YOKOGAWA AIP591

Description

Product Overview: The YOKOGAWA AIP591 Electrical Isolator

The YOKOGAWA AIP591 is a single-channel, relay output type signal conditioner and isolator from Yokogawa’s renowned AIP (Advanced Industrial Platform) series. This device is engineered to provide precise electrical isolation, signal conversion, and transmission for critical process signals in industrial control and measurement systems. The primary role of the YOKOGAWA AIP591 is to accept a DC current or voltage input signal, condition it, and provide an electrically isolated relay contact output based on a user-configurable setpoint, effectively acting as a highly reliable and precise limit alarm or interlock device. It protects sensitive control equipment like PLC and DCS input cards from ground loops, high-voltage transients, and noise present in field wiring. For detailed technical data and manuals, always refer to the official YOKOGAWA AIP591 product page.

Product Parameters and Technical Specifications

• Input Signal: Accepts DC current (e.g., 4-20 mA) or voltage (e.g., 1-5V) signals. Specific ranges are selectable.

• Output: SPDT (Single-Pole, Double-Throw) relay contact output. Specifications include contact rating (e.g., 250V AC, 2A), material (e.g., gold-clad), and expected operational life.

• Isolation: Provides high-grade isolation (typically 1500V AC or higher) between input, output, and power supply circuits.

• Power Supply: Operates on a standard DC power supply, commonly 24V DC.

• Setpoint & Hysteresis: Features a user-configurable alarm setpoint and adjustable hysteresis to prevent relay chattering near the trip point.

• Accuracy & Response Time: High accuracy (e.g., ±0.1% of span) and fast response time for reliable alarm detection.

• Mounting: Designed for DIN-rail mounting, occupying a small footprint for high-density panel layouts.

Advantages and Key Features

• Unmatched Reliability & Precision: Yokogawa’s heritage in measurement and control ensures the AIP591 offers exceptional long-term stability and accuracy, which is critical for safety and process integrity.

• Robust Isolation: Superior noise immunity and protection against ground loops and surges, safeguarding expensive downstream control system components.

• Flexible Configuration: Simple setting via front-panel controls (DIP switches, potentiometers) allows for easy on-site configuration without complex software tools.

• High-Density Design: Slim form factor allows for efficient use of control panel space when multiple isolators are required.

• Proven Performance in Harsh Environments: Built to operate reliably in industrially challenging conditions with wide temperature ranges and high immunity to vibration and electrical noise.

Application Cases in Industry

• Process Alarm Trips in Petrochemical Plants: Isolating 4-20 mA signals from pressure, level, or temperature transmitters to trigger high/high-high or low/low-low alarms via relay to a safety system or PLC.

• Interlock Signaling in Power Generation: Converting a turbine speed or bearing vibration signal into a hardwired shutdown interlock to protect critical machinery.

• Signal Interface in Water Treatment: Accepting a chlorine residual analyzer’s output to activate a relay that starts/stop a chemical feed pump via a separate control circuit.

• Batch Process Control in Pharmaceuticals: Using the relay output from the AIP591 to signal the completion of a charge or a limit condition to the main batch controller.

• HVAC Building Management Systems: Providing isolated alarm contacts for critical duct pressure or chiller plant parameters.

Comparison with Competing Products
Compared to general-purpose signal isolators/relays from manufacturers like Phoenix Contact, Weidmüller, or Allen-Bradley, the YOKOGAWA AIP591 is distinguished by its focus on high-accuracy process control applications. While competitors offer excellent modularity and broad functional variety, the AIP591 excels in its specific niche of providing a highly reliable, precision-alarm function. It often features superior isolation specifications and Yokogawa’s renowned measurement-grade performance. Compared to a PLC’s own analog input and internal software alarm, the AIP591 provides a dedicated, physically isolated, and failsafe hardwired path, which is often required for safety-related or critical interlock functions.

Selection Suggestions and Precautions

• Selection Advice: Select the YOKOGAWA AIP591 when you need a highly reliable, standalone hardware alarm trip for critical process variables. It is ideal for applications requiring galvanic isolation for noise immunity or safety, and where a simple, configurable device is preferred over programming a software function block in a PLC. Confirm the input signal type, required relay contact rating, and setpoint adjustment method.

• Precautions:

  1. Carefully match the input signal range (e.g., 4-20mA vs. 0-10V) and the power supply voltage to your system specifications.

  2. Ensure the relay output’s contact rating (voltage and current) is suitable for the load it will be switching (e.g., a PLC digital input, a lamp, or a small contractor coil).

  3. Properly configure the hysteresis value to prevent excessive relay cycling if the process variable oscillates near the setpoint.

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