Description

Yokogawa SARM55W Relay Output Terminal Board

The Yokogawa SARM55W, also cataloged as the SARM55W relay output terminal board, operates as a dedicated hardware component for discrete contact actuation within Yokogawa FIO digital output interface systems. Configured for field device switching in CENTUM VP / CS 3000 architectures, the Yokogawa SARM55W (SARM55W Relay Output Terminal Board) provides direct electrical relay execution between DO modules and external load circuits.

Suffix Breakdown & Model Matrix

• SARM: Yokogawa standard relay output terminal assembly family for FIO systems
• 55W: 32-point wet contact relay output configuration with dual-line field power segmentation
• No additional suffix variants or functional sub-matrix definitions are specified in the provided documentation

Hardware Specifications

Parameter	Specification
ModelBrand	Yokogawa SARM55W
Origin	Japan
Weight	2.2 kg
Dimensions	W 482.6 mm x H 132.5 mm (3U)
OperatingTemp	0 to 50 degC
PowerConsumption	24 VDC, max 0.65 A (internal circuit)
Contact Points	32-point relay output
Max Load 250 VAC	0.6 A per point
Max Load 30 VDC	0.6 A per point
Max Load 125 VDC	0.1 A per point
Insulation Resistance	>= 10 MOhm (500 VDC)
Withstanding Voltage	2 kV field-to-case, 500 V power-to-case
Field Device Supply	Dual-line, per 16-point group

Process Control Interface Electrical Architecture

Yokogawa process I/O architectures implement channel-level separation and controlled electrical isolation between field switching elements and system backplane logic. The SARM55W relay terminal board supports discrete output decoupling through mechanical contact isolation, ensuring separation between 24 VDC control power domains and external load circuits.

In DCS integration environments, channel-to-channel electrical independence is maintained through relay segmentation, minimizing cross-conduction paths under mixed AC/DC switching conditions. The terminal architecture aligns with distributed I/O designs where field wiring density is concentrated at rack-level termination points, reducing cabinet-level wiring dispersion and improving signal routing determinism in DO execution paths.

Frequently Asked Questions

Q: Can the SARM55W support mixed AC and DC load switching on adjacent channels?
A: Yes. Each relay channel is electrically isolated; however, load grouping must respect per-point current limits and field wiring separation standards.

Q: Does the board require external suppression for inductive loads?
A: External flyback or surge suppression is required at the field device level for inductive loads to prevent contact wear and arcing.

Q: Is hot-swap supported for the terminal board during operation?
A: Hot-swap behavior depends on system configuration; field termination should be de-energized prior to board removal to avoid relay contact stress.

Field Installation Guidelines

• Maintain separation between AC and DC wiring harnesses on field terminal blocks
• Ensure torque specification compliance for M4 terminal screws to avoid contact resistance drift
• Use shielded cables for high-noise industrial environments and terminate shields at single-point ground only
• Verify insulation resistance before energizing field circuits (minimum 10 MOhm recommended threshold)
• Do not exceed per-point current limits to prevent relay contact degradation
• Confirm correct allocation of dual-line field power groups (16-point segmentation)

Specifications

• Brand: Yokogawa

Advantages

• High reliability in industrial environments
• Supports continuous operation
• Compatible with major PLC/DCS systems