The Bently Nevada 125720-02 is the Spare 4-Channel Relay Output Module designed specifically for hazardous area (Class I, Division 2 / Zone 2) and functional safety (SIL) systems within the 3500/32M Relay Module architecture. It is a full-height rear I/O card that works in conjunction with the 149986-02 front relay control module, providing four independent Single-Pole Double-Throw (SPDT) relay outputs for machine protection and emergency shutdown logic.
Item No :
125720-02Order(MOQ) :
1 PiecePayment :
EXW/CIFProduct Origin :
USAShipping Port :
WuhanLead Time :
3-5daysWeight :
3kg| Specification | Description |
|---|---|
| Manufacturer | Bently Nevada (Baker Hughes) |
| Model | 125720-02 |
| Product Family | 3500/32M 4-Channel Relay Module |
| Product Type | Spare 4-Channel Relay Output Module (Rear I/O) |
| Compatible Front Module | 149986-02 (4-Channel Relay Control Module) |
| Application | Hazardous area systems and functional safety (SIL) systems |
| Number of Outputs | 4 independent relay channels |
| Relay Type | Single-Pole Double-Throw (SPDT / Form C) |
| Contact Life | 100,000 cycles @ 5 A, 24 Vdc or 240 Vac |
| Max Switched Voltage (Hazardous/SIL) | 30 Vdc / 30 Vac (voltage-restricted for certification compliance) |
| Max Switched Current | 2 A (resistive load) @ 30 Vdc / 30 Vac |
| Min Switched Current | 100 mA @ 12 Vdc |
| Arc Suppressor | 250 Vrms, standard installed |
| Isolation | Epoxy-sealed relay construction |
| Operating Mode | Switch-selectable Normally Energized (NE) or Normally De-energized (NDE) |
| Power Consumption | 5.8 W typical |
| Rack Position | Rear slot directly behind the 3500/32M main module |
| Rack Space | 1 full-height rear slot |
| Dimensions (H x W x D) | 241 mm x 24.4 mm x 99.1 mm |
| Weight | Approx. 0.4–0.48 kg |
| Operating Temperature | -30°C to +65°C (-22°F to +150°F) |
| Storage Temperature | -40°C to +85°C (-40°F to +185°F) |
| Humidity | 95%, non-condensing |
| Certifications | ATEX, IECEx, cNRTLus (Class I, Div 2 / Zone 2) |
| Required Field Connector | 00580436 (6-position green terminal header) or 166M2390 (push-in spring type) |
| Country of Origin | USA |
| Model | Description | Typical Application |
|---|---|---|
| 125720-02 (this model) | Spare 4-Channel Relay Output Module for hazardous/SIL systems | Hazardous area and functional safety applications |
| 125720-01 | Spare 4-Channel Relay Output Module (standard) | General-purpose applications (repair only) |
| 149986-02 | Spare 4-Channel Relay Control Module (front card) | Companion front card for the 125720-02 |
| 3500/32-01-01 | Complete 4-Channel Relay Module (cNRTLus) | North American installations requiring Class I Div 2 |
| 3500/32-01-02 | Complete 4-Channel Relay Module (ATEX/IECEx/CSA) | International hazardous area installations |
| 00580436 | 6-position green terminal header | Required field wiring connector |
| 166M2390 | Push-in spring type terminal header | Alternative field wiring connector |
Q1: What is the primary function of the 125720-02?
It is the rear I/O module for the 3500/32M 4-Channel Relay Module in hazardous area and SIL-rated systems. It provides the physical SPDT relay contacts that execute the trip, alarm, and shutdown logic programmed in the front-panel relay control module (149986-02). It serves as the critical "execution" interface between the monitoring rack and external shutdown devices such as ESD valves and annunciators .
Q2: What is the difference between 125720-02 and 125720-01?
The 125720-02 is the specialized version for hazardous area (Class I, Div 2 / Zone 2) and functional safety (SIL) systems. It is voltage-restricted to 30 Vdc / 30 Vac to comply with certification spacing requirements. The 125720-01 is the standard version for general-purpose applications with higher voltage ratings (up to 125 Vdc / 250 Vac), but it is available for repair only per official spares documentation .
Q3: Can the 125720-02 be hot-swapped?
No. Maintenance personnel must disconnect the field wiring terminal blocks and power down the specific slot area prior to extraction. Removing this hardware under active load can disrupt the safety voting loops and trigger false emergency trips. Always follow proper ESD precautions and verify the replacement module's configuration matches the original .
Q4: What are the contact ratings for the 125720-02 in hazardous/SIL applications?
For hazardous area and SIL applications, the relay contacts are limited to:
Maximum switched voltage: 30 Vdc / 30 Vac
Maximum switched current: 2 A (resistive load)
Minimum switched current: 100 mA @ 12 Vdc
Contact life: 100,000 cycles @ 5 A, 24 Vdc or 240 Vac
Q5: What are the common failure modes and diagnostic alerts for this module?
Common diagnostic alerts include:
Module Not OK: Internal self-diagnostic failure, often due to aging relay coils
Relay Fault: Channel fails to actuate, often from external wiring shorts or contact wear
Relay Readback Mismatch: Contact welding (often caused by inductive load kickback without surge suppression) or coil degradation
Watchdog Timeout: Backplane communication break, often from firmware version mismatches
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