CCMR20 Time Delay Fuse

CCMR20 Time Delay Fuse

CCMR20 Time Delay Fuse – Industrial Dual-Element Class CC Power Fuse

The CCMR20 Time Delay Fuse (part of the Littelfuse POWR-PRO® CCMR series) is an industrial-grade, dual-element rejection fuse designed to provide motor branch-circuit and short-circuit protection. Engineered for space-saving panel installations, the CCMR20 Time Delay Fuse safely accommodates sustained starting currents and temporary voltage surges without nuisance tripping.

As seen in the product image, the fuse utilizes a cylindrical melamine body with rejection-style ferrule caps. Designed with dual-element construction, it offers Type 2 “No Damage” protection for both NEMA and IEC motor starters, control circuits, and automated machinery.

Key Features of the CCMR20 Time Delay Fuse

• Dual-Element Time-Delay Design: Safely absorbs temporary current inrush—such as motor starting spikes or transformer energization—preventing unnecessary downtime.

• Extreme Current Limitation: Rapidly isolates severe fault conditions in fractions of a cycle, shielding sensitive downstream components from thermal and magnetic stress.

• High Interrupting Capacity: Rated for 200,000 A RMS symmetrical interrupting rating at 600 VAC, ensuring safe fault clearing on high-fault current supply lines.

• Compact Class CC Form Factor: Delivers $600text{ V}$ protection within a standard 13/32″ x 1-1/2″ body size, reducing control panel footprint compared to traditional Class R fuses.

• Class CC Rejection Feature: Built with a rejection grooved end cap to prevent accidental substitution with lower-rated supplemental fuses.

• Global Agency Compliances: Meets strict safety guidelines, including UL 248-4 (Class CC), CSA Certified, CE, and RoHS standards.

Common Applications and Industrial Usage

The current-limiting and time-delay characteristics of the CCMR20 Time Delay Fuse make it a preferred protective component across commercial and industrial control setups:

• Motor Branch-Circuit Protection: Protects small fractional-to-medium horsepower motors (up to $40text{ HP}$ across the series) against short-circuits and overload conditions.

• HVAC Compressors & Fan Drives: Installed in rooftop air conditioners, chillers, and commercial refrigeration units requiring sustained motor-start capability.

• Control Power Transformers: Protects primary circuits of power distribution transformers against line-side faults and magnetizing inrush spikes.

• Industrial Control Panels (UL 508A): Serves as main branch protection inside space-constrained industrial automation enclosures, motor control centers (MCCs), and pump panels.

Technical Specifications

The electrical ratings, physical dimensions, and operational characteristics of the CCMR20 Time Delay Fuse conform to standard UL Class CC parameters:

Installation Guidelines and Best Practices

Safety Precaution: Always disconnect main power and test with a calibrated multimeter to confirm zero voltage before removing or replacing branch fuses.

• Fuse Block Compatibility: Install only in UL-approved Class CC rejection-style fuse blocks or DIN-rail finger-safe fuse holders (such as the Littelfuse LPSC series).

• Sizing Guidelines: Size the fuse according to NEC Article 430 requirements for motor branch short-circuit protection, typically sizing between 150% and 250% of full-load amps (FLA).

• Maintaining 3-Phase Balance: When a blown fuse is detected in a three-phase motor system, inspect all three fuses to ensure no thermal damage occurred on adjacent phases.

To review official Class CC fuse time-current characteristic curves, peak let-through energy tables, and complete POWR-PRO circuit protection guides, check the global Littelfuse Electrical Protection Directory.

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