5. Special features
Analog amplifiers from US EuroTek, Inc. show some special features, which
are very useful for the operation of Piezoelectric actuators:"Offset"
The amplifiers are provided with a potentiometer where a DC-output voltage can be manually
set over the full operating range. In this mode, the amplifier can be used as an
adjustable voltage supply without the application of an external signal.
When an external signal is amplified, the "Offset voltage is superimposed
automatically. This is useful, when the signal generator produces only bipolar signals
which have to be shifted to get the unipolar signal required to drive Piezoelectric
elements effectively.
"Amplitude"
Using this potentiometer, the input signal can be adapted to the working range of the
amplifier. It is possible to use signal levels 5 V as well as 10 V (e.g. from standard D/A
converting units).
Current booster
Higher power amplifiers such as the LE types are provided with a current booster, which
enable the amplifier to produce a much higher current (for a limited time) than the long
term average current. In this mode, the amplifier is optimized for high power efficiency
when a capacitive load such as a Piezoelectric actuator is operated.
The current booster reduces further the risetime, when rectangular signals are applied.
For these amplifiers the risetimes for a variety of loads are tabulated in the datasheet.
Monitor output
The average output voltage is shown on the front display of the amplifiers.
Realtime signal monitoring is done by the "Monitor -output, which represents the
actual power output status by a 1:100 ratio low power signal. The monitor-output is used
for realtime representation via an oscilloscope. Further it can be used as a signal source
for any control arrangement (feedback control, voltage limitation), where information
about the current status of the actuator is needed.
| 6. Safety Instructions During
operation of Piezoelectric actuators voltages and electrical currents are present which
may be harmful to the operator
· Installation and operation of actuators and electronics supplies must be carried out
by authorized personal only
· All electrical installation of electric supplies, cables and connectors must be
carried out according to standard safety regulations
· Piezoelectric actuators can show large electrical capacitances, and charged
actuators can store electrical charge at high voltage levels, even for long times after
being disconnected from the power supply.
When large volume actuators are not in use, discharge them carefully, and hold them
short-circuited.
· Piezoelectric actuators can generate electrical charge at high voltage levels, when
varying load or temperature is acting on actuators with open leads.
When large volume actuators are not in use, discharge them carefully, and hold them
short-circuited.
· Take care when opening amplifiers and pulsegenerators. High voltage levels can be
held for a long time after disconnecting the devices from line due to large capacitance
internal capacitors. If these devices must be opened, wait at least 15 minutes after
disconnecting them from line. Complete discharge of the internal capacitors has to be
ensured by short-circuiting via a proper resistor. |
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