The Plena Voice Alarm System employs a simple and easy-to-use method of loudspeaker surveillance based on impedance measurement. On long wire runs, external influences, such as cable capacitance and speaker impedance, can negatively influence the reliability of the measurements. The dummy loads provide a filtered load exclusively at the pilot tone frequency. This greatly increases the dependability of impedance measurements, providing reliable break or short circuit detection, even on long wire runs.
