12. Guidelines for Usage – Piezoelectric Actuators
Piezoceramics are relatively brittle materials. This should be noted when handling piezoelectrical actuators. All piezo elements (also elements with pre-load) are sensitive to shock forces. Piezo elements without pre-load (e.g. series P, elements with lever transmission) should not be used under tensile forces (see also drawing in section 2). Applications in which tensile forces or shear forces occur, should be realized by pre-loaded elements. On request piezo elements can be optimized with integrated or external pre-loads for special applications.
During dynamical uses there can occur internal tensile forces due to the acceleration of the ceramic element itself (see also section 5 dynamic properties). Pre-loaded piezo elements have a top plate with threads. Please note the depth of the treads. Do not apply large forces for fixing screws at the piezo elements.
Actuators are capacitive loads. Do not discharge actuators by short circuiting the leads. Ensure dielectric strength of your power supplies, wiring and connectors to prevent accidental arcing. Abrupt discharging may cause damage to the stacks.
Piezoelectric actuators such as stacks or various piezo elements with lever transmission work as capacitors. These elements are able to store electrical energy over a long time and the stored energy may be dangerous. Connect and disconnect the elements only when the power supply is switched off. Because of piezoelectric and pyro-electric effects, piezo actuators can generate electric charges if there are changes in the external mechanical loads or the temperature of the actuator.
Before you begin to work with any piezoelectrical actuating system, please note:
Switch off the power supply and discharge the actuator properly by setting the supplies to zero. If the actuator is disconnected, use a resistor for discharging the actuator. Do not switch-on the power supply when actuators are disconnected. Be sure that the electrical contact of the operator to the output connectors of the power supply is not possible when the supply is switched on!
Power supplies for piezo elements are developed especially for these elements. Do not use these power supplies for other applications.