Cable Temperature Sensor NTC 20K (Passive)

Passive NTC 20K cable temperature sensor for measuring liquid and air temperature. It is used as an immersion sensor on pipework with an EPL-SS stainless steel sensor well, or in air ducts with a mounting flange. Connects directly to the NTC 20K inputs of DDC, PLC and fan-coil controllers. KEY FEATURES • TDK (EPCOS) NTC 20 kΩ element, R25 tolerance ±1 % (≈ ±0.2 K at 25 °C) • Ø6 mm stainless steel sleeve, epoxy filled; probe and cable entry IP67 • 1.75 m LIYY 2 × 0.35 mm² cable with ferrule-fitted ends, ready to install • 50 / 100 / 150 mm probe lengths; a direct fit for EPL-SS wells • Passive, 2-wire, non-polarised: no power supply needed PROBE LENGTH OPTIONS • 50 mm — matching well EPL-SS-50 • 100 mm — matching well EPL-SS-100 • 150 mm — matching well EPL-SS-150 Please state the probe length when ordering. Well and mounting flange are ordered separately. TECHNICAL SPECIFICATIONS Sensing element: NTC thermistor, epoxy-coated disc (TDK EPCOS) Resistance: R25 = 20 kΩ · B25/100 = 4300 K (R/T curve 2904) Tolerance: R25 ±1 % → ≈ ±0.2 K @ 25 °C Operating temperature (probe + cable): −30 … +90 °C (element −55 … +155 °C) Measuring current: ≤ 0.1 mA (recommended) Self-heating: ≈ 4 mW/K (element) → ≈ 0.05 K at 0.1 mA Output: Passive resistance, 2-wire, non-polarised Sleeve: Stainless steel, Ø 6 mm, epoxy filled Probe length: 50 / 100 / 150 mm Cable: LIYY 2 × 0.35 mm², fine-stranded copper, PVC insulated, PVC sheathed Cable outer diameter / length: Ø 4.2 mm / 1750 mm Weight: 48.4 g / 53.5 g / 58.7 g (L = 50 / 100 / 150 mm) Degree of protection: IP67 (probe and cable entry, EN 60529) Protection class: III — safety extra-low voltage (SELV/PELV) circuits only Element approval: UL (E69802) Conformity: CE · WEEE 2012/19/EU (not household waste) RESISTANCE VALUES (EXAMPLES) 0 °C: 71,126 Ω · 25 °C: 20,000 Ω · 50 °C: 6,673 Ω · 80 °C: 2,135 Ω Thanks to the high resistance of NTC 20K, cable resistance has very little effect: even on a 100 m run of 2 × 0.5 mm² the error is only −0.01 K at 25 °C, so no offset correction is normally needed. WIRING AND INSTALLATION • On the controller, set the NTC 20K input to the B25/100 = 4300 K curve. The common "NTC 20K B3950" curve is different; selecting it can shift the reading by 1.5–2 °C. • Pipework (water): Fit an EPL-SS well of the matching length into the line. Apply thermal paste in the well, push the sensor fully home and secure it. • Duct (air): Mount with a mounting flange, perpendicular to the airflow, with the probe tip in the centre of the duct cross-section. • Do not bend the cable sharply right behind the sleeve exit. • If an extension is needed, make the joint in a junction box and use shielded cable for long runs. Do not immerse directly in a pressurised medium without a well. • Connect the sensor only to the low-voltage sensor input of a controller; never connect it to 230 V mains. Wiring must be done by qualified personnel with the power off; do not run the sensor cable in the same duct or conduit as 230 V power cables. SCOPE OF DELIVERY 1 × sensor (well and mounting flange sold separately)