Precision sensors,
built to your spec
in Changzhou.

PTC is a binary thermal switch — it trips when the winding reaches its rated T_k and fails safely (an open lead reads as “hot”). Standardised to DIN VDE V 0898-1-401 (formerly DIN 44081/44082) and read by every relay on the market. RTD gives continuous temperature monitoring, useful for alarming, derating and life-prediction. NTC is rarely used in motor windings — the operating range overlaps poorly and the sensitivity advantage is wasted. Most modern motors carry both a PTC chain for trip-level protection and embedded RTDs for continuous monitoring. See our DIN 44081/44082 explainer.

Class F insulation has a 155 °C hot-spot limit. Set the PTC T_k 10-15 °C below that — typically 140-150 °C. If the motor is rated F/B (Class F insulation, Class B rise — the dominant convention in premium-efficiency industrial motors), 140 °C is the conservative pick because it protects the B-rise margin that doubles insulation service life. See our insulation-class article.

For 99 % of process-industry, HVAC and motor-monitoring applications, 3-wire is the right answer. The lead-resistance cancellation is sufficient for Class B accuracy on cable runs up to ~30 m. 4-wire is mandatory when you need Class AA accuracy (calibration laboratory work), when the cable run is > 30 m, or when the cable connectors degrade over time. Our P3L variant of the JSF-M222A is 4-wire silver-shielded for these cases. See our 2/3/4-wire RTD article.

The major R₂₅ values seen in field thermostats are 10 kΩ, 12 kΩ, 15 kΩ and 100 kΩ at 25 °C, with B-values from 3380 K to 3960 K. PT1000 (linear, no B-value) is also widely used in European commercial and smart-home systems. The exact R₂₅ / B-value pair is fixed by the thermostat’s firmware and varies by brand and model. Get this wrong and the sensor still “works” — it just reads the wrong temperature, sometimes by several degrees. Send us the thermostat model number and we will confirm the matching stock part. See our floor sensor article.

The Beta (B-value) equation uses one constant to approximate the NTC’s R(T) curve — cheap to compute, accurate within ±0.3 °C across a 50 °C window. The Steinhart-Hart equation uses three coefficients (A, B, C) and is accurate to ±0.01 °C across the full operating range. For HVAC, appliances and battery thermistors the B-value is sufficient; for medical, calibration and precision instrumentation use Steinhart-Hart. We supply per-lot Steinhart-Hart coefficients on request. See our B-value vs Steinhart-Hart article.

Yes. The original Philips/NXP KTY81, KTY83 and KTY84 family went end-of-life some years ago. We manufacture pin-, package- and curve-compatible parts across all standard tolerance grades (KTY81-110, -120, -121, -122, -150; KTY83-110 through -150; KTY84-130 through -152). Drop-in for legacy designs, optional reel packaging and lead-bend forming for new production lines. See our KTY explainer.

Yes — engineering samples ship internationally free of charge for qualified projects. Standard ground or express shipping is included to most regions. For remote destinations or expedited courier, a freight charge may apply — we will confirm before dispatch. Standard sample dispatch is within 48 hours of order confirmation; custom housing assemblies have a 2-week first-article lead time.

We build to international standards and can arrange the certifications you need per OEM order. For market-specific certifications (UL, VDE, CQC, TÜV, CE, CB and others), we manufacture the parts to the relevant standard and ship production samples directly to your nominated third-party test house — you receive certification documentation from a body you already trust, against parts built exactly to your spec.