| Technical Data > Manufacturing Tolerances |
| R/T Curve Characteristics and Manufacturing Tolerances Tables | ||||||||
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These tables list in 5 °C increments the resistance ratios, NTC’s, point match resistance tolerances, and interchangeable temperature tolerances for Cornerstone Sensors’ R/T curves. These parameters are defined as follows:
RESISTANCE RATIO - The Rt/R25 ratio is the ratio of the resistance at temperature “t” to the resistance at 25 °C. To calculate the resistance of a thermistor at a temperature point other than 25 °C, multiply the given resistance ratio by the resistance at 25 °C. NTC - The Negative Temperature Coefficient of resistance is the % change in resistance per change in temperature, expressed in units of -%/ °C. To determine the approximate % resistance tolerance of a thermistor at a particular temperature, multiply the given NTC value by the temperature tolerance at that temperature. POINT MATCHED - For thermistors with a specified tolerance at a single temperature point, the manufacturing tolerance is used to determine the tolerance at other temperature points. Typically, thermistors are specified at 25 °C. To determine the resistance tolerance at another temperature point, add the manufacturing tolerance to the specified point matched tolerance. For example, a Curve D thermistor with a ±10 % resistance tolerance at 25 °C has a ±11.4 % tolerance at 0 °C. Point matched thermistors should typically not cycle or operate continuously above 105 °C. INTERCHANGEABLE .CA Suffix - An interchangeable tolerance means that a thermistor has a temperature tolerance specified over a temperature range. For example, a “.CA” suffix indicates a ± 0.2 °C temperature tolerance from 0 °C to 70 °C. Typically, interchangeable thermistors should not cycle or operate continuously above their specified temperature range.
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