4
e motor protection is IP44, insulation class F. e win-
dings are protected against moisture by additional impreg-
nation. e motors are characterized by a relatively low
inrush current.
Electric instalation
e electrical installation of the fan itself is terminated by a
special non- explosive terminal block with IP 66 protection.
e connection diagrams of the electric motor are in a se-
parate chapter Electrical installation.
Attention! Electric motors must not be connected in a
delta. ey are always connected only to the star (for
nominal voltage 3x400V / 50Hz or reduced voltage).
Electric motor
protection
For all motors, continuous
monitoring of the internal
motor temperature is provi-
ded as standard. e internal
temperature is sensed by
miniature temperature sen-
sors, thermistors, which are
stored in the winding of the
electric motor. e thermis-
tors must be connected to
an ATEX-certified thermistor
relay (approved type II (2)
G), which must be located outside potentially explosive
atmospheres. e relay at 130 °C irreversibly opens the
control circuit (contactor switching circuit) meeting the
operating conditions in the relevant zone 1 or zone 2. For
the design, selection and installation of electrical installa-
tions in explosive atmospheres, the specific requirements
of the ČSN EN 60079-14 standard must be respected. e
method protects the motor against operationally unfavo-
rable influences - for example against overload, failure of
one phase of the network or short circuit, firm braking of
the motor, interruption or short circuit of the protection
circuit, high temperature of the transported air. ermal
protection with proper connection is comprehensive and
reliable. ermistors of up to two fans can be connected to
one thermistor relay, but they must be connected in series.
In such a combined connection, it must be borne in mind
that in the event of a failure of one electric motor, both fans
will be stopped.
Attention! It is not permissible to protect the electric
motors of the fans with conventional current-depen-
dent protection with motor overcurrent protection
elements!
Fan Output Control
For fans, several control methods can generally be used,
but for RP Ex fans, voltage control is the most suitable. e
fan output can be fully regulated by changing the speed.
e speed changes as the voltage at the terminals of the
electric motor changes (decreases). RP Ex fans are conti-
nuously adjustable if the voltage change is continuous. In
practice, step voltage regulators are more oen used. e
voltage must not increase above the nominal value accor-
ding to the label value and the current must not exceed the
nominal value of the fan electric motor.
Attention! It is not permissible to control the speed of
the electric motor of the RP Ex fan with a frequency
converter!
5-stage voltage regulation
Voltage regulation of Vento fans is technically and opera-
tionally the most advantageous. ere is no danger of in-
terference, there is no humming, whistling and vibration of
the motor, voltage- regulated motors become less hot. e
voltage regulators TRN and TRR can be used to regulate
the fan power in 5 stages with a step of about 20%, which
corresponds to 5 curves of pressure versus flow in the ope-
rating characteristics of each fan. e electric motors of RP
Ex fans can be operated in the range of 25% to 100% of
Technical details
Table 1 – correlation of voltage and regulation
the rated voltage. Table 1 shows the relationship between
the controller output voltage and the set power stage. Ex
fans are only supplied with three-phase electric motors.
ree- phase TRN or TRRD controllers are used to regulate
their speed or power. TRN controllers are manufactured in
four types according to the current value of TRN 2D, TRN
4D, TRN 7D and TRN 9D. An important feature of this se-
ries is the possibility of remote control by manual control
ORe 5, or automatic switching of 5 stages by control OXe
depending on the external control signal 0 to 10 V). e
simpler TRRD controllers are also available in four sizes,
TRRD 2, TRRD 4, TRRD 7 and TRRD 9. ese controllers
ncannot be controlled automatically or remotely (therefore
they require location within easy reach) and do not include
fan protection (must be fully secured by other equipment).
Attention! No other type of control is permitted!
Accessories
RP Ex fans form part of a wide range of elements of the
Vento modular ventilation and air conditioning system. By
selecting suitable elements, any air handling unit can be
assembled for simple ventilation and complex comfort air
conditioning. When designing individual devices, it is nece-
ssary to keep in mind for which environment the devices
are intended. An approved type of thermistor relay can be
ordered together with the fan for thermal protection of the
fans.
Figure 4 – thermistor
ree-phase
electric motor
Characteristic curve - regulator stage
Voltage (V)
