Background
Recently, we have replaced 8 sets of staircase pressurisation control panel and their remote monitoring panel for a boarding school. This pressurisation staircase system is required by SCDF, used during an emergency such as fire. During a fire, occupants in the building will use this pressurised staircase to escape, the pressure in the staircase keeps out the smoke allowing for safe exit.
For more information about SCDF Clauses, refer to the hyperlink : https://www.scdf.gov.sg/firecode/table-of-content/chapter-7-mechanical-ventilation-smoke-control-systems/clause-7.2
PID Control
In each system, the 7.5kW exhaust fan is powered by a Variable Speed Drive (VSD) in our local control panel. This VSD ties in with the differential pressure transmitter to achieve PID control. The transmitter will sense the pressure of the staircase and compare with atmospheric pressure, this would be transmitted in 4-20mA to the VSD. If the staircase pressure drops, there will be a higher signal e.g. 12mA to 20mA sent to the VSD and the VSD will accelerate the exhaust fan according to the current received. Conversely, the transmitter sends a lower signal e.g. 4mA to the VSD when the required pressure is achieved.
Fire Operation
During a fire, the fire alarm panel will send a signal to the remote monitoring panel (Shown Below) and the remote monitoring panel will send a command to run all the local control panel.
HMI Remote Monitoring Panel
Above shown is the remote monitoring panel at the security post, it receives and commands the 8 local panel at the rooftop. This system is upgraded to a HMI touchscreen with 3 pages, allowing for more features and recording functions for the user. Also, we catered an additional ethernet switch for the user to link to a command center PC in future. This HMI screen can be displayed onto a PC web browser.
Page 1
– Remote status (RUN, STOP, TRIP) , AUTO-BYPASS switch, Fire Alarm light, Fire Mode Reset button, Alarm List
Page 2
– System alarm history (Occurrence, Message, Recovery Time, Confirm Time)
Page 3
– System diagram animation, total running hours of individual fan