Changes between Initial Version and Version 1 of ControlLogicFeatures

Timestamp:

12/14/07 11:46:08 (18 years ago)

Author:

anonymous

Comment:

--

ControlLogicFeatures

@@ +1 @@
+{{{
+#!rst
+
+Control Logic Operation and Features of ianBMS
+===============================================
+
+Lighting control
+----------------
+
+Lights are controlled using bistable (ratchet) relays. A bistable relay is energized to change state 
+from open to closed and vice versa. Once its state changes the relay remains in the new state until
+it receives the next energization stimulus. One bistable is used for every lighting load (one or 
+more fixtures). The bistables are controlled by the RSC.
+
+Push-buttons are installed to allow the occupants manually toggle the lighting loads (typically 
+one button per load, but more in some spaces like hallways). The push-buttons are connected to controller 
+digital inputs therefore their association to lighting loads can be modified by reconfiguring the controller 
+logic. The occupants can also control the lights though a simple web-based HMI, as well as see the current 
+condition of all the lights in the building.
+ 
+Apart from manual lights control, the system also provides auto switch-off functionality during 
+after-hours. Auto switch-off will be activated when all three conditions are met:
+
+- It is after 20:00 in the evening and before 08:00 in the morning, or it is a non-working day
+- The illuminated space is not occupied, and has remained unoccupied for at least 15 minutes
+- The pushbuttons controlling the load have not been pressed for at least 15 minutes
+- No HMI command has been issued to turn-on the loads for at least 15 minutes
+
+If no motion sensor is installed in a room, or if a motion sensor is removed or stops to function 
+the system considers the room "always occupied" and acts accordingly.
+
+For some rooms (e.g. rarely visited storage rooms), auto switch-off functionality is enabled during
+working hours as well. For these rooms, if no motion sensor is present to determine occupancy the lights 
+are switched-off after 15 minutes regardless of occupant presence. 
+
+For the restrooms the auto switch-off functionality is also enabled during working hours. The switch-off 
+delay is set to 30minutes (instead of 15).
+
+A global "leave the building" push-button is also provided which, when pressed, switches off 
+all the lights with the exception of the ones illuminating the exit hallway; these are turned on and 
+remain on for 2 minutes permitting the occupant to leave the building.
+
+If controller fails to change the state of a load (fails turn off or on a light), then after 
+10 retries it declares the bistable relay malfunctioning and raises the respective failure alarm.
+
+
+Air conditioning
+----------------
+
+Ceiling mounted fan-coil units are used for air-conditioning the office space. They can operate in three 
+fan speeds (low, medium, high). The temperature in each room will be measured by the controller (using temperature sensors)
+and the fan-coils will be switched on and off as well as between speeds in order to achieve a 
+set-point. Through the web HMI the occupant will be able to control:
+
+- The speed of the fans. Four options will be given: off, low, med, high, auto.
+- The set-point temperature. The occupant will be able to configure the setpoint temperature between 
+  18 and 28 degrees celcius
+
+Regardless of the set-point and fan-speed configured by the occupant, the system will fall-back to 
+a special "unocupied" operating mode when all the following conditions are met:
+
+- It is after 20:00 in the evening and before 08:00 in the morning, or it is a non-working day
+- The room is not occupied, and has remained unoccupied for at least 10 minutes
+
+In unoccupied mode a predefined (non occupant-configurable) set-point will be used.
+With this setpoint---which will be rather low durring heating season, and rather high during 
+cooling season---energy will be conserved when the building is unmanned. Through the web-HMI the occupant 
+will be able to set the room back to normal air-conditioning mode even durring after hours. Once the room 
+is manually set to normal mode, it will remain so for at least 1 hour, then it will switch-back to 
+unoccupied mode provided that the conditions above are still satisfied (i.e. that it is still before 08:00, 
+and the room is still unoccupied).
+
+At 08:00 in the morning the system will enter "boost" mode, whereby the fan-coil unit will operate at full
+capacity until the occupant-configurable setpoint is reached. Boost-mode helps bring the office-space back 
+to normal temperature quickly.
+
+To better understand the operation of the system consider the following example scenario:
+
+The user has set the fan-speed to "auto", and the setpoint to 22 degC. The administrator has set the 
+unoccupied-mode setpoint to 16 degC. The occupant leaves the room at 19:00, at which point the temperature has 
+been stabilized at the setpoint (22 degC). The room will be kept at this temperature until 20:00 at which
+time---given that the room is unoccupied and has remained so for more than 10 minutes---the system will 
+set the room to "unoccupied" mode. The fan-coil will be switched-off for the night and will be turned on 
+only if the temperature drops below 16 degC. At 23:00 the occupant enters the room, and using the web 
+HMI sets the air conditioning system back to normal mode. 
+The fan-coil starts operating in order to bring the room temperature back 
+to the setpoint (to 22 degC). The room will remain at "normal" mode for at least 1-hour, even if 
+the occupant departs earlier. While this not the most efficient setting, it limits the reliance on the 
+occupancy sensor and reduces the amount of inconvinience in case of a sensor failure: That is, if the sensor 
+is not working, and the occupant wishes to remain in the building after-hours he has to re-set the
+system to "normal" mode once every hour. Of course if the sensor is working properly the system will remain 
+in "normal" mode, as long as the occupant is present.
+
+In order to protect the electrical installation from transient over loading, air-conditioning loads 
+will be actuated using "delayed loading" logic than will guarantee a minimum spacing 
+of 5 seconds between to consecutive load activations. This will be especially useful when boost mode is 
+activated in the morning  
+
+
+Server room free cooling
+------------------------
+
+The server room will be cooled by two systems: A split-unit air conditioner, and a free-cooling air exchange
+system. The air-conditioner will operate autonomously using a constant set-point. The free-cooling system
+will operate under the control of the RSC. The controller will measure the internal and external temperature
+and humidity and calculate the respective enthalpy values. If the external enthalpy is lower than the internal enthalpy and the external humidity is lower than a given level, air from outside will be fed to the room by
+activating the fan of the free-cooling system. Using free cooling the room temperature will be allowed to drop
+considerably below the air-conditioning set-point, respecting only a failsafe limit. Bringing the server 
+room temperature below the setpoint, will force the air-conditioning system to turn its compressor off, 
+thus conserving energy. The energy consumption of (the current drawn by) both the split unit air-conditioner, 
+as well as the free cooling system will be measured by the controller and logged in order to permit an 
+estimation of the efficiency of the system. The temperature and humidity inside the server room will also 
+be monitored, and logged every 5 minutes. Logs---for temperature and energy consumption---will be held in 
+the controller's memory for one week. Alarms will be generated for high temperature and high humidity inside 
+the server room
+
+Occupancy monitoring
+--------------------
+
+Consumption measurement
+-----------------------
+
+Other alarms
+------------
+
+Web HMI main screen
+-------------------
+
+- Current room temperature (read only)
+- Normal mode temperature-setpoint (configurable)
+- Unoccupied mode temperature setpoint (read only)
+- Air conditioning unit fan-speed setting (configurable)
+- Air conditioning unit actual fan-speed (read only)
+- Lights status, and "activate" / "deactivate" commands
+- Current occupancy indication
+- External temperature
+- External humidity
+
+- Smoke detection alarm for server room, kitchen, hardware room, and hallways 
+  (3 indications)
+- Leak detection alarm for restrooms and kitchen
+
+}}}