25SST120 Equivalent & Substitute Parts Reference

Part Overview

The 25SST120 is a solid-state relay (SSR) manufactured by Sensata-Crydom, configured as a SPST-NO (1 Form A) device in a hockey puck package. This component is designed for AC load switching applications with a 25A capacity at 90-140V load voltage. The 25SST120 is classified as obsolete, making identification of suitable substitute components necessary for ongoing system maintenance and new design implementations.

Substiute Parts

25SST120

Sensata-CrydomIn Stock: 102325SST120 Datasheet

Current PartRFQ

MCST1225CS

Sensata-CrydomIn Stock: 763MCST1225CS Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 25SST120 is determined by the following critical parameters:

• Circuit Configuration: Must remain SPST-NO (1 Form A) to maintain identical switching topology
• Load Current Rating: Must support minimum 25 A continuous operation
• Load Voltage Range: Must accommodate 90 V – 140 V AC operation
• Output Type: Must support AC switching; proportional control capability is permissible as an enhancement
• Package / Case: Must be hockey puck form factor to ensure mechanical compatibility with existing mounting infrastructure
• Mounting Type: Must be chassis mount to maintain installation compatibility
• Input Voltage Compatibility: Substitute input voltage range must encompass or exceed the original 4.6 – 10 VDC specification

The MCST1225CS meets all mandatory substitution criteria while offering enhanced input voltage flexibility and active product status.

Parameter Comparison

Engineering Selection Recommendations

The MCST1225CS is the primary substitute for the 25SST120 based on the following engineering criteria:

Functional Equivalence: Both components maintain identical SPST-NO circuit topology, 25 A load current capacity, and 90-140 V AC load voltage range. The MCST1225CS proportional control capability is a functional enhancement that does not compromise direct substitution.

Product Status: The MCST1225CS holds active product status with ongoing manufacturer support, whereas the 25SST120 is obsolete. This transition ensures long-term component availability and supply chain continuity.

Compliance: The MCST1225CS is RoHS compliant, meeting current environmental and regulatory standards. Both components share identical ECCN and HTSUS classifications.

Input Voltage Advantage: The MCST1225CS input voltage range (0 – 10 VDC) extends below the original specification (4.6 – 10 VDC), providing broader control signal compatibility without compromising the original operating window.

Termination Consideration: The MCST1225CS uses screw terminal termination versus the original quick connect style. This represents a mechanical interface change requiring connector adaptation during installation.

Frequently Asked Questions (FAQ)

Q: Can the MCST1225CS directly replace the 25SST120 without circuit modification?

A: The MCST1225CS maintains electrical equivalence across all critical parameters: circuit topology, load current, load voltage range, and input voltage compatibility. However, the termination style differs (screw terminal versus quick connect), requiring mechanical adapter or terminal reconfiguration.

Q: What is the significance of the MCST1225CS proportional control capability?

A: Proportional control is an additional feature that does not alter the component's ability to function as a standard SPST-NO relay. Existing circuits using on/off control will operate identically; the proportional capability remains unused unless explicitly implemented in the control circuit.

Q: Does the extended input voltage range (0 – 10 VDC) of the MCST1225CS affect compatibility?

A: No. The original 4.6 – 10 VDC specification is fully contained within the MCST1225CS range of 0 – 10 VDC. All control signals within the original operating window will function identically on the substitute component.

Q: Are there mechanical compatibility concerns with the hockey puck package?

A: Both components use identical hockey puck form factors and chassis mount configurations. Mechanical mounting compatibility is maintained. The termination style change (quick connect to screw terminal) is the only interface modification required.

Q: What is the inventory status for the MCST1225CS?

A: The MCST1225CS is available with 666 pieces in stock as new original inventory, ensuring immediate procurement availability for replacement and new design applications.