Bently Nevada 3500/32 125720-01 4-Channel Relay Rear I/O Module

Description

Key Technical Specifications

Product Introduction & Supply Chain Strategy

The Bently Nevada 3500/32 125720-01 is the full-height rear I/O card that houses the physical screw-terminal connections for the 3500/32 4-channel relay system. Installed in the back of the 3500 rack directly behind the front control card (125712-01), it provides epoxy-sealed contact terminations and onboard 250 Vrms arc suppressors to route trip interlocks directly to plant Safety Instrumented Systems (SIS).

Maintaining verified New Surplus 125720-01 rear modules in critical stock avoids catastrophic machine shutdown delays during hardware swap-outs. Reusing second-hand or refurbished terminal cards risks high electrical resistance, stripped terminal screws, or pitted contact pins, which can fail to break a safety loop during an emergency or cause accidental open-circuit trips.

Installation & Configuration Guide

Stage 1: Pre-Installation (Prep & Safety)

1. Ensure the field trip loops connected to the rear module are isolated or placed in manual bypass at the main control room panel.
2. Put on a grounded anti-static wrist strap connected to the cabinet ground.
3. Label all incoming field wires (Normally Open, Normally Closed, Common for each channel) to prevent terminal pinout mix-ups during re-wiring.

Stage 2: Removal

1. Unplug or unbolt the green terminal block headers from the rear 125720-01 panel using a flat-head terminal screwdriver.
2. Loosen the upper and lower captive screws on the 125720-01 faceplate.
3. Pull the module straight back out of the chassis slot using the ejection handles, avoiding lateral twist that could damage adjacent backplane pins.

Stage 3: Installation (Clone & Seat)

1. Inspect the card edge gold fingers on the new 125720-01 board for contamination, debris, or damaged traces.
2. Align the 125720-01 module with the rear card guides corresponding directly to the slot containing the front 3500/32 main module.
3. Slide the card in firmly until the rear panel sits flush against the 3500 chassis frame.
4. Tighten the captive mounting screws securely to maintain continuous chassis shield grounding.

Stage 4: Power-On & Testing

1. Reinsert the green terminal connectors into the 125720-01 board.
2. Verify contact continuity across channels using a digital multimeter while performing a software channel test from the front 3500/32 card.
3. Remove safety bypasses and return the trip interlock loop to full active protection mode.

3500/32 125720-01

3500/32 125720-01

Firmware/Software Versions & Upgrade Notes

• Passive Architecture: The 125720-01 module is a passive rear interface board containing field wiring terminals, contact traces, and arc suppression circuits. It holds no digital microprocessor or firmware.
• System Mapping: Relay operation settings (Normally Energized vs. Normally De-energized and AND/OR voting logic) are set via the front-facing 3500/32 card using 3500 System Configuration Software.
• Compatibility Notice: The 125720-01 is designed specifically for standard internal termination systems. Verify whether your installation uses standard internal termination (125720-01) or hazardous area / external termination variants (such as 125720-02) before performing a hardware swap.

Frequently Asked Questions (FAQ)

Is this 125720-01 module genuinely new, or is it a pulled/refurbished part?

This product is a Brand New Surplus unit. It is not used, not pulled from a decommissioned plant, and not refurbished. All modules undergo strict quality verification to ensure OEM-level performance. Original anti-static packaging is retained and opened solely for physical verification and anti-static inspection before delivery.

What is the difference between the 125712-01 and the 125720-01 part numbers?

The 125712-01 is the front main control module containing the primary processing logic and status LEDs, while the 125720-01 is the rear I/O module containing the physical terminal blocks for external field wiring. A complete 3500/32 relay channel slot requires both modules to function.

Does the 125720-01 rear module include built-in arc suppression?

Yes, the 125720-01 module comes equipped with factory-installed 250 Vrms arc suppressors as standard on all output channels. This protects the relay contacts from high-voltage inductive spikes caused by solenoids, motor starters, or trip coils.

What is the difference between 125720-01 and 125720-02?

The 125720-01 is the standard 4-channel relay I/O module designed for general industrial and functional safety systems. The 125720-02 option is specialized for hazardous area installations requiring specific agency approvals or intrinsic safety barrier interface capabilities.

Can I disconnect field wiring from the 125720-01 without turning off the entire 3500 rack?

Yes, the green terminal headers can be unplugged directly from the rear card faceplate. However, ensure your field trip circuit is placed in a safe or bypassed state before unplugging, as disconnecting a Normally Energized (fail-safe) relay loop will open the circuit and trip connected equipment.

What warranty coverage is included with this New Surplus I/O module?

We provide a comprehensive 1-year replacement warranty on all New Surplus Bently Nevada hardware. If the 125720-01 module experiences any electrical fault or terminal defect within 12 months under standard operating conditions, we replace the unit immediately from available stock.