Fire Detection Isolation Circuit Impedance Fault Analysis
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Solution Overview
Problem
Fire detection and alarm systems with isolation circuits are susceptible to false positives due to electrostatic discharge, lightning strikes, or transient signals, as they rely solely on voltage or current monitoring, failing to accurately distinguish between actual and false short circuits.
Innovation Solution
An isolation circuit that uses a combination of current and voltage data to determine impedance and control isolation switches, allowing for precise zone isolation based on merged data rather than individual parameters, thereby distinguishing between actual and false short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If isolation circuits are used to reduce wiring and labor costs, then installation cost and system size are reduced, but the system becomes susceptible to false positives from electrostatic discharge, lightning strikes, or transient signals
Solution Approach 1:
The patent combines voltage monitoring and current monitoring into a unified isolation control system. By merging these two monitoring functions and requiring both to indicate a true short circuit condition before triggering isolation, the system maintains the benefits of isolation circuits while eliminating false positives caused by transient voltage or current spikes alone.
Solution Approach 2:
The patent changes the decision parameter from single-parameter monitoring (voltage or current alone) to dual-parameter monitoring (both voltage and current). This parameter change allows the system to distinguish between transient disturbances (which typically affect only one parameter) and true short circuit conditions (which affect both parameters simultaneously), thereby reducing false positives while maintaining installation efficiency.
2Ease of operation
If voltage or current monitoring alone is used to detect short circuits, then the system is simpler to operate, but it cannot accurately distinguish between actual and false short circuits
Solution Approach 1:
The patent merges voltage monitoring and current monitoring functions into a single detection system. The controller receives both voltage signals and current signals, and only triggers isolation when both indicate a short circuit condition, thereby improving detection accuracy while maintaining operational simplicity through automated dual-parameter evaluation.
Solution Approach 2:
The system implements feedback by continuously monitoring both voltage and current levels and using this information to dynamically control the isolation switch. The controller evaluates both parameters and adjusts the isolation state accordingly, providing accurate distinction between true and false short circuits while keeping the system easy to operate through automatic decision-making.
Data Source
AI summary
In an aspect, a fire detection system is described. The first detection system may include isolation circuit having an isolation switch coupled with a system line of the fire detection system and configured to isolate a first side of the system line from a second side of the system line. The isolation circuit may also include a controller coupled with the isolation switch. The controller may be configured to detect a short circuit on the system line and control the isolation switch based on a calculated impedance on the system line in response to detecting the short circuit.