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LJC18A3 liquid level control capacitive proximity switch

LJC18A3 capacitive proximity switch is a non-contact detection device that operates based on the principle of capacitance and is widely used in industrial automation, logistics packaging, liquid level control, and other fields.

Capacitive proximity switches are widely used in:
1. Liquid level control: Detecting the high or low liquid levels in water tanks and oil tanks (can detect through non-metallic container walls or by direct contact with the liquid).
2. Packaging industry: Detecting whether plastic bottles or cartons are in place on the conveyor belt.
3. Woodworking machinery: Detecting wooden boards and furniture components.
4. Powder/grain material level: Detecting whether plastic pellets, grains, or cement powder in silos are full or lacking.
5. Human body sensing: Detecting whether a hand is nearby in some simple automation (though not as safe as dedicated infrared sensors).

product details

Working Principle

The sensing surface of a capacitive proximity switch is composed of two coaxial metal electrodes, which act like the electrodes of a non-linear capacitor and are connected in series within an RC oscillation circuit. When no object is nearby, the RC oscillator does not oscillate. When an object approaches the electrodes, the dielectric constant between the object and the electrodes changes, causing the capacitance to increase and the oscillator to start oscillating. Through subsequent circuitry, the signals of oscillation and non-oscillation are converted into a switch signal, thereby detecting the presence or absence of an object.

Product Features

1.Wide detection range, capable of identifying metals, plastics, glass, paper, liquids, and almost all other materials.
2.Non-contact triggering, no mechanical wear, long service life, suitable for high-frequency work scenarios.
3.Fast response speed, can quickly capture the approach or departure of target objects, compatible with high-speed moving equipment.
4.Detection is unaffected by the color or surface roughness of the target object, offering strong stability.
5.Some models feature waterproof, dustproof, and anti-interference designs, suitable for use in harsh environments such as humidity, dust, and electromagnetic interference.

Product detail

Technical Specifications

Installation method				Shielded	Unshielded
model	DC type	NPN	NO	LJC18A3-5-Z/BX	LJC18A3-B-Z/BX
			NC	LJC18A3-5-Z/AX	LJC18A3-B-Z/AX
			NO+NC
		PNP	NO	LJC18A3-5-Z/BY	LJC18A3-B-Z/BY
			NC	LJC18A3-5-Z/AY	LJC18A3-B-Z/AY
			NO+NC
		Two-wire	NO
			NC
	AC type	Two-wire	NO	LJC18A3-5-J/EZ	LJC18A3-B-J/EZ
			NC	LJC18A3-5-J/DZ	LJC18A3-B-J/DZ
		Three-wire	NO+NC
Detection distance				5mm ± 10%	10mm ± 10%
Set distance				0-4mm	0-8mm
Lag distance				Less than 10% of the detection distance
Detecting objects				Any dielectric substance
Standard inspection object				Iron SPCC 50501mm
Response frequency				DC:0.5kHz AC:25Hz
voltage				DC type: DC12-24V (6-36V) pulsation (P-P) 10% or less AC type: AC110-220V (36-250V) 50/60Hz
Withstand voltage				AC1000V 50/60Hz 1min between the charging part and the outer casing
Voltage effect				Rated power supply voltage range within ±15%, rated power supply voltage value within ±10% detection distance
Current consumption				N.P type: 13mA or less, D type: 0.8mA or less, A type: 1.7mA or less
Control output				N.P type: 300 mA or less, D type: 200 mA or less, A type: 400 mA or less
Loop protection				N.P.D type: reverse connection protection, surge absorption, load short circuit protection, type A: surge absorption
Ambient temperature and humidity				When protecting during operation: each -30-+65°C (no ice, no frost), during operation, protection: 35-95% RH
Temperature effect				Temperature range -30-+65°C, +23°C, ±15% detection distance Temperature range -25 - +60 ° C, +23 ° C, ± 10% detection distance
Insulation resistance				50MΩ or more (DC500 megohmmeter) between the charging part and the outer casing
Material				Housing: Brass nickel plated Detection surface: ABS
Protection level				IP65 (IEC specification)