Flameproof motors | 23
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5.
INSTALLATION
Electric motors should be installed in locations of
easy access for inspection and maintenance. If the
surrounding atmosphere contains humid, corrosive
or flammable substances or particles, it is essential
to ensure an adequate degree of protection. The
installation of motors in ambient where there are
vapours, gases or dusts, flammable or combustible
materials, subject to fire or explosion, should be
done in accordance with EN/IEC 60079-14
Standards.
Under no circumstances, motors can be enclosed in
boxes or covered with materials which may impede
or reduce the free circulation of cooling air. Motors
fitted with external cooling must be located at least
50mm from the ground to permit free air circulation.
The air inlet and outlet should never be obstructed
or reduced by conductors, pipes or other objects.
The installation site should permit conditions of air
renewal at a rate of 30m³ per minute for each
100kW motor output.
MECHANICAL ASPECTS
5.1.1. MOUNTING
In order to ensure the adequate operation, in
additional to a stable foundation, the motor must be
precisely aligned with the coupled equipment and
the components mounted on the shaft end must be
properly balanced.
As requirement, the motor base must be flat and
follow the guidelines of standard DIN 4024-1:
“Machines Foundations – Flexible Structures that
Support Machines with Rotating Elements”.
NOTICE:
With the machine mounted and coupled, the relation
between the foundation natural frequency and:
- The motor speed frequency;
- The double speed frequency;
- The double line frequency.
Must be as specified according described bellow:
Foundation natural frequency of the 1
st
order:
-
+25% or
-20% in relation to the above
frequencies.
Foundation frequency of higher order:
-
+10% or
-10% in relation to the above
frequencies.
ATTENTION
The customer must guarantee that
the
foundation
respects
the
frequencies defined in this manual.
5.1.2. FOUNDATIONS
The motor base must be level and free from
vibrations. For this reason, concrete foundation is
recommended.
The type of base to be built will depend on the
nature of the soil at the installation site or on the
floor capacity.
When designing the motor foundation, it must be
taken into consideration the fact that the motor
might, occasionally, be submitted to a torque higher
than the rated torque. If such designing is not
correctly made, vibration problems can occur to the
unit (foundation, motor and driven machine).
NOTE
On the concrete base, a metallic
plate to support the leveling bolt must
be provided.
Based on Figure 5-1, the forces over the foundation
can be calculated by the following formulas:
)
(
max)
4
(
.
.
.
5
.
0
1
A
C
g
m
F
)
(
max)
4
(
.
.
.
5
.
0
2
A
C
g
m
F
Where:
F1
and
F2
- Forces on the base (N).
g
- Gravity acceleration (9.81m/s²).
m
- Motor mass (kg).
Cmax
– Maximum torque (Nm).
A
- Taken from motor dimensional drawing (m).
Figure 5-1 - Schematic of foundation loads