LA50QS504 Equivalent & Substitute Parts

Part Overview

The LA50QS504 is a 50A 500VAC/500VDC fast-blow cartridge fuse with bolt mount configuration, manufactured by Littelfuse Inc. under the POWR-GARD® LA50QS series. This component is classified as obsolete, with 686 units currently in stock. Due to its obsolete status, identifying equivalent substitute parts is essential for system maintenance, repair, and new design implementations where this fuse type is specified.

Substiute Parts

LA50QS504

Littelfuse Inc.In Stock: 758LA50QS504 Datasheet

Current PartRFQ

L50QS050.T

Littelfuse Inc.In Stock: 868L50QS050.T Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the LA50QS504 is determined by the following critical parameters:

• Current Rating: 50A (exact match required)
• Voltage Rating: 500 VAC and 500 VDC (exact match required)
• Fuse Type: Cartridge with fast-blow response (exact match required)
• Mounting Type: Bolt mount configuration (exact match required)
• Package / Case: Cylindrical with blade terminal (exact match required)

The substitute part L50QS050.T meets all mandatory electrical and mechanical parameters. While dimensional and performance characteristics differ, the core functional parameters align with the requirements for direct substitution in applications originally specified for the LA50QS504.

Parameter Comparison

Engineering Selection Recommendations

The L50QS050.T is the manufacturer-recommended substitute for the obsolete LA50QS504. Both components share identical electrical ratings (50A, 500VAC/VDC) and mechanical configuration (cartridge, bolt mount). The L50QS050.T carries active product status with expanded regulatory compliance including CE and cURus certifications in addition to UR approval. The substitute part meets ROHS3 compliance requirements, whereas the original part is non-compliant. For new designs or system upgrades, the L50QS050.T is the appropriate selection. For legacy system maintenance where physical space constraints exist, dimensional differences must be evaluated against available mounting clearance.

Frequently Asked Questions (FAQ)

Q: Can the L50QS050.T directly replace the LA50QS504 in existing installations?

A: Yes, the L50QS050.T meets all mandatory electrical and mechanical parameters for direct substitution. Both components are 50A, 500VAC/500VDC fast-blow cartridge fuses with bolt mount configuration. Physical installation space must accommodate the L50QS050.T's larger length (3.625" versus 2.130").

Q: What are the key differences between these two parts?

A: The primary differences are product status (obsolete versus active), regulatory compliance (ROHS3 compliant versus non-compliant), and physical dimensions. The L50QS050.T is longer and includes expanded certifications (CE, cURus). Breaking capacity at rated DC voltage differs (50kA versus 100kA).

Q: Are there any compatibility concerns with the different approval agencies listed?

A: Both parts carry UR approval. The L50QS050.T includes additional CE and cURus certifications, providing broader regulatory acceptance. The original part's CSA approval is not replicated in the substitute, but UR approval is maintained.

Q: What should be considered when selecting between these parts for a new design?

A: The L50QS050.T is the appropriate choice for new designs due to its active product status and ROHS3 compliance. The LA50QS504 should not be specified for new applications as it is obsolete.

Q: How do the melting I²t values affect substitution?

A: The L50QS050.T has a melting I²t value of 211. This parameter is provided only for the substitute part and represents thermal energy dissipation characteristics. This value should be evaluated against circuit protection requirements in the specific application.