TSM designations define the sensor resistance at 0 °C and its resistance ratio at 100 °C. They determine the measurement characteristic that the receiving instrument must use; the evidence does not establish that 50M W100 1.426, 50M W100 1.428, or 53M W100 1.426 is inherently more reliable.
Decode 50M, 53M, and W100
A 50M copper sensing element has 50 Ω resistance at 0 °C, while a 53M element has 53 Ω at 0 °C. W100 is the ratio of resistance at 100 °C to resistance at 0 °C:
W100 = R100 / R0
R100 = W100 × R0| Characteristic | R0 | Calculated R100 |
|---|---|---|
| 50M, W100 1.426 | 50 Ω | 71.30 Ω |
| 50M, W100 1.428 | 50 Ω | 71.40 Ω |
| 53M, W100 1.426 | 53 Ω | 75.578 Ω |
The two 50M characteristics therefore differ by 0.10 Ω at 100 °C. A receiving instrument must apply the matching calibration table or configured input characteristic to translate resistance into temperature.
Why W100 Differs Between Sensors
W100 reflects the temperature coefficient of the copper used in the sensing element. The evidence attributes variation to material purity and wire-lot variation. Production measures W100 for each sensor and records the resulting value in its passport. The cited production limits are 1.424 through 1.428 under an unspecified GOST document and manufacturer technical specifications; verify the applicable documents rather than assuming a particular standard edition.
A value of 1.428 is not evidence by itself of greater mechanical reliability, thicker wire, or a superior finished sensor. The reported standard copper elements use practically identical construction, so assess reliability from the complete assembly and its documented specifications rather than W100 alone.
Wire and Element Construction
A 0.05 mm wire is used for 10 mm sensing elements in sensors whose working section is up to 100 mm; a 0.063 mm wire is used for 30 mm sensing elements in the remaining designs. These dimensions describe reported construction choices and are not tied specifically to W100 1.426 versus 1.428.
The wire is wound into a coil and the coil resistance is measured. The evidence does not provide a verified cut length, turn count, winding tension, insulation build, or final calibration procedure for either wire diameter. Do not derive an exact production length from resistance alone without the wire lot's measured resistance per unit length and the complete element geometry.
Select and Verify the Sensor
- Read the sensor passport and identify both its 0 °C designation—50M or 53M—and its measured W100 value.
- Confirm that the receiving instrument explicitly supports that complete characteristic. Evidence indicates that at least some instruments support the older 53M characteristic, but support cannot be assumed for every instrument.
- Configure the matching calibration characteristic, then verify the measurement with known resistance or controlled temperature points appropriate to the required range.
- If reliability is the deciding factor, compare the complete manufacturers' construction and ratings; do not rank sensors using W100 or wire diameter alone.
FAQ
What is the difference between TSM 50M W100 1.426 and 1.428?
Both measure 50 Ω at 0 °C, but their calculated resistances at 100 °C are 71.30 Ω and 71.40 Ω. Configure the receiving instrument for the sensor's documented characteristic.
Is a TSM sensor with W100 1.428 more reliable?
The evidence shows no reliability advantage for 1.428. W100 primarily reflects the copper element's temperature coefficient and does not prove better mechanical construction.
Can a 53M sensor replace a 50M sensor?
Not without explicit instrument support: 53M measures 53 Ω at 0 °C instead of 50 Ω and requires its matching calibration characteristic. Check the instrument configuration and documentation before substitution.
