Room Temperature Sensor NTC 20K (Passive)

Passive NTC 20K sensor for measuring indoor air temperature. Connects directly to the NTC 20K inputs of DDC, PLC, fan-coil and VRF controllers and mounts on the wall or on a flush-mounting box. KEY FEATURES • TDK (EPCOS) NTC 20 kΩ element, R25 tolerance ±1 % (≈ ±0.2 K at 25 °C) • Screwless push-in terminal, 0.2 … 1.5 mm² — fast and reliable wiring • Ventilation slots on all four sides, rear cable entry • Clean 80 × 80 × 21 mm ABS housing; wall or flush-box mounting • Passive, 2-wire, non-polarised: no power supply needed 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 Measuring range: 0 … +50 °C (room) 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 Terminal: 2-pole push-in, 5.08 mm, PA66 UL 94 V-0 Wire size / strip length: 0.2 … 1.5 mm² (AWG 22 … 16) / 9 mm Withstand voltage (terminal): AC 2500 V / 1 min Housing: ABS, UL 94 HB; heat deflection (HDT) 85 °C Dimensions (W × H × D): 80 × 80 × 21 mm Mounting: Wall (4 screws) or flush-mounting box Cable entry: From the rear of the base Weight: 34.65 g Operating environment: 0 … +50 °C, dry indoor, non-condensing Degree of protection: IP30 (EN 60529) Pollution degree / overvoltage category: 2 / III Terminal approvals: UL (cURus), VDE, CQC · RoHS compliant 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 · 20 °C: 25,366 Ω · 25 °C: 20,000 Ω · 30 °C: 15,884 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. • Separate the cover from the base and feed the cable through the rear entry; mount the base flat on the wall or a flush box with 4 screws. • Seal the cable entry and the conduit opening; air coming from inside the wall falsifies the reading. • Strip the wires 9 mm and push them into terminals 1–2 (use ferrules on stranded wire), then fit the cover. • Mount about 1.5 m above the floor on an inner wall; avoid direct sun, radiators, air outlets, door/window areas and outside walls. • 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