FLM 20A Midget Fuse

FLM 20A Midget Fuse – Time-Delay Supplemental Power Cartridge Fuse

The FLM 20A Midget Fuse (part of the Littelfuse POWR-GARD® FLM series, part number FLM020 / 0FLM020.T) is an industrial-grade, time-delay supplemental fuse. Engineered to provide overcurrent and short-circuit protection, the FLM 20A Midget Fuse absorbs temporary inrush surges without nuisance tripping.

As depicted in the product image, the fuse features a cylindrical cartridge body fitted with nickel-plated end caps. Designed in the industry-standard $10 times 38text{ mm}$ ( $13/32text{"} times 1text{-}1/2text{"}$ ) Midget form factor, it provides supplementary protection for control transformers, solenoids, small motors, and industrial control circuits.

Key Features of the FLM 20A Midget Fuse

Time-Delay (Slo-Blo) Performance: Carries initial current surges—such as motor startup spikes or transformer energization—without premature blowing.
High Interrupting Capacity: Rated for a $10,000text{ A}$ interrupting rating at $250text{ VAC}$ and $125text{ VDC}$ , isolating short circuits safely.
Standardized 5AG Midget Size: Fits standard $10 times 38text{ mm}$ ( $13/32text{"} times 1text{-}1/2text{"}$ ) fuse blocks, finger-safe DIN-rail holders, and panel-mount clips.
Cost-Effective Design: Constructed with a high-durability fiber/paper casing and nickel-plated bronze ferrule end caps for consistent electrical conductivity.
Dual AC/DC Voltage Capabilities: Operates across systems rated up to $250text{ VAC}$ or $125text{ VDC}$ .
Global Agency Standards: Meets strict safety guidelines, including UL Listed 248-14, CSA Certified, CE marked, and RoHS compliant.

Common Applications and Industrial Usage

The time-lag response and supplementary design of the FLM 20A Midget Fuse make it a protective component across various equipment:

Control Circuit Transformers: Protects primary and secondary transformer windings from sustained overloads while tolerating high magnetizing inrush currents.
Solenoids & Relays: Shields inductive actuators, electromagnetic coils, and relay circuits against current spikes.
Small Fractional Motor Protection: Serves as supplemental protection for small single-phase and three-phase motors prone to high starting currents.
Power Supplies & HVAC Controls: Integrated into industrial automation panels, street lighting systems, UPS units, and commercial HVAC controllers.

Technical Specifications

The electrical, thermal, and mechanical parameters of the FLM 20A Midget Fuse conform to standard UL 248-14 supplemental specifications:

Parameter Specification	Technical Details & Operational Values
Component Classification	Supplemental Time-Delay Midget Fuse
Primary Target Keyword	FLM 20A Midget Fuse
Manufacturer Part Number	`FLM020` / `0FLM020.T`
Amperage Rating	$20text{ A}$
Voltage Ratings	$250text{ VAC} / 125text{ VDC}$
Interrupting Rating (AIR)	$10,000text{ A}$ @ $250text{ VAC}$ / $10,000text{ A}$ @ $125text{ VDC}$
Time-Delay Response Time	Minimum $12text{ seconds}$ @ $200%$ rated current
Body Dimensions	Diameter: $10.3text{ mm}$ ( $13/32text{"}$ x Length: $38.1text{ mm}$ ( $1text{-}1/2text{"}$ )
Body Material / Caps	Fiber/Paper Casing with Nickel-Plated Bronze End Caps
Terminal / Mounting Style	Ferrule / Cartridge Mount (Clip / Block)
Equivalent Cross-References	Bussmann `FNM-20`, Mersen `TRM20`

Installation Guidelines and Best Practices

Safety Precaution: Disconnect main power sources before inspecting or replacing cartridge fuses in panel holders.

Distinguish Branch vs. Supplemental Protection: Use the FLM 20A Midget Fuse for supplemental circuit protection. For main motor branch-circuit protection requiring rejection features, use Class CC fuses (such as KLDR or CCMR series).

Holder Compatibility: Install only in appropriate $10 times 38text{ mm}$ fuse holders, such as the Littelfuse L60030M fuse block or LPSM finger-safe series.

Visual Inspection: Because the FLM series is non-indicating, check blown fuses with a digital multimeter (continuity mode) or pair with an indicating fuse block.

To review official midget fuse time-current characteristic curves, interrupting ratings, and complete supplemental circuit protection guides, check the global Littelfuse Electrical Protection Directory.

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