<h2>Overview</h2>
<p>The <strong>Bussmann Fusetron FRN-R-2¼</strong> is a UL-listed Class RK5 dual-element, time-delay fuse designed for industrial and commercial circuit protection. This lot includes 7 individual units rated 2.25A at 250Vac or 125Vdc. The time-delay design allows temporary motor inrush currents to pass safely while protecting against sustained overloads and short circuits.</p>
<h2>Key Features</h2>
<ul>
<li><strong>Dual-Element Construction:</strong> Separate overload and short-circuit elements for coordinated protection</li>
<li><strong>Time-Delay Response:</strong> 8-second minimum delay at 500% of rated current, allowing motor startup surges without nuisance trips</li>
<li><strong>Current-Limiting:</strong> Opens in as little as 0.004 second during short-circuit conditions, minimizing fault damage</li>
<li><strong>Class RK5 Rating:</strong> UL Standard 248-12 compliance with 200kA RMS symmetrical interrupting rating (250Vac) and 20kA DC rating</li>
<li><strong>Non-Indicating Design:</strong> Standard ferrule-end cylindrical cartridge form factor for Class R rejection-type fuse blocks</li>
<li><strong>Lot of 7:</strong> Complete package for maintenance stock or multi-circuit replacements</li>
</ul>
<h2>Technical Specifications</h2>
<ul>
<li><strong>Amperage Rating:</strong> 2.25A (2¼A)</li>
<li><strong>Voltage (AC):</strong> 250Vac</li>
<li><strong>Voltage (DC):</strong> 125Vdc</li>
<li><strong>Interrupting Rating:</strong> 200kA RMS Sym @ 250Vac; 20kA @ 125Vdc</li>
<li><strong>Time-Delay Response:</strong> 8 seconds (minimum) at 500% rated current</li>
<li><strong>Short-Circuit Response:</strong> 0.004 second (dual-element)</li>
<li><strong>Body Material:</strong> Fiberglass tube with brass ferrules</li>
<li><strong>Physical Dimensions:</strong> 2 inches length × 9/16 inch diameter (nominal)</li>
<li><strong>Certification:</strong> UL Listed (File E4273, Standard 248-12); CSA Certified (C22.2 No. 248.12)</li>
<li><strong>Series:</strong> Fusetron FRN-R Class RK5</li>
</ul>
<h2>Typical Applications</h2>
<p>Class RK5 dual-element time-delay fuses like the FRN-R-2¼ are ideal for:</p>
<ul>
<li>Motor branch circuit protection with sized-to-overload coordination (as close as 125% motor FLA)</li>
<li>Equipment circuits requiring short-circuit and overload protection with nuisance-trip immunity</li>
<li>Industrial control panels and machine tool electrical systems</li>
<li>Pump motor and compressor circuits subject to temporary surge currents</li>
<li>Selective coordination in cascaded or multi-level protection schemes</li>
</ul>
<h2>Compatibility & Replacements</h2>
<h3>Compatible With</h3>
<ul>
<li>Class R rejection-type fuse blocks and holders</li>
<li>Industrial control systems and motor starters operating at 250Vac or 125Vdc</li>
<li>Equipment using UL Standard 248-12 Class RK5 fuse slots</li>
<li>Electrical panels with selective-coordination protection requirements</li>
</ul>
<h3>Replaces / Drop-In Replacement For</h3>
<ul>
<li>Previous Bussmann FRN-R-2¼ and FRN-R-2.25A units</li>
<li>Equivalent Littelfuse FLNR-2¼ and FLNR-2.25 (Class RK5)</li>
<li>Mersen TR-R series 2.25A time-delay Class R fuses</li>
<li>Edison ECNR-2¼ / ECNR-2.25 dual-element fuses</li>
</ul>
<h3>Works With</h3>
<ul>
<li>All UL-compliant Class R rejection-type fuse holder designs</li>
<li>Eaton/Bussmann fuse blocks and panel-mount carriers</li>
<li>IEC-compliant industrial control equipment operating at 250V or 125V DC</li>
<li>Any circuit requiring ANSI/UL Standard 248-12 Class RK5 rated protection</li>
</ul>
