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Type 2721

Type 2721
2Pages

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PRODUCT DATAPower Amplifier — Type 2721 Power Amplifier Type 2721 has been designed to drive Modal Exciters Types 4826, 4827 and 4828, but can be used with any vibration or modal exciters requiring a 1250 VA power amplifier. USES • To drive Modal Exciters Types 4826, 4827 and 4828 safely to full force rating • To drive any modal or vibration exciter requiring a 1250 VA power amplifier FEATURES • 1250 VA power output • Adjustable RMS output-current limit • Low or high output impedance • Low distortion over wide frequency range • Extensive built-in protection, including interlock • Rear panel voltage and current monitor points • Front panel indicator lights (LED type) showing clipped output signal, temperature overload, current overload, output signal phase (0° or 180°), operating mode (current or voltage), current state and interlock input disabled • Multifunction display (backlit LCD type) showing approximate output current and output voltage • When used with Types 4827 and 4828, powers DC Static Centering Unit Type 1056 and Field Power Supply Type 2830 Description Power Amplifier Type 2721 has been designed to drive Modal Exciters Types 4826, 4827 and 4828, but can be used with any 4 Q vibration or modal exciter requiring a 1250 VA power amplifier. The power amplifier has a useable frequency range from 40 Hz to 10 kHz (full capacity) or DC to 50 kHz (reduced capacity). The rated AC output is 1250 VA into a 4 Q exciter or resistive load, in the frequency range DC to 15 kHz (± 0.5 dB). Harmonic content of the output is very small as heavy negative feedback is used. The instrument can tolerate temperature and supply line variations while maintaining excellent stability. Type 2721 can be used as a voltage generator with low output impedance and a flat voltage frequency response, or as a current generator with high output impedance and a flat current frequency response. The RMS output-current limit is adjustable. For proper functioning, Modal Exciters Types 4827 and 4828 require Power Amplifier Type 2721 together with Field Power Supply Type 2830 and DC Static Centering Unit Type 1056. The picture above shows Type 2721 front and back. Protection Power Amplifier Type 2721 features extensive protection circuits for itself and the connected vibration exciter. When triggered, the protection circuits disconnect the input signal and a LED lights up, indicating the reason for the instrument shutdown. Overload protection against excessive coil current is provided by setting the RMS output current to between 1 A and 18 A. This feature enables Type 2721 to safely drive modal and vibration exciters, with different maximum current ratings. The signal to the exciter is switched off if the preset current limit is exceeded, and the red current LED lights up. The power output stage is protected by a temperature-sensing safety device to prevent output transistor temperatures that ex- Briiel & Kjser

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perature-protection circuit blocks the amplifier input signal, lighting up the red temperature LED. Further protection is provided by an interlock relay that disconnects the input if the operator switches between voltage mode and current mode during operation of Type 2721. Resetting after current, temperature and interlock shutdown is made by simply turning the amplifier gain control fully anticlockwise. POWER OUTPUT CAPACITY: 1250VA into a 4 Q exciter or resistive load, at 25°C and nominal mains voltage (8-pin Neutrik SPEAKON socket at rear panel) OUTPUT VOLTAGE CAPACITY: 71 V RMS, DC to...

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Type 2721 2Pages

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Type 2721
2Pages