Integrative notes to the operating manual for magnetic coupling centrifugal pumps conforming to the ATEX 94/9/CE directive TCK... - TBK... – TBAK…
11
5.3 – ELECTRIC CONNECTIONS
The electric connections for powering the motor and any of its additional instruments must only
be carried out by skilled and authorized persons who must observe the instructions of the
manufacturer of the motor and of the electric appliances and the national provisions in force.
This refers particularly to the selection of components correctly certified according to the ATEX
94/9/EC Directive for a level of safety equal or higher than that of the pump.
POMPETRAVAINI absolutely cannot be held responsible for any damage to persons or objects
in relation with the electric appliances installed on the pump but not purposely authorized or
with errors when making the electric connections.
OBSERVE THE SAFETY PRESCRIPTIONS SHOWN IN CHAPTER 2 OF THE OPERATOR’S
MANUAL.
ANY JOB ON THE UNIT MUST BE CARRIED OUT WITH THE ELECTRIC POWER SWITCHED OFF.
RESIDUAL RISK: Any incorrect electric connections may generate sparks or high temperatures
which may ignite the potentially explosive atmospheres present. Therefore, maximum care must
be applied during
installatin
so
as
to avoid any false contacts, overloads, etc.
When carrying out the electric connections for powering the motor, always check the
direction
of rotation in order to
avoid wrong rotation of the pump impeller. The correct
direction
of rotation is shown by the red arrow on the pump body
(Fig. 1)
. The instructions for checking the
direction
of rotation are shown in Chapter 8 of the Operator’s Manual.
To guarantee better starting conditions to the pump and long l
ife
of the magnetic coupling it is
strongly recommended the use of a soft start system. The use of this kind of system, if duly installed,
allow
s
to reduce the risk of losing the synchronism between the two parts of the magnetic coupling.
RESIDUAL RISK:
Due to
mistaken or sudden start and stop
of the pump
, strong
vibrations
could be generated
due to the magnetic field of the coupling
resulting in
impact or
break-up of components.
If the electric motor combined with the pump is supplied completely by POMPETRAVAINI, the instruction Manual
supplied
by the motor manufacturer is always enclosed. The connection of the electric motor must be carried out
according to the instruction manual of the motor manufacturer. This manual must be carefully preserved together
with the one of the pump. If the manual for the electric motor is not available when carrying out the
connections, please contact POMPETRAVAINI.
5.4 -
DIRECTION
OF ROTATION
The impeller of the pump must
NEVER
turn into the opposite
direction
. The correct
direction
of rotation is shown
by the red arrow on the pump body
(Fig. 1)
. After having completed the installation of the pump inside of the plant and
after having carried out all the necessary connections, check the pump for the correct
direction
of rotation. For this
purpose, use all the necessary precautions. The same steps must be carried out similar to the ones for a pump start-
up. For further information refer to paragraph 11.1 in Chapter 11 of the Operator’s Manual and to the operator’s
manuals of the plant where the pump has been installed, if such manuals are available. The instructions for checking the
direction
of rotation are shown in chapter 8 of the Operator’s Manual.
In order to avoid that the liquid in the delivery
pipe
of the pump flow back due to specific situations of the plant and the
pumps not
rotating
in the opposite direction, a non-return valve must be installed inside of the pump delivery
pipe
. The
installation of a non-return valve serves also for preventing any effect of water-hammer which may occur when the
pump stops. The instructions for installing the non-return valve are shown in Chapter 9 under paragraph 9.2.2 of the
Operator’s Manual.
The correct
direction
of rotation of the standard pumps series TCK and TBK is clockwise if seen
from electrical motor side, while is counter clockwise for the series TBAK, always seen from the
electrical
motor side.
RESIDUAL RISK: The rotation of the impeller in the opposite direction to the foreseen one may
cause unscrewing of the
impeller
lock-nut and therefore cause impacts, frictions and
overheating between the impeller and the pump body, even complete jamming of the pump. Also
the electric motor is subject to a higher power input and overheating. This influences also all
components of the electric power cable which may break, become overheated, create sparking
and burning if not correctly
sized
or installed.