Key Technical Specifications
- Product Model: AG1-SDT1-24U-DEN-A55
- Manufacturer: NK Technologies
- Product Type: Ground Fault Sensor
- Power Supply: 24V AC/DC
- Output Type: SPDT Relay (Form C)
- Mounting: DIN Rail
- Application: Circuit & Load Protection
- System Type: Single/Three-Phase Delta or Wye
- Setpoint Range: Verify with OEM datasheet (e.g., 5-30mA typical for AG series)
- Condition: Refurbished / Tested
Product Introduction
NK Technologies AG1-SDT1-24U-DEN-A55 is a ground fault sensor designed to protect electrical systems from damage caused by low-current ground faults. It monitors all current-carrying conductors in grounded single- and three-phase systems to detect leakage before it causes equipment failure or safety hazards.This sensor provides a SPDT relay output that can be wired into PLCs, HMIs, or alarm circuits for immediate notification or automated shutdown. Field experience shows these units are critical in preventing costly motor burns and arc flash incidents in industrial panels. Always verify the exact setpoint range and wire bundle diameter against your application requirements before installation.
Installation & Configuration Guide
Preparation (10 min)
Verify the new sensor matches the old one exactly. Check the setpoint range and wire bundle diameter. Ensure you have the correct DIN rail and 24V DC power supply. Confirm the panel is de-energized.Removal (5–10 min)
Isolate the sensor from the circuit. Disconnect power and relay output wires first. Remove the DIN rail clip. Inspect the mounting area for debris or damage. (I once saw a technician leave a loose wire strand in the rail slot — it caused a short during power-up. Always clean the area.)Installation (10 min)
Slide the new sensor onto the DIN rail until it clicks. Route the conductors through the sensor’s aperture. Reconnect power and relay output wires. Verify polarity on the 24V DC supply.Power-On & Test (10 min)
Restore 24V DC power. Check the LED status indicator (typically green for normal, red for fault). Use a test resistor to simulate a ground fault and verify the relay trips at the correct setpoint. Reset the sensor after testing.
Troubleshooting Quick Reference
| Symptom | Probable Cause | Action |
|---|---|---|
| No LED illumination | Power supply fault | Check 24V DC supply and wiring polarity |
| Relay trips immediately | Excessive leakage or wiring error | Verify conductor routing; check for actual ground fault |
| Intermittent tripping | Noise or loose connection | Check wire bundle seating; verify setpoint range |
| Relay fails to trip | Sensor fault or setpoint too high | Test with known fault resistor; verify setpoint |
| LED flashes abnormally | Internal fault | Replace unit; verify firmware compatibility |
Dimensions, Mounting & Wiring Notes
- Dimensions: Verify H×W×D against OEM mechanical drawing (DIN rail standard)
- Mounting: DIN Rail (35mm standard)
- Wiring: Screw terminals; verify torque spec in OEM manual
- Note: Always photograph DIP switches and wire bundle orientation before removal. Ensure all current-carrying conductors pass through the sensor aperture.
FAQ
Will this sensor work with my 480V system?
Yes, but only if the system is ungrounded or high-resistance grounded. This sensor monitors leakage current, not line voltage. Verify your system grounding type with an electrician before ordering.I installed it but the relay won’t reset. What’s wrong?
Check for a persistent ground fault. The sensor will latch if leakage exceeds the setpoint. Use a megohmmeter to test each circuit to ground. If no fault is found, verify the setpoint isn’t set too low for your system’s normal leakage.Is this sensor new or refurbished?
This unit is refurbished and fully tested under simulated operating conditions. It is not factory-sealed new surplus. Function is verified; cosmetic wear may be present.Can I use this for VFD output protection?
No. VFDs require specialized sensors like the AGV series due to high-frequency noise. This sensor is designed for line-frequency applications. Using it on VFD output may cause nuisance tripping.What’s the lead time if you don’t have it in stock?
Typically 3–5 business days for tested units. If you need a specific setpoint range that’s backordered, we’ll tell you upfront rather than ship something incompatible.Do you include a test report?
Yes. Every unit ships with a test record showing relay trip verification at multiple setpoints. No report, no shipment.I’ve never installed a ground fault sensor before. Any tips?
Route all conductors through the aperture — missing one will cause false trips. Keep the sensor away from VFDs or large contactors to avoid noise. And always test with a known resistor before putting the system back in service.
