is
Connection to a plant with made with a flexible tube which, while maintaining

conduit system high mechanical protection, allows the transmission
of vibrations produced by the machine in operation
In sites classified as at risk of the presence of to be reduced. It is a good rule to prevent any
explosive atmospheres, systems with metal vibrations produced by the machine from being

IndustrIal Plants - May 2024
65