Circuit Protection > Over-Current Protection
Betterfuse Over-Current Protection Fuses
Quick Overview
Betterfuse SMD fuses are small, surface mount devices designed to provide supplemental overcurrent protection for high-current circuits across various applications. Their general design ensures temperature stability and performance reliability.
Details
Betterfuse fuses offer supplemental overcurrent protection and are ideal for use in blade servers, routers, battery systems, power factor correction (PFC) in high-wattage power supplies, and power distribution units (PDUs).
Overcurrent occurs when the current in an electrical circuit surges or increases beyond the normal flow. This condition is primarily caused by short circuits and overloads. An overcurrent happens when the current exceeds the circuit’s normal load. During a short circuit, the current deviates from its regular path due to insulation breakdown or faulty connections, bypassing the load and taking the path of least resistance.
Possible causes of overcurrent include:
- Overload
- Incorrect design
- Short circuits
- Arc faults
- Ground faults
To manage overcurrent (both overload and fault conditions), standard fuses and circuit breakers are commonly used as overcurrent protection devices (OCPDs).
Fuses, fusible links (which break to prevent further damage from short circuits or overloads), and circuit breakers are essential for protecting against sustained current overloads. Fuses, which come in various types and sizes depending on their application, are one-time-use OCPDs. They react up to six times faster in fault situations compared to circuit breakers but need to be replaced after an overcurrent event.
In power systems for emergency backup or off-grid use, fuses provide a critical overcurrent protection tool. They serve as a safety link, often used alongside a breaker, to shut off the system if an overcurrent causes excessive heating in the batteries, cables, or wiring due to an overload or ground fault.
SMD Fuse Series
Series 041/0402
The 041/0402 Series provides surface mount overcurrent protection for applications where space is at a premium and resettable protection is desired.
Fast-Acting
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IR: 200mA~4A UR: DC: 32V/24V 
Series 061/0603
Fast-Acting(F)
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Rated Current : 250mA~5A Rated Voltage: DC:32V 
Series 063/0603
The 063/0603 series is an 0603 Time-Lag fuse best suited for applications include electronic devices and batteries.
Time-Lag (T)
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Rated Current : 1A~5A Rated Voltage: DC:32V 
Series 064/0603
Fast-Acting(F)
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Rated Current:250mA~5A Rated Voltage: DC:63V/32V 
Series 065/0603
Fast-Acting(F)
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Rated Current : 250mA~8A Rated Voltage: DC:32V 
Series 066/0603
Time-Lag(T)
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Rated Current :
250mA~8A Rated Voltage: DC:32V 
Series 121/1206
Fast-Acting(F)
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Rated Current : 250mA~30A Rated Voltage: DC:63V/32V/24V
AC:32V 
Series 122/1206
Time-Lag(T)
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Rated Current : 4.5A~40A Rated Voltage: DC: 72V/63V/48V/36V/32V 
Series 123/1206
Time-Lag(T)
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Rated Current : 1A~5A Rated Voltage: DC:63V/32V
AC:12V 
Series 124/1206
Fast-Acting(F)
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Rated Current : 250mA~1.5A Rated Voltage: AC:125V
DC:125V 
Series 125/1206
Fast-Acting(F)
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Rated Current : 250mA~40A Rated Voltage: 72V/63V/32V/24V 
Series 126/1206
Time-Lag(T)
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Rated Current : 630mA~50A Rated Voltage: DC:72V/63V/32V/24V
Series 127/1206
Fast-Acting(F)
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Rated Current:250mA~20A Rated Voltage: AC:125V
DC125V/72V 
Series 241/2410
Fast-Acting(F)
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Rated Current : 2A~15A Rated Voltage: AC:125V
DC:125V 
Series 243/2410
Fast-acting(F)
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Rated Current : 100mA~40A Rated Voltage: 86/100/125V DC,125/250V AC 
Series 244/2410
Time-Lag(T)
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Rated Current : 250mA~7A Rated Voltage: AC:250V/125V
DC:125V 
Series 245/2410
Time-Lag(T)
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Rated Current:250mA~7A Rated Voltage: AC: 125V
DC: 125V 
Series 246/2410
Time-Lag(T)
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Rated Current : 250mA~7A Rated Voltage :
350Vac 
Series 247/2410
Fast-Acting(F)
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Rated Current : 250mA~1.5A Rated Voltage: AC: 125V
DC: 125V 
Series 249/2410
Fast-Acting(F)
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Rated Current:20A~40A Rated Voltage: DC:72V/63V 
Series 254/2410
Time-lag(T)
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Rated Current:1A~12A Rated Voltage: 250VAC,125VDC 
Series 475/1140
SMD1140,Time-Lag(T)
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Rated Current : 20A~60A Rated Voltage: 125V/250Vac 
Series 476/1140
SMD1140,Time-Lag(T)
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Rated Current : 500mA~5A Rated Voltage: AC:125V/250V
DC: 125V/250V 
Series 477/1140
SMD1040,Time-Lag
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Rated Current:15A~60A Rated Voltage: AC: 125/250V
DC: 32/60/72V
Series 487/1140
SMD1240,Fast-Acting(F)
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Rated Current:60A~100A Rated Voltage: AC: 125V
DC: 72V/63V/32V 
Series 491//12.5×10
This high-current SMD fuse is a compact, square, surface mount device designed to provide supplemental overcurrent protection for high-current circuits in various applications. Offering full-fault-spectrum protection, SMD Power Fuses detect and interrupt faults of all sizes-large, medium, and small-even down to the minimum melting current.
Fast-acting(F)
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Rated Current : 60A~100A Rated Voltage: DC:75V/100V 
Series 492//12.5×10
With Betterfuse Series 492//12.5×10 Series Fuses, source-side devices may be set for faster operation than practical with other power fuses or circuit breakers, thereby providing better system protection without compromising coordination.
Fast-acting(F)
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Rated Current :60A~100A
Rated Voltage: DC:75V/100V
