Description
NK Technologies AG1-SDT1-24U-DEN-A55 | Ground Fault Relay
Dynamic Product Introduction
Protecting personnel, sensitive machinery, and electrical processes from harmful ground fault conditions requires reliable monitoring of current-carrying conductors. The NK Technologies AG1-SDT1-24U-DEN-A55 utilizes the “zero sum” operating principle, wrapping around system conductors to detect minute current imbalances caused by tracking or leakage to ground.
Configured with a 24 VAC/VDC power supply requirement and a Normally De-energized relay state with auto-reset, this specific build incorporates a custom factory-calibrated setpoint (-A55). When replacing or installing ground fault protection hardware, always ensure the trip threshold and control voltage match your exact system specification to avoid nuisance tripping or unprotected fault vectors.
AG1-SDT1-24U-DEN-A55
Key Technical Specifications
| Parameter | Specification Detail |
| Primary Architecture | AG Series Ground Fault Sensor & Relay Module |
| System Compatibility | Grounded single-phase and three-phase (delta or wye) electrical systems |
| Sensing Principle | “Zero Sum” magnetic field cancellation (monitors all current-carrying conductors) |
| Setpoint Range | AG1 tier (Factory calibrated setpoint configuration, denoted by -A55 suffix) |
| Output Type | SDT1: SPDT Form C Mechanical Relay with Auto-Reset |
| Control Power | 24 VAC / VDC (-24U configuration) |
| Relay State Mode | Normally De-energized (-DEN configuration) |
| Enclosure & Mounting | Solid-core case with screw terminals, DIN-rail or panel mount options |
Global Sourcing & Live-Test SOP
Sourcing surplus electrical safety and ground fault monitoring devices requires rigorous verification of relay coils, internal microprocessors, and magnetic core integrity:
- Inbound Verification: Part numbers, suffix codes (
-SDT1-24U-DEN-A55), and data plates are audited against factory specifications to verify authentic NK Technologies construction. - Visual Audit: Enclosures, terminal blocks, and internal pass-through aperture rings are inspected for physical cracks, terminal screw stripping, or accumulation of debris.
- Live Bench Simulation: The unit is powered using a calibrated 24V source. Primary test conductors are passed through the sensing window to simulate balanced loads and controlled ground fault imbalances.
- Diagnostics & Prep: The SPDT mechanical relay contact closure response time and trip threshold are verified against the specific factory calibration parameters. Approved units are cleaned, screw terminals are capped, and units are sealed in heavy-duty anti-static moisture-barrier packaging.
The Field Engineer’s Pitfall Guide
❗ Passing the Equipment Ground Wire: Passing the protective earth (ground) conductor through the sensor window alongside the hot/neutral lines will cause total cancellation of the magnetic field, blinding the device to actual ground faults. Only current-carrying conductors (phase and neutral) should pass through the core.
❗ Control Power Voltage Mismatches: Applying 120V AC control power to a unit built specifically for 24 VAC/VDC (-24U) operation will immediately damage the internal power regulation circuitry.
❗ Conductor Size Limitations: Ensure the physical bundle of monitored wires fits comfortably inside the solid-core aperture window without aggressive pinching or forcing, which can damage cable insulation.
Intent-Driven FAQ
What does the “-A55” suffix designate on this model?
The “-A55” suffix denotes a specific factory-calibrated trip setpoint tailored to meet precise application requirements within the AG1 operating range.
Can the AG1-SDT1-24U-DEN-A55 be used on three-phase systems?
Yes. The sensor can monitor single-phase or three-phase (delta or wye) grounded systems as long as all current-carrying conductors pass through the sensing window.
What is the advantage of a Normally De-energized (-DEN) output?
In a normally de-energized configuration, the relay changes state only when a ground fault exceeding the setpoint is detected, making it ideal for signaling automated control systems or energizing shunt trip breakers.
Does this unit require an external power supply?
Yes. Unlike self-powered loop sensors, the -24U designation indicates that the unit requires an external 24 VAC or VDC control power source to operate its internal electronics and relay coil.
What warranty covers surplus NK Technologies units?
Every unit delivered from our inventory is backed by a comprehensive 12-month operational warranty covering relay switching health, sensing core accuracy, and power supply stability.
