Independent of sprinkler operation decisions, the system manages shed cooling on peripheral output P2 using a sophisticated thermostat mode designed to protect electronic equipment and prevent the shed itself from becoming an ignition source. The shed cooling operates on gravity-fed water supply, meaning it doesn't consume from the pump-fed tank and can operate even when pump-based systems are restricted by water level.
When internal shed temperature exceeds 60 degrees Celsius, P2 activates continuously to provide maximum cooling. This threshold represents the point at which electronic equipment begins experiencing reduced reliability and potential permanent damage, and where the wooden shed structure's auto-ignition temperature becomes a concern.
Below 60 degrees but above 47 degrees Celsius, the system implements pulse-based cooling with escalation logic. The thermostat first requires "arming" by observing internal temperature fall below 45 degrees Celsius. This two-degree deadband prevents repeated pulse initiation during small oscillations around 47 degrees. Once armed, when internal temperature rises to or above 47 degrees, the system initiates a one-minute cooling pulse—P2 activates for exactly 60 seconds then returns to off state.
The system tracks the time between pulse starts. If a new pulse begins less than two minutes after the previous pulse started, the system concludes that ambient cooling from brief pulses is insufficient and latches into continuous cooling mode, remaining continuously on until either the operator intervenes or internal temperature falls below 45 degrees for long enough to re-arm the system. This escalation prevents excessive relay cycling (which would eventually damage the relay contacts) while ensuring adequate cooling during sustained high-temperature conditions.
The shed thermostat mode operates independently of water level constraints. Even when sprinkler operation is disabled due to dry cutoff or gel priority mode, shed cooling continues based solely on internal temperature. This recognizes that the gravity-fed cooling system uses a separate water source and that equipment protection should continue even when fire defence is compromised.
An additional layer of decision-making addresses the question of how to deliver water during intermittent sprinkler cycles—should the main pump cycle on and off (pump cycling mode), or should the pump run continuously with the recirculation valve cycling (recirculation mode)? The choice has significant implications for battery consumption and diesel engine wear.
<< Autonomous Fire Defence Algorithms cont | | Autonomous Fire Defence Algorithms cont >> |Table of Contents>