Foxboro RH926ZY | Fieldbus Power Conditioner 24V DC 100mA In Stock
Foxboro RH926ZY | Fieldbus Power Conditioner 24V DC 100mA In Stock - Image 2
Foxboro RH926ZY | Fieldbus Power Conditioner 24V DC 100mA In Stock - Image 3

Foxboro RH926ZY | Fieldbus Power Conditioner 24V DC 100mA In Stock

  • Model: RH926ZY
  • Brand: Foxboro (Invensys / Schneider Electric)
  • Series: I/A Series Fieldbus Power Conditioner (FPC)
  • Core Function: This module takes standard 24V DC power and converts it into a conditioned, short-circuit protected supply specifically for H1 Foundation Fieldbus devices.
  • Type: Power Supply / Power Conditioner Module
  • Key Specs: 24V DC Input, 100mA Output (typical), Short-circuit protection.
Category: SKU: FOXBORO RH926ZY

Description

Key Technical Specifications

  • Input Voltage: 24V DC (Nominal), typically 19.2V to 31.2V operating range
  • Output Current: 100mA (Maximum continuous per channel)
  • Output Voltage: Regulated for H1 Fieldbus segment (typically ~9V DC under load)
  • Power Dissipation: < 2.5 Watts (at full load)
  • Short Circuit Protection: Current limited and auto-recovering
  • Isolation: Galvanic isolation between input and fieldbus output
  • Mounting: DIN Rail (Standard I/A Series mounting footprint)
  • Environmental: 0 to 60°C (32 to 140°F) operating temperature
  • Termination: Pluggable terminal blocks (Euro-style)
  • Indicator: LED status for Power and Fault conditions

Product Introduction

Let’s be real—Fieldbus segments are notoriously sensitive to dirty power. If you pump raw 24V DC straight into your transmitters without proper conditioning, you’re going to see communication dropouts that will drive you crazy during commissioning. That’s exactly where the Foxboro RH926ZY comes in. It’s a dedicated Fieldbus Power Conditioner (FPC) designed for the I/A Series ecosystem, ensuring your H1 instruments get clean, regulated power without the electrical noise.The main reason veteran engineers stick with this module is its rugged current-limiting design. It delivers a steady 100mA, which is usually enough to drive a small segment of 4-6 field devices depending on their quiescent current draw. I’ve seen these sit in scorching marshalling cabinets for over a decade without breaking a sweat. Just keep in mind, the LED diagnostics are basic—green is good, off is bad—so don’t expect fancy digital readouts on the front face.

 

Quality SOP & Tech Pitfalls (The Reality Check)

The Lab Report (SOP)
Before we ship this out, we run it through a strict gauntlet so you don’t have to debug it at 2 AM:

  1. Visual Inspection: We check the PCB for any signs of moisture damage or capacitor swelling, and verify the Foxboro branding is legitimate (no cheap knock-offs).
  2. Live Bench Test: We hook it up to a stabilized 24V DC supply and measure the output voltage under a dummy load to ensure it regulates correctly to Fieldbus specs.
  3. Short-Circuit Simulation: We intentionally short the output to verify the current-limiting protection kicks in immediately and resets automatically once the short is removed.
  4. Insulation Check: A quick check with a multimeter to ensure there’s proper galvanic isolation between the input and output terminals.
  5. Packaging: It goes into an anti-static bag, wrapped in bubble wrap, and boxed tight to survive the courier toss.

The Engineer’s Warning (Pitfalls)

  • Don’t overload the segment: This module is rated for 100mA. If you daisy-chain too many power-hungry valves or old transmitters on one FPC, it will current-limit and your whole segment will go offline. Always calculate your total quiescent current first.
  • Polarity matters: While Fieldbus is somewhat forgiving, reversing the input power on the wrong terminals can blow the internal fuse or protection diodes. Double-check your 24V DC wiring before snapping it onto the DIN rail.
  • Grounding loops: Since this provides isolation, make sure you aren’t creating a ground loop elsewhere in the shield wiring. I once spent three days chasing a “ghost” communication error that turned out to be a grounding issue, not the power conditioner itself.

 

Installation & Configuration Guide

Swapping this module is straightforward, but follow these steps to avoid tripping the whole rack.

  1. Pre-Installation
    • ⚠️ Safety First: Identify the 24V DC source breaker and switch it OFF. Verify with your multimeter that there is zero voltage at the terminal block.
    • Take a photo of the existing wiring if you are doing a direct swap.
  2. Removal
    • Disconnect the input power wires and the Fieldbus segment wires. Label them clearly (Input + / Input – / Fieldbus + / Fieldbus -).
    • Use a flathead screwdriver to release the DIN rail locking clip at the bottom of the module, then pull it straight out.
  3. Installation
    • Check the Part Number: Ensure the new RH926ZY matches the old one exactly.
    • Hook the top of the module onto the DIN rail and snap the bottom into place. It should feel solid, no wobbling.
    • Reconnect the wiring: 24V DC Input first, then the Fieldbus segment output. Tighten the screws—vibration loosens them over time.
  4. Power-On & Testing
    • Turn the 24V DC breaker back ON.
    • Check the LED indicator on the front. It should light up (usually green) indicating power is present.
    • Go to your control system (I/A Series workstation) and verify that the Fieldbus devices on that segment are reporting “Good” status and not “Comms Fail.”

 

Compatible Replacement Models

  • ✅ Drop-in Replacement: Foxboro RH926ZY. This is the exact part. If you have this model number, just swap it.
  • ⚠️ Functional Equivalent: Pepperl+Fuchs K-System or H-System Fieldbus Power Supplies (e.g., KFD2-FC-Ex1). Note: These are excellent units, but they are not a direct physical footprint match. You will need to modify the DIN rail space and rewire the terminals.
  • ❌ Not Compatible: Foxboro MBM (Main Bus Module) or standard 24V DC PSUs. Do not try to replace an FPC with a generic power supply; you will fry your Fieldbus instruments due to lack of signal conditioning and current limiting.

Frequently Asked Questions (FAQ)

Q: Can I hot-swap this module while the system is running?
A: Technically, the I/A Series hardware supports hot-swapping, but I wouldn’t recommend it for a power module unless you have to. Pulling it out will kill power to that entire Fieldbus segment, causing all connected transmitters and valves to fault instantly. If the process can handle the outage, go for it; otherwise, schedule a downtime.Q: My LED is off, but I have 24V at the input terminals. Is the module dead?
A: Most likely, yes. Or the internal protection has tripped. Disconnect the Fieldbus output wires (the load) and power cycle it. If the LED comes back on with no load connected, your issue is a short circuit in the field wiring, not the module. If it stays off with no load, the RH926ZY is toast.Q: How many devices can I run off one RH926ZY?
A: It depends entirely on the current draw of your devices. The module gives you 100mA max. If your transmitter takes 12mA and your valve positioner takes 20mA, do the math. I usually leave a 20% safety margin, so plan for about 80mA of usable capacity to be safe.Q: Does this come with the terminal blocks?
A: Yes, if you buy it new or as new surplus, the pluggable terminal blocks should be attached or included in the box. If you’re buying used bulk, check if the green plugs are there—you don’t want to have to scavenge them from an old spare.Q: Is this the same as the RH926ZJ?
A: No. Foxboro part numbers are very specific. The suffix matters. The RH926ZY is configured for specific Fieldbus power conditioning requirements. Always cross-reference the full part number with your system BOM (Bill of Materials) before ordering.

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