Installation, operation and maintenance instructions
High voltage flameproof motors for explosive atmosphere
AMD Rg 355-400-450-500
Operations prior to commissioning – Electrical operations
Issued by: MOLM
Sheet No.
3AAM101033 E
Rev. B 01.2023
Page 2 of 3
W
e
reserve
a
ll
rights
in
th
is
docu
ment
an
d
in
the
inf
or
mati
o
n
cont
ai
n
e
d
th
er
e
in.
R
epr
o
duct
ion
,
use
of
disc
losur
e
to
thir
d
part
ie
s w
itho
ut
expr
ess
aut
h
or
ity
is
s
tric
tly
for
bidd
en.
The temperature sensors inserted in the stator
winding have a normal isolation resistance value
around 1000 M
.
DRYING THE MACHINE
If, due to contamination caused by transport
conditions or incorrect storage, the isolation
resistance value is found to be less than the
minimum permissible value for safety of the
personnel
, it becomes necessary to carry out a
drying procedure
The rules for drying electrical machines are
contained in the “Maintenance” section of this
manual. As indicated in that section, the drying of a
motor is an operation during which hot dry air is
circulated inside the motor.
The Ex db motors are completely closed type.
Therefore, to circulate air inside, some parts of the
motor have to be dismantled.
It is important to remember that all the dismantling
and refitting operations on the Ex db equipment are
to be carried out by skilled, qualified experts, so as
to ensure that the explosion proof characteristics are
maintained.
Therefore, it is advised, should this operation be
necessary, to entrust the motor opening and closing
operations to a Service organization that is qualified
to intervene on Ex db equipment.
TEMPERATURE SENSORS INSERTED IN THE
WINDINGS
Usually resistive temperature sensors type Pt100 are
used See the specific technical instructions for any
variants.
The temperature sensors are usually connected to
safety and protection circuits, that, according to the
temperature detected, activate alarm systems or cut-
out the power supply switch The setting of these
safety systems should be regulated at approx. 10°C
over the working temperature with maximum load
and maximum environment temperature
According to the temperature class of the electrical
components of Group II, the setting should be
regulated for the following maximum temperatures:
Temperature class
T3
T4
Alarm: 145°C
140°C
Release: 150°C 145°C
The above limits ensure that the maximum surface
temperature of the machines cannot exceed the
limits of the assigned temperature class (T3 or T4).
For machines supplied by inverter, the limits
indicated are to be reduced by approx. 15°C
to
take into account this heavy duty operating condition.
ELECTRICAL CONNECTIONS
Warning! During the installation operations no
drilling is allowed on the casing and/or covers of
the motor and terminal boxes.
The power supply cables are to be provided so that
the entire installation complies to the current
Standards regarding electromagnetic compatibility.
The use of shielded cables is recommended,
connected to a protective ground circuit.
Motors powered by inverter require special attention.
See the specific inverter technical documentation.
All cable inlets to the terminal box are to be by means
of the cable clamps indicated in the specific technical
documentation.
The installer is responsible for the use of the
correct and certified cable clamps.
CONNECTION TO MAIN TERMINAL BOX
See the connection diagram on the label inside the
box.
Check that the power supply network voltage and
frequency correspond to the values indicated on the
machine ID plate.
The section and type of power supply cables, as well
as the ends for connection to the isolators are to be
adequate for the maximum current draw, and if
values are required that are over the standard
values, also for the indicated fault current.
See the sketches below.
Main terminal box Ex db
The winding terminals are marked with the letters U
- V- W in accordance with IEC Standard 60034-8.
The neutral terminal, if it exists, is marked with the
letter N.
The connection, with the correct phase sequence (L1
– L2 – L3) ensures the direction of rotation as
indicated by the arrows on the coupling side shaft.
If the phase sequence is not correct, the rotation can
be reversed by changing over the connections that
go to terminals U and W.
CONNECTION TO AUXILIARY TERMINALS BOX
There may be one or more auxiliary terminal boxes.
With the standard solution there is a terminal box
fitted with a separator between the power circuit
terminal board (internal heating, fan, etc) and the
measuring and signals circuits terminal board.
See the specific technical documentation for any
variants.
Make sure that all monitoring instruments are
connected as indicated on the diagram and check
they function correctly and that the indications are
correct.
