Generic LJ30A3-15-Z/BX Inductive Proximity Sensor, NPN NO, 15mm Range, 6-36VDC, IP65, Non-Shielded

The NPN Normally Open (NO) output means the sensor's signal wire (typically black) is internally switched to ground (0V) when a metal target is detected within range. In the absence of a target, the output is in a high-impedance (open) state. This is the standard sinking input for most PLCs. A Normally Closed (NC) output would be the opposite, providing a continuous ground signal that opens when a target is detected, often used for fail-safe circuits.

Connect the brown wire to your positive DC supply (6-36VDC), the blue wire to the DC common (0V/GND), and the black wire (signal output) to your PLC's digital input. The PLC input must be configured as a sinking input (i.e., it provides an internal pull-up resistor to +24V). When the sensor detects metal, the black wire switches to ground (0V), completing the circuit and activating the PLC input. Always ensure your power supply voltage matches the sensor's operating range.

A non-shielded (or unthreaded) sensor has its sensing coil exposed at the sides of the barrel. This allows for a larger lateral sensing field, enabling detection from the side and providing more mounting flexibility. However, it also means the sensor can be influenced by adjacent metal objects. During installation, maintain the recommended clearance distances (typically 2x the sensor diameter) from surrounding metal to prevent false triggering and ensure the specified 15mm sensing range is achieved.

Yes, inductive sensors detect all conductive metals, but with varying effective ranges. Ferrous metals (like steel and iron) are detected at the full nominal range (15mm). Non-ferrous metals (like aluminum, copper, brass) have a reduced effective sensing distance, typically 30-60% of the nominal range. The recommended setting distance (the gap between the sensor face and the target) is 0-12mm for reliable operation and to account for mechanical tolerances, thermal expansion, and potential target wear.