MD9822

Manual Call Point

The MD9822 is an automatic addressable Manual Call Point designed for dry areas with an IP22 protection grade. It features direct type activation, eliminating the need for tools or hammers. The fire alarm is triggered when the operator deforms the front plate by pressing it with a finger. Resetting the alarm requires a specific tool inserted into a dedicated slot.

Upon activation, the device closes a switch contact, and the signal is processed by a conditioning circuit before reaching the microprocessor. The software includes a routine to filter out transient signals and external disturbances. Communication with the Central Unit occurs through LCU or BCU control cards, providing 24Vdc power and modulating a serial transmission signal via the MD2 protocol through the Loop. The device address is programmable by the Central Unit.

In Degraded Mode, activated by a Central Unit fault, an optical signal (red LED) flashes when an alarm is detected. The enclosure is made of red thermoplastic material, assembled by interlocked parts. The internal electronic board is protected by conformal coating for high reliability.

The TOD (Test on Demand) feature allows on-demand functionality testing initiated by the Control Unit. This includes checking the alarm activation circuit and LED functionality. TOD ensures automatic tests with minimal manpower, enhancing the overall reliability of the Fire Detection System.

The Manual Call Point includes a short-circuit isolator to protect the loop from short-circuits. It opens the loop connection when the absorption current exceeds a set value, isolating the affected area and maintaining functionality in the remaining branches. Two LEDs indicate the side of the loop with the short circuit, and the isolator’s status is transmitted to the Control Unit, aiding in identifying system points without accessing the terminal board.