Equivalent & Substitute Parts for RI-27AA Glass Body Reed Switch

Part Overview

The RI-27AA is a Glass Body Reed Switch manufactured by Comus International, classified as SPST-NO (Single Pole Single Throw Normally Open) with a 500mA switching capacity at 140V AC. This component is designated as Obsolete, necessitating identification of equivalent substitute parts for continued system design and procurement. The RI-27AA operates within a 16–25AT (Ampere-Turn) range and is suitable for applications requiring 10W power handling with rapid switching characteristics (0.25ms operate time, 0.03ms release time).

Substiute Parts

RI-27AA

Comus InternationalIn Stock: 1044RI-27AA Datasheet

Current PartRFQ

RI-27GP1520

Comus InternationalIn Stock: 894RI-27GP1520 Datasheet

SimilarRFQ

MDSR-7-10-20

Littelfuse Inc.In Stock: 44222MDSR-7-10-20 Datasheet

DirectRFQ

MDSR-10-10-15

LittelfuseIn Stock: 4017MDSR-10-10-15 Datasheet

SimilarRFQ

MDSR-10-15-20

Littelfuse Inc.In Stock: 4201MDSR-10-15-20 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution for the RI-27AA is determined by electrical equivalence across the following critical parameters: circuit type (SPST-NO), switching voltage ratings (140V AC / 200V DC minimum), rated power (10W), and switching current capacity (500mA minimum). Mechanical compatibility is ensured through matching mounting type (Through Hole) and termination style (Axial).

Four substitute parts satisfy these requirements with varying degrees of parameter alignment:

Primary Substitute (Same Series, Comus International): RI-27GP1520 maintains the identical manufacturer lineage, voltage/power ratings, and switching current capacity while offering an operating range of 15–20AT and Active product status.

Alternative Substitutes (Littelfuse Inc.): MDSR-7-10-20, MDSR-10-10-15, and MDSR-10-15-20 provide functional equivalence through matching SPST-NO circuit configuration, 140V AC / 200V DC switching voltages, 10W power rating, and 500mA DC switching capacity. These parts vary in operate range specification and are all Active with current inventory availability.

Parameter Comparison

Engineering Selection Recommendations

RI-27GP1520 is the preferred substitute, offering identical voltage and power specifications with Active product status. This part maintains manufacturer continuity within the Comus International RI-27 series and is currently in stock with 784 units available. ROHS3 compliance certification supports continued design acceptance in modern supply chains.

The three Littelfuse alternatives (MDSR series) provide functional equivalence for DC switching applications where 500mA capacity is required at 140V/200V ratings. All three Littelfuse parts carry Active product status with substantial inventory depth (3,997–44,188 units). However, AC switching current is reduced to 350mA across these options, which may limit applicability in AC-dominant circuits. The wider operate range specification in MDSR-7-10-20 (10–20AT) provides the broadest magnetic activation envelope among Littelfuse options.

Operating temperature range extends to –55°C on RI-27GP1520 and RI-27AA, whereas Littelfuse alternatives operate from –40°C. This difference is significant only for cryogenic or severe low-temperature applications.

Frequently Asked Questions (FAQ)

Q: Can MDSR-7-10-20 directly replace RI-27AA in AC circuits? A: No. While MDSR-7-10-20 meets the 140V AC switching voltage rating and 10W power specification, its AC switching current is limited to 350mA compared to the RI-27AA's 500mA. Circuit design must account for the reduced AC current capacity.

Q: What is the key difference between RI-27GP1520 and RI-27AA? A: The operate range differs: RI-27GP1520 requires 15–20AT versus RI-27AA's 16–25AT. Both parts carry identical switching current, voltage, and power ratings. RI-27GP1520 is Active while RI-27AA is Obsolete.

Q: Are all substitute parts Through Hole mounted with Axial termination? A: Yes. All four substitute parts (RI-27GP1520, MDSR-7-10-20, MDSR-10-10-15, MDSR-10-15-20) share identical Through Hole mounting and Axial termination geometry compatible with the original RI-27AA footprint.

Q: How does switching speed differ between the main part and substitutes? A: RI-27AA operates with 0.25ms engage and 0.03ms release timing. Littelfuse alternatives exhibit slower switching: MDSR-7-10-20 operates at 0.6ms/0.2ms, while MDSR-10-10-15 and MDSR-10-15-20 operate at 0.5ms/0.1ms. RI-27GP1520 matches the original timing specification. Time-critical applications must account for these differences.

Q: Which substitute supports the widest magnetic operate range? A: MDSR-7-10-20 provides the broadest operate range at 10–20AT, offering flexibility in applications with varying magnetic field conditions.

Q: What is the current inventory status of each part? A: RI-27AA (Obsolete): 963 units. RI-27GP1520 (Active): 784 units. MDSR-7-10-20 (Active): 44,188 units. MDSR-10-10-15 (Active): 3,997 units. MDSR-10-15-20 (Active): 4,170 units.