Initial Technical Brief v0.2
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- **Filename:** industrial-cooling-initial-technical-brief.md
- **File Type:** md
- **Path:** docs/client/industrial-cooling-initial-technical-brief.md

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Source client technical brief used for requirements derivation

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.. raw:: html

   <h1>Industrial Cooling Systems S.L.</h1>
   <h2>Cabinet Cooling Protection Unit</h2>
   <h3>Initial Technical Brief</h3>
   <p><strong>Version:</strong> 0.2</p>
   <p><strong>Document Type:</strong> Pre-Requirements Technical Brief</p>
   <hr/>
   <h1>1. Product Overview</h1>
   <p>Industrial Cooling Systems S.L. is developing a compact cooling protection unit intended for installation inside industrial electrical cabinets.</p>
   <p>The unit is responsible for:</p>
   <ul>
   <li>Monitoring cabinet environmental conditions</li>
   <li>Controlling a cooling fan</li>
   <li>Protecting cabinet electronics from overheating</li>
   <li>Signaling abnormal operating conditions</li>
   </ul>
   <p>The product will operate continuously in industrial environments and must prioritize reliability and protective behavior.</p>
   <hr/>
   <h1>2. Intended Operation</h1>
   <p>The system shall:</p>
   <ul>
   <li>Continuously monitor internal cabinet temperature</li>
   <li>Monitor cooling fan rotational speed (RPM feedback)</li>
   <li>Monitor supply voltage</li>
   <li>Control fan activation</li>
   <li>Provide alarm signaling under abnormal conditions</li>
   </ul>
   <p>The device must prioritize equipment protection over continued operation.</p>
   <p>In unsafe conditions, protective behavior must override normal cooling logic.</p>
   <hr/>
   <h1>3. Safety Expectations (Fixed Thresholds)</h1>
   <p>The following safety limits are fixed and shall not be configurable.</p>
   <h2>3.1 Critical Overtemperature</h2>
   <p>If internal temperature exceeds <strong>85°C</strong>, the system must:</p>
   <ul>
   <li>Disable active outputs</li>
   <li>Activate alarm signaling</li>
   <li>Enter protective behavior</li>
   </ul>
   <h2>3.2 Voltage Protection</h2>
   <p>If supply voltage is:</p>
   <ul>
   <li>Below <strong>18V</strong>, or</li>
   <li>Above <strong>30V</strong>,</li>
   </ul>
   <p>The system must enter protective behavior.</p>
   <h2>3.3 Fan Failure Detection</h2>
   <p>If the cooling fan is commanded ON and no valid RPM feedback is detected within a defined timeout period, the system must treat this as a fault.</p>
   <p>The timeout value may be configurable within defined limits.</p>
   <hr/>
   <h1>4. Configurable Parameters</h1>
   <p>The following parameters shall be configurable:</p>
   <ul>
   <li>Fan activation temperature (default 60°C)</li>
   <li>Fan deactivation temperature (default 50°C)</li>
   <li>Warning temperature threshold (default 70°C)</li>
   <li>Fan failure detection timeout (default 5 seconds)</li>
   </ul>
   <p>Configuration values must:</p>
   <ul>
   <li>Be validated before use</li>
   <li>Stay within predefined safe ranges</li>
   <li>Never override fixed safety limits</li>
   </ul>
   <hr/>
   <h1>5. Diagnostics &amp; Logging</h1>
   <p>The device shall:</p>
   <ul>
   <li>Store the last detected fault condition</li>
   <li>Provide structured fault identifiers</li>
   <li>Maintain firmware version information</li>
   <li>Allow inspection of current operating status</li>
   </ul>
   <p>Persistent fault memory is desirable but not mandatory in the initial version.</p>
   <hr/>
   <h1>6. Reliability Expectations</h1>
   <p>The firmware must:</p>
   <ul>
   <li>Operate deterministically</li>
   <li>Avoid undefined behavior</li>
   <li>Handle invalid sensor readings gracefully</li>
   <li>Prevent unstable output oscillations</li>
   <li>Recover safely from transient conditions</li>
   </ul>
   <hr/>
   <h1>7. Interfaces</h1>
   <h2>7.1 Communication Interface</h2>
   <p>The device shall provide an industrial communication interface for:</p>
   <ul>
   <li>Reading current measurements</li>
   <li>Reading current status</li>
   <li>Reading last fault information</li>
   <li>Writing configuration parameters</li>
   </ul>
   <p>Preferred interface:</p>
   <ul>
   <li>RS-485 using Modbus RTU protocol</li>
   </ul>
   <h2>7.2 Local Indication</h2>
   <p>The device shall include:</p>
   <ul>
   <li>One RGB status LED</li>
   </ul>
   <p>The LED shall indicate:</p>
   <ul>
   <li>Normal operation</li>
   <li>Warning condition</li>
   <li>Fault or protective behavior</li>
   </ul>
   <p>Exact LED behavior (steady or blinking patterns) will be defined during firmware design.</p>