How to Wire a Schneider Shunt Trip Breaker Step-by-Step Guide with Diagram
For Schneider protection relays requiring remote activation, the auxiliary release coil must connect directly to the designated 96 and 95 terminals–polarity matters. Verify voltage compatibility: standard models (e.g., GV2, GV3) accept 24-240V AC/DC, but compact variants like NSX may demand 12-60V. Always cross-reference the device’s technical insert (e.g., “FD” suffix for 120V, “FH” for 240V) before wiring. Incorrect voltage triggers immediate coil burnout, voiding warranty.
Use minimum 1.5mm2 copper conductors for coil connections, even if the control circuit operates at low amperage. Thin wiring (e.g., 0.75mm2) risks voltage drop under sustained loads, causing delayed tripping. Route control cables at least 10cm from power lines (>10A) to prevent induced interference, which can lead to false activations. Schneider’s Micrologic trip units with LSIG protection add complexity–consult the DOC-20280 manual for auxiliary circuit isolation requirements.
For fail-safe operation, pair the auxiliary coil with a maintained pushbutton or PLC output–momentary pulses won’t suffice. Schneider’s TELEMECANIQUE XB6-EA11 emergency stop buttons integrate seamlessly; connect the NC contacts in series with the coil. Test functionality by applying rated voltage to the coil while verifying instantaneous disconnection. Use a multimeter to confirm 0Ω across closed main contacts pre-activation and open circuit post-trip. Failure at this stage mandates resetting the mechanical latch–refer to the red reset button on the device’s lower front panel.
In multi-panel setups, isolate control circuits using Schneider’s RXM4AB2BD relay for signal amplification. Avoid daisy-chaining coil circuits; each protection device should have a dedicated control path. For AC applications above 20A, install a 1N4007 diode across the coil to suppress voltage spikes. Schneider’s ComPact series (NSX, NS) includes embedded surge protection, but third-party auxiliary coils don’t–add external suppression if mixing brands.
Connecting Auxiliary Release Coils in Schneider Electrical Protection Devices
To wire an auxiliary release coil in a Schneider protection unit, start by identifying terminals labeled X1 and X2 on the device’s control module. These correspond to the coil’s power input–typically rated for 24V DC, 110V AC, or 230V AC, depending on the model. Refer to the product datasheet (e.g., Masterpact NT/NW or Compact NSX) for exact voltage compatibility. Connect the positive lead to X1 and the negative/neutral to X2, ensuring polarity matches the specified voltage type.
For remote activation, integrate a pushbutton or relay between the control circuit and the coil. Use a normally open (NO) contact configuration:
- Wire the relay’s common (COM) to the power source (e.g., 24V DC).
- Connect the relay’s NO terminal to X1.
- Ground or return the circuit to X2, completing the loop.
Avoid paralleling multiple coils unless explicitly permitted in the manual–Schneider’s Micrologic series, for example, prohibits this due to risk of false triggering.
Critical Safety Checks Before Energizing
Inspect connections for:
- Voltage mismatch: Applying 230V to a 24V coil will destroy it instantly. Verify ratings with a multimeter.
- Loose terminals: Torque screws to Schneider’s specified values (e.g., 2.5 Nm for NSX) to prevent arcing.
- Short circuits: Test continuity between X1 and X2 with the circuit de-energized–reading
For AC coils, confirm waveform integrity; use a sine-wave supply–modified square waves (e.g., from VFD outputs) can overheat the coil.
Label all wires with heat-shrink tubing or Schneider’s EverLink adhesive tags. Document the setup in a schematic using IEC 60617 symbols:
- Coil: Rectangle with diagonal line.
- NO contact: Parallel lines, broken in center.
- Power source: Battery symbol (IEC: / / /).
Attach the schematic to the enclosure door for maintenance reference. For troubleshooting, Schneider’s EcoStruxure Power software can log coil activation events if the device includes communication modules like ComPacT or PowerLogic.
Selecting Matching Auxiliary Release Units for Schneider Circuit Protectors
Check the device series first – the ComPact NSX range supports the MN or MX auxiliary release modules, while the Acti9 iC60 lineup pairs exclusively with the iMX or iMN units. Verify the voltage rating: 24V DC models like the MX 24V are incompatible with 230V AC systems, requiring instead the MX 230V or similar variants. Always cross-reference the catalog number on the manufacturer’s compatibility matrix to avoid mismatches.
The physical dimensions of the release module must align with the base unit’s frame size. For example, the NSX100 allows only compact MN/MX modules, whereas the NSX250 accepts wider units like the MX+OF. Installing an oversized module risks mechanical interference with adjacent components, particularly in panel-mounted configurations where clearance is minimal.
Review the control signal requirements – some modules (e.g., iMX) need a maintained voltage pulse, while others (like MN 24V) operate on a momentary trigger. The iMN series includes an integrated position contact, eliminating the need for external auxiliary switches in most applications. Always test the module’s response time under load; variations between 20ms and 80ms can impact coordination with other protective devices.
Consult the technical datasheet for the interrupting capacity – modules like the MX 230V handle up to 10kA, but lower-rated units (e.g., iMX) cap at 6kA. Ensure the selected module’s short-circuit performance matches or exceeds the system’s prospective fault current. For installations in harsh environments, prioritize models with conformal coating (e.g., NSX-MX-UC) to prevent corrosion from humidity or chemical exposure.
Replace obsolete models with direct successors: the MX08-DC replaces the older MX-D, and the MX+OF supersedes the MX+SD. For legacy systems, verify pin compatibility – some newer modules require adapter kits for installation in older base units. Always power down the entire circuit before swapping modules to avoid accidental activation of the release mechanism.
Step-by-Step Connection Procedures for Auxiliary Release Units by Schneider Electric
Begin by verifying the control voltage compatibility with the auxiliary release unit’s specifications. Schneider Electric’s separable actuation modules typically support 24V DC, 120V AC, or 230V AC–match the control circuit’s output precisely. A mismatch risks faulty operation or permanent damage. Check the product datasheet under the “Control Voltage” section; deviations beyond ±10% of the nominal value require a dedicated power supply or transformer.
Identify the input terminals on the actuation module: they are labeled “A1” (positive) and “A2” (negative) for DC, or “L” (live) and “N” (neutral) for AC. Strip 6–8 mm of insulation from the control wires, ensuring no stray strands remain. Twist the strands lightly before insertion to prevent short circuits. Tighten terminal screws to 1.2 Nm–exceeding this torque can strip the threads, while insufficient torque causes loose connections and intermittent failures.
For a remote triggering setup, integrate a normally open push button or relay contact between the control source and the actuation module. The push button’s contacts must handle the module’s inrush current–typically 5A for 24V DC versions. Schneider’s phase-sensitive modules draw a brief 15A spike during activation; undersized contacts will weld shut. Use a relay rated for at least 10A resistive if the control circuit is low-current.
Terminal Pairing Guide for Common Configurations
| Control Source | Module Terminal | Wire Gauge (mm²) | Notes |
|---|---|---|---|
| 24V DC supply | A1 (+) to positive, A2 (-) to negative | 0.75–1.5 | Polarity reversal destroys the module |
| 120V AC transformer | L to live, N to neutral | 1.0–2.5 | Verify transformer capacity ≥10VA |
| PLC digital output | A1 to DO+, A2 to DO- | 0.5–1.0 | Series resistor 1kΩ if PLC output is |
Route control wiring away from power conductors carrying currents above 10A. Maintain a minimum 50 mm separation or use shielded cable for runs exceeding 3 meters. Unshielded wires picking up inductive noise from adjacent motors or contactors can cause false triggering. Ground the shield at one end only to avoid ground loops; Schneider’s documentation specifies the shield drain wire should connect to the panel’s earth busbar, never the neutral.
After connecting the control circuit, attach the auxiliary release unit’s output terminals to the protective device’s dedicated slot. The output terminals are marked “C” (common) and “NO” (normally open). A jumper wire bridges “C” and “NO” when the module is inactive; activation opens the contact. For fail-safe applications, wire an external alarm to the “NO” terminal–this contact closes during module operation, signaling a triggered state. Ensure the alarm coil or indicator matches the module’s contact rating: 250V AC / 30V DC, 5A resistive.
Test the assembly in a controlled environment before commissioning. Apply the nominal control voltage and monitor the protective device’s instantaneous response. Schneider’s separable modules react in 20–50 ms; delays outside this window indicate wiring errors or undersized conductors. Use a multimeter in continuity mode to confirm the “C-NO” contact opens promptly. Log test results: date, voltage applied, response time, and observed behavior. These records simplify troubleshooting during future maintenance cycles.
Common Pitfalls and Corrective Actions
Loose terminal screws: Re-torque to 1.2 Nm and coat with anti-vibration compound if the installation is subject to mechanical shock. Incorrect polarity on DC modules: Replace the module–the internal MOV is non-polarized but the driving transistor is not. Noise-induced false triggers: Route control wires in separate conduit and enable the module’s built-in 1 ms debounce delay via DIP switch #3. Overheating: Reduce ambient temperature below 60°C or derate the module per Schneider’s temperature curves–continuous operation at 70°C halves the module’s lifespan.