Littelfuse 0251015.NRT2 Equivalent & Substitute Parts

Part Overview

The Littelfuse 0251015.NRT2 is a 15 A, 32 V AC/DC board mount axial fuse in the PICO® II 251 series. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The fuse is designed for through-hole mounting applications requiring fast-blow response characteristics with a breaking capacity of 50 A AC and 300 A DC at rated voltage.

Key Parameters

Parameter	Value
Current Rating	15 A
Voltage Rating (AC)	32 V
Voltage Rating (DC)	32 V
Response Time	Fast Blow
Mounting Type	Through Hole
Package / Case	Axial
Breaking Capacity @ Rated Voltage	50 A AC, 300 A DC
Melting I²t	68.8
Operating Temperature Range	-55°C ~ 125°C
DC Cold Resistance	0.00446 Ohms
Size / Dimension	0.110" Dia x 0.280" L (2.80mm x 7.11mm)
Approval Agency	CSA, cURus

Substitute Part Grouping Explanation

Substitution for the obsolete 0251015.NRT2 is determined by strict equivalence across the following critical parameters:

Current Rating, Voltage Rating (AC and DC), Response Time, Mounting Type, Fuse Type, Breaking Capacity, Melting I²t, Approval Agency, Operating Temperature Range, DC Cold Resistance, and Size/Dimension.

Substitute parts are grouped into two categories:

Littelfuse PICO® II 251 Series (Parametric Equivalents): Parts 0251015.MXL, 0251015.HAT1L, 0251015.MRT1L, and 0251015.NRT1L maintain identical electrical and mechanical specifications. These parts differ only in packaging format (Bulk or Cut Tape) and product status (Active vs. Obsolete). All are manufactured by Littelfuse Inc. and carry ROHS3 compliance.

Cross-Manufacturer Direct Equivalent: Part 7010.7170.13 (SCHURTER Inc.) provides functional equivalence with identical current, voltage, and response characteristics. This part operates within the same temperature range and carries equivalent approvals (CSA, UR). Minor dimensional and melting I²t variations exist due to manufacturer design differences, but electrical performance remains equivalent for the specified application.

Parameter Comparison

Parameter	0251015.NRT2 (Main)	0251015.MXL	0251015.HAT1L	0251015.MRT1L	0251015.NRT1L	7010.7170.13
Manufacturer	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	SCHURTER Inc.
Current Rating (Amps)	15 A	15 A	15 A	15 A	15 A	15 A
Voltage Rating - AC	32 V	32 V	32 V	32 V	32 V	32 V
Voltage Rating - DC	32 V	32 V	32 V	32 V	32 V	32 V
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast Blow	Fast Blow	Fast Blow
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Fuse Type	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)
Breaking Capacity @ Rated Voltage	50 A AC, 300 A DC	50 A AC, 300 A DC	50 A AC, 300 A DC	50 A AC, 300 A DC	50 A AC, 300 A DC	300 A
Melting I²t	68.8	68.8	68.8	68.8	68.8	90
Operating Temperature Range	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 85°C
DC Cold Resistance	0.00446 Ohms	0.00446 Ohms	0.00446 Ohms	0.00446 Ohms	0.00446 Ohms	Not specified
Size / Dimension	0.110" Dia x 0.280" L (2.80mm x 7.11mm)	0.110" Dia x 0.280" L (2.80mm x 7.11mm)	0.110" Dia x 0.280" L (2.80mm x 7.11mm)	0.110" Dia x 0.280" L (2.80mm x 7.11mm)	0.110" Dia x 0.280" L (2.80mm x 7.11mm)	0.093" Dia x 0.315" L (2.36mm x 8.00mm)
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	CSA, cURus	CSA, cURus	CSA, cURus	CSA, cURus	CSA, cURus	CSA, UR

Engineering Selection Recommendations

For applications currently using the obsolete 0251015.NRT2, the following selection criteria apply:

Primary Recommendation - Littelfuse 0251015.NRT1L: This part provides exact electrical and mechanical equivalence with identical specifications across all critical parameters. Product status is Active, ensuring long-term availability. ROHS3 compliance and REACH Unaffected status support modern regulatory requirements. Packaging in Cut Tape (CT) format with 2,300 units in stock provides reliable procurement.

Alternative - Littelfuse 0251015.MXL: Identical specifications to 0251015.NRT1L with higher inventory availability (3,215 units). Bulk packaging format may be preferred for high-volume applications. ROHS3 compliant with REACH Unaffected status.

Secondary Options - Littelfuse 0251015.HAT1L and 0251015.MRT1L: Both maintain full electrical and mechanical equivalence. 0251015.MRT1L offers the highest inventory level (2,773 units). Both are ROHS3 compliant with REACH Unaffected status. Cut Tape packaging supports standard component handling.

Cross-Manufacturer Alternative - SCHURTER 7010.7170.13: Provides functional equivalence with identical current, voltage, and response characteristics. Operating temperature range is reduced to -55°C ~ 85°C compared to the Littelfuse series. Melting I²t is higher at 90 versus 68.8. Physical dimensions differ slightly (0.093" Dia x 0.315" L). This part is suitable only for applications where the reduced temperature range and dimensional variance are acceptable. CSA and UR approvals are equivalent to the main part's CSA and cURus certifications.

Frequently Asked Questions (FAQ)

Q: Can I directly replace 0251015.NRT2 with any of the Littelfuse substitute parts?

A: Yes. Parts 0251015.MXL, 0251015.HAT1L, 0251015.MRT1L, and 0251015.NRT1L are parametric equivalents with identical electrical and mechanical specifications. The primary difference is packaging format (Bulk or Cut Tape) and product status (Active vs. Obsolete). All are suitable for direct substitution.

Q: What is the difference between the packaging options?

A: Bulk packaging (0251015.MXL) is supplied in loose form, typically for high-volume manufacturing. Cut Tape (CT) packaging (0251015.HAT1L, 0251015.MRT1L, 0251015.NRT1L) provides components on continuous tape, suitable for automated assembly equipment. Electrical and mechanical performance is identical across all packaging formats.

Q: Can I use the SCHURTER 7010.7170.13 as a substitute?

A: The SCHURTER part provides functional equivalence for current, voltage, and response characteristics. However, it has a reduced operating temperature range (-55°C ~ 85°C versus -55°C ~ 125°C) and slightly different physical dimensions. Use this part only if your application does not require the full temperature range of the Littelfuse series and if the dimensional variance is compatible with your PCB layout.

Q: What does ROHS3 compliance mean for my application?

A: ROHS3 compliance indicates the part meets the Restriction of Hazardous Substances Directive, restricting the use of specific hazardous materials. All active substitute parts are ROHS3 compliant, supporting modern environmental and regulatory standards. The original 0251015.NRT2 is RoHS non-compliant, making the active substitutes preferable for new designs.

Q: Are there inventory considerations for selecting a substitute?

A: Yes. 0251015.NAT1L has the highest inventory (7,449 units), followed by 0251015.MXL (3,215 units) and 0251015.MRT1L (2,773 units). For applications requiring immediate procurement or high-volume orders, these parts offer superior availability. 0251015.NRT1L (2,300 units) and 0251015.HAT1L (752 units) have lower but adequate stock levels.

Q: What is the significance of the melting I²t value?

A: Melting I²t determines the thermal energy required to melt the fuse element and is critical for circuit protection timing. All Littelfuse substitutes maintain the identical melting I²t of 68.8, ensuring identical protection characteristics. The SCHURTER part has a higher melting I²t of 90, resulting in slightly slower response. This difference is acceptable only if your circuit protection requirements do not depend on the precise timing of the original part.

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