RZ eta-engl Kopie - HOWATHERM

12
Energie savings and
true output
reporting
Opimized operating
convinience
Air flow measuring
system
Control system: practical advantages
Fan efficiency remains essentially unchanged
throughout the operating
speed range.
A stable fan operating regime is achieved
through the full fan speed range.
Stepless speed changes can be effected
via input signal control.
Minimum and maximum speed levels can
be preset.
Motors may be of standard design.
The need for soft starters is eliminated,
given that the start-up current is limited
to a defined value by the frequency converter.
The additional electrical losses associated
with the frequency converter are low
(approx. 4% at full load).
Control and monitoring systems can be
easily interfaced with the frequency converter
Control parameters facilitate optimum
system adjustment.
A constant volume flow regulation is
provided.
Simple control loops can be implemented
even without higher-order controller
or control system.
System adjustments can be made at the
touch of a button.
Control options
The differential pressure transducers provides
a linearized output signal (0/4-20 mA)
corresponding to the volumetric flow rate.
This output signal is wired at our factory
to the integrated frequency converter. It
will thus serve as a reference signal for the
frequency converter's built-in PID controller
but may also be fed to an external higher-order
control system. The 24 V d.c.
power supply is likewise generated by the
integrated frequency converter.
Following parametrization of the frequency
converter in our factory, the flow rate
can be directly read off the frequency converter's
display in m3 /h. In addition, the air
flow can be kept constant to an externally
defined setpoint via the built-in PID controller.
Via an output signal, the volumetric
flow rate may be transmitted to a higher-order
control system, e.g., for efficiency
optimization. For more detailed information
refer to our HP-WRG system description.
Varying due to changes in filter pressure
drops, dry or wet cooler conditions, mixing
flow mode, etc., will thus be compensated
for by the control system.
HOWATHERM is a member of the German
Federation of Manufacturers of Air
Handling Units (Herstellerverband
Raumlufttechnische
Geräte e.V.)
Practical advantages
The volumetric flow rate measurement
embodied in our ETA SYSTEM helps to reduce
the electrical power consumption
and provides a true output picture, given
that the actual volume flow will correspond
exactly to the target value and no
additional volume loss for conventional
flow rate measurement (e.g., orifice plates,
nozzles) is en-countered. The system is
easier to adjust, requiring just the touch of
a button on the frequency converter. The
specific volume flow is digitally displayed
throughout the adjustment process.