What Is SCADA? Supervisory Control Without Replacing the PLC
SCADA sits above PLCs and RTUs: it acquires field data, alarms operators, and issues supervisory commands across plants and remote assets—without replacing local deterministic control.



The Bently Nevada 125720-01 is a spare 4-channel relay I/O module designed for use within the 3500/32 4-Channel Relay Module system. Installed in a full-height rear slot of a 3500 rack, it provides the physical terminal interfaces to route switching outputs to external control or machinery protection equipment.
The 125720-01 I/O module operates in conjunction with the front 3500/32 relay main module. Each of its four channels uses two single-pole, double-throw (SPDT) relays wired in a double-pole, double-throw (DPDT) configuration. Individual channels can be configured independently for Normally De-energized or Normally Energized operations and include onboard switches to select relay modes alongside standard 250 Vrms arc suppressors and epoxy environmental sealing.
| Parameter | Specification |
|---|---|
| Manufacturer | Bently Nevada |
| Country of Origin | U.S.A |
| Module Type | Spare 4-Channel Relay I/O Module |
| Relay Type | Two SPDT relays connected in a DPDT configuration per channel |
| Environmental Sealing | Epoxy-sealed |
| Arc Suppressor | 250 Vrms, installed as standard |
| Contact Life | 100,000 cycles @ 5 A, 24 Vdc or 120 Vac |
| Operation Modes | Switch selectable per channel for Normally De-energized or Normally Energized |
| Max Switched Power (Resistive) | DC: 120 W; AC: 600 VA |
| Min Switched Current | 10 mA @ 5 Vdc |
| Max Switched Current | 5 A |
| Max Switched Voltage | DC: 30 Vdc; AC: 250 Vac |
| Operating Temperature | -30 degC to +65 degC (-22 degF to +150 degF) |
| Storage Temperature | -40 degC to +85 degC (-40 degF to +185 degF) |
| Humidity | 95%, non-condensing |
| Dimensions (H x W x D) | 241 mm x 24.4 mm x 99.1 mm (9.50 in x 0.96 in x 3.90 in) |
| Weight | 0.4 kg (1.0 lb.) |
| Rack Space Requirements | 1 full-height rear slot |
| Certification / Standard | Detail |
|---|---|
| Safety Requirements | EN 61010-1 |
| EMC Directives | IEC 61000-6-4 (Radiated/Conducted EN 55011 Class A), IEC 61000-6-2 (EN 61000-4-2, ENV 50140, ENV 50141, EN 61000-4-4, EN 61000-4-5, EN 61000-4-8, EN 61000-4-11, ENV 50204) |
| Hazardous Area Approvals | CSA/NRTL/C (Class I, Div 2, Groups A, B, C, D; T4 @ Ta = -20 degC to +65 degC) |
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| Color pattern |
Greyish White
|
| Country of origin |
United States
|
| Power source |
DC Power
|