Description
Socomec W4-S140 | Rectangular Residual Current Transformer In-Stock
Dynamic Product Introduction
Operating high-power busbar distribution systems or heavy industrial electrical panels without accurate earth leakage monitoring introduces severe arc fault risks and unexpected main breaker trips. The Socomec W4-S140 (P/N: 49505140) is a high-sensitivity rectangular measuring current transformer engineered specifically for residual current monitoring (RCM) and earth fault protection loops. Featuring a generous 140 mm x 300 mm inner window opening, it seamlessly accommodates massive copper busbar runs or high-gauge multi-conductor cable groups, detecting minute vector current imbalances down to the milliamp level without saturation.
When an operational current sensor suffers terminal block fracture, internal winding insulation breakdown, or magnetic core distortion from physical impact, sourcing an exact-fit Socomec W4-S140 replacement unit restores electrical safety loops immediately. Installing a fully bench-tested replacement transformer allows electrical maintenance teams to mount the sensor directly around existing busbar runs without re-engineering enclosure mounting frames or altering relay trip response curves. Swapping out a compromised sensor restores continuous ground fault surveillance, precise leakage current evaluation, and total plant power quality compliance.
W4-S140
Key Technical Specifications
- Model Designation: W4-S140
- Order Reference: 49505140
- Manufacturer: Socomec Group
- System Compatibility: Socomec RESYS P40 / P50 / M40 Series Residual Current Relays
- Inner Window Dimensions: 140 mm x 300 mm (5.51 in x 11.81 in)
- Sensor Type: Type A differential current transformer (detects AC and pulsating DC ground fault currents)
- Rated Insulation Voltage: 800 VAC nominal
- Transformation Ratio: High-accuracy secondary output ratio calibrated for Socomec RESYS evaluation electronics
- Secondary Connection: Integrated screw-clamp terminal block with protective shield cover
- Operating Temperature Range: -10°C to +55°C (14°F to 131°F)
- Storage Temperature Range: -25°C to +70°C (-13°F to 158°F)
Global Sourcing & Live-Test SOP (Transparency Core)
Procuring secondary-market electrical safety sensors like the Socomec W4-S140 requires rigorous bench diagnostic screening to verify magnetic core permeability, ratio accuracy, and output signal linearity. Every incoming transformer passes through an intensive five-stage quality assurance protocol:
- Inbound Verification: Part numbers (W4-S140 / 49505140), serial badges, and housing structural integrity are validated against original Socomec manufacturing standards. Technicians examine the internal core window, mounting points, and terminal block screws for signs of mechanical fatigue or thermal stress.
- Live Simulation: The W4-S140 is placed on a high-current diagnostic test stand equipped with primary current injection loops and wired to a calibrated Socomec RESYS monitoring relay.
- Diagnostics: Technicians pass precision multi-turn primary conductor loops through the 140 x 300 mm window, injecting simulated differential fault currents from 30 mA up to 10 A. The sensor’s secondary signal output linearity, phase displacement, and frequency response are measured to ensure zero measurement drift. The unit then undergoes a 24-hour thermal soak in an environmental chamber to confirm winding resistance stability.
- Final Prep: Secondary terminal screws are cleaned and treated with non-conductive electrical protectant, protective covers are verified, and the transformer is sealed inside static-shielding ESD packaging before freight dispatch.
The Field Engineer’s Pitfall Guide
- ❗ Omitting the Neutral Conductor From the Sensor Window: —though you might expect standard CT installation rules, passing only the phase conductors through the window on a 4-wire system while routing the neutral conductor outside will create massive false vector imbalance readings, causing immediate nuisance trips on the RESYS relay.
- ❗ Routing Protective Earth (PE) Grounding Conductors Through the Window: Passing a metallic enclosure PE ground strap back through the inner window cancels out the magnetic flux generated by downstream fault currents, rendering the Socomec protection system completely blind to real ground faults.
- ❗ Over-Torquing Secondary Connection Terminals: Excessive torque applied to the secondary signal output terminals can strip internal mounting threads or crack internal PCB contact pads, causing open-circuit faults on the signal line.
Intent-Driven FAQ
What is the primary function of the Socomec W4-S140 current transformer?
The W4-S140 detects differential residual (earth leakage) currents across phase and neutral conductors in heavy power distribution networks, outputting proportional signals to Socomec RESYS protection relays.
Can the W4-S140 be used for standard current metering or ammeter inputs?
No. The W4-S140 is a specialized residual current transformer designed strictly for ground fault protection and insulation monitoring. It is not rated or calibrated for standard phase current measurement or power metering instrumentation.
What causes a “CT Disconnection” alarm on the connected Socomec RESYS relay?
A “CT Disconnection” or wire-break fault indicates an open circuit, high contact resistance, or severed cable along the secondary wiring between the W4-S140 output terminals and the evaluation relay input ports.
Does the Socomec W4-S140 require an external auxiliary power supply?
No. The W4-S140 is a passive current transformer that generates its secondary signal directly from the magnetic flux imbalance of the monitored primary conductors. The connected RESYS relay provides all required evaluation power.
What warranty coverage comes with pre-inspected replacement current transformers?
All verified Socomec W4-S140 residual current transformers come backed by a comprehensive 1-year replacement warranty. If the unit experiences core saturation drift, winding open circuits, or output signal loss under standard operating conditions within 12 months, it is swapped directly from available warehouse inventory stock.
