Foxboro RC27-1840 Signal Conditioner

Technical Specifications:

• Input Signal: 4–20 mA DC (2-wire or 4-wire)
• Output Signal: 4–20 mA DC or 1–5 V DC (selectable)
• Isolation Voltage: 1500 V DC between input, output, and power
• Power Supply Voltage: 24 V DC (nominal), range 18–30 V DC
• Accuracy: ±0.1% of span (typical)
• Response Time: < 100 ms (typical)
• Operating Temperature: -20°C to +70°C (-4°F to +158°F)
• Storage Temperature: -40°C to +85°C (-40°F to +185°F)
• Humidity: 5% to 95% RH (non-condensing)

Functional Features:

• Signal Isolation: Full galvanic isolation between field side and system side
• Signal Linearization: Supports linear 4–20 mA input without additional linearization
• Noise Filtering: Built-in low-pass filter with 4 Hz cutoff frequency (configurable)
• Fault Detection: Open-circuit and short-circuit input detection with diagnostic LED indicators
• Loop Power: Provides 24 V DC loop power to 2-wire transmitters (up to 500 Ω load)

Material Composition:

• Housing: Flame-retardant ABS plastic (UL 94 V-0 rated)
• Terminal Blocks: Phosphor bronze with gold plating
• PCB: FR-4 epoxy glass with conformal coating
• Connectors: Standard Euro-style terminal blocks, screw-clamp type

Structural Characteristics:

• Form Factor: DIN rail mountable module
• Dimensions (W x H x D): 25 mm x 120 mm x 110 mm (approximate)
• Weight: Approximately 150 grams
• Mounting: Standard 35 mm DIN rail (EN 60715)

Working Principle:
The RC27-1840 receives a raw 4–20 mA signal from a field transmitter. The input signal passes through an isolation amplifier that provides galvanic separation. The conditioned signal is then scaled, filtered, and output as a standardized 4–20 mA or 1–5 V signal to the I/A Series controller. The module derives its operating power from the 24 V DC bus and simultaneously provides loop power to the field transmitter.

Advantages / Highlights:

• High isolation rating of 1500 V DC ensures noise immunity and ground loop elimination
• Built-in loop power supply eliminates need for external power for 2-wire transmitters
• Compact DIN rail form factor saves panel space
• Diagnostic LEDs provide immediate fault visibility
• Wide operating temperature range suitable for harsh industrial environments

Applicable Industries:

• Oil and Gas (upstream/midstream/downstream)
• Chemical and Petrochemical Processing
• Power Generation (fossil and nuclear)
• Water and Wastewater Treatment
• Pulp and Paper
• Mining and Minerals Processing

Installation Requirements:

• Mount on 35 mm DIN rail inside the I/A Series I/O cabinet
• Maintain minimum 10 mm clearance above and below the module for ventilation
• Ensure 24 V DC power bus is connected to terminals P+ and P-
• Field wiring connects to IN+ and IN- terminals
• System output connects to OUT+ and OUT- terminals
• Use shielded twisted pair cable for all analog signal connections
• Ground the cable shield at one end only (system side)

Usage Precautions:

• Do not exceed 30 V DC on the power supply input
• Do not connect voltage signals to current input terminals (will damage the module)
• Verify correct input range configuration before commissioning
• Ensure proper torque on terminal screws (0.5–0.8 Nm)
• Replace the module immediately if diagnostic LED indicates fault