Omega Products 55004 User Manual

High Temperature Thermistors

Glass Encapsulated, Up to 200°C (392°F)

55000 Series

U Maximum Continuous Use, 200°C

(392°F) [Short Term Use to 250°C (482°F)]

U Excellent Long Term Stability U Hermetically Sealed Glass Bead U Available in 2252, 3000, 5000 and

10,000 Ω Resistances at 25°C (77°F)

U Tolerance: ±0.2°C From 0 to 70°C

(32 to 158°F)

U 2.4 mm (0.095") Max Diameter Bead U #

32 AWG, Gold Plated Dumet

63.5 mm (2.5") L

The OMEGA® 55000 Series glass encapsulated thermistors provide a higher temperature alternative to the OMEGA 44000 Series epoxy coated thermistors where needed. With a maximum continuous temperature rating of -80 to 200°C (-112 to 392°F), and intermittent operation to 250°C (482°F), the 55000 can be used in those applications previously out of reach.

With the same small size as our 44000 thermistor Series, and solderable #32 AWG gold plated Dumet leads, the 55000 thermistor can be used interchangeably wherever our 44000 Series thermistors are used.

Table 1: Steinhart-Hart Constants Model

No. R25°C A B C 55004 2252 Ω 1.4705 x 10-3 2.3780 x 10-4 1.0389 x 10 55005 3000 Ω 1.4052 x 10-3 2.3692 x 10-4 1.0125 x 10 55007 5000 Ω 1.2870 x 10-3 2.3585 x 10-4 9.4346 x 10 55016 10,000 Ω 1.1275 x 10-3 2.3441 x 10-4 8.6482 x 10

Leads

Thermistor bead shown actual size.

#32 AWG gold plated dumet wire leads 63.5 (2.5) L.

2.4 (0.095) diameter bead.

Resistance Vs. Temperature Characteristics

The Steinhart-Hart Equation has become the generally accepted method for specifying the resistance vs. temperature relationship for thermistors. The Steinhart-Hart equation for temperature as a function of resistance is as follows:

⁄T = A + B [Ln(R)] + C [Ln(R)]

where: A, B and C are constants derived from three temperature test points.

R = Thermistors resistance in Ω T = Temperature in Kelvins K (°C + 273.15)

To determine the thermistor resistance at a specific temperature point, the following equation is used:

(beta-(alpha/2))1/3 – ((beta+(alpha/2))1/3

R = e

where: alpha = ((A-(1/T))/C)

beta =

The A, B and C constants for each of our thermistor

-7

selections can be found in Table 1. Using these

-7

constants with the above equations, you can determine the temperature of the thermistor based on

-8

its

-8

particular temperature.

SQRT(((B/(3C))3)+(alpha2/4))

resistance, or determine a thermistors resistance at a

63.5 (2.5)

Dimension: mm (inch)

D-11

Stability and Drift

Thermistors are generally very accurate and stable devices, but conditions such as over-temperature exposure, thermal or mechanical shock, or subjecting them to over-current conditions can result in a change in resistance. The 55000 Series thermistors are chemically stable and not significantly affected by aging. The following shows typical stability data for the 55016 thermistor:

Typical Thermometric Drift (±0.2°C Elements)

Operating Temp 10 Months

0°C <0.01°C 25°C <0.01°C 100°C 0.12°C 150°C 0.15°C 200°C 0.20°C

Tolerance Curves

Accuracy tolerances for thermistor sensors are expressed as a percentage of temperature. This is also referred to as

interchangeability.

The 55000 Series thermistors have a tolerance of 0.2°C between 0 and 70°C.

Operating Current and Dissipation Constant

The suggested operating current for bead-style thermistors is approximately 10 to 15 micro-amps. thermistors can experience self-heating effects if they are exposed to operating currents that are high enough to create more heat than the thermistor can dissipate to its surroundings. The 55000 Series thermistors have a dissipation constant of 1.5 milliwatts/°C in air.

Time Constant

The time constant is the time required for a thermistor to react to a step change in temperature. For example, if exposed to a change from 0 to 100°C (32 to 212°F), the 63% time constant would be the time required for the thermistor to indicate a resistance to its value at 63°C (145°F). The time constant for the 55000 Series thermistor is less than 15 seconds in air.

Table 2: Interchangeability Tolerances

Temp Model No. 55004, ±0.20°C (°C) ±°C ±Ω

-80 1.00 142,000

Shown actual size.

-40 0.40 2018 0 0.20 75 40 0.20 10 70 0.20 2.7 100 0.30 1.3 150 1.00 0.9

Note: Temperature values (°C) are the same for each tolerance group (±0.10 or ±0.20), resistance tolerances will change based on resistance at 25°C (77°F).

Discount Schedule

4 to 10 ................................................................. 9%

11 to 24 ............................................................. 12%

25 to 49 ............................................................. 18%

50 to 99 ............................................................. 20%

100 and over ..................................................... 25%

To Order Visit omega.com/55000 for Pricing and Details Beta Ratio Best

Model Resistance Tolerance 0 to 50°C Ω Working Short Term Number at 25°C (0 to 70°C) (K) 25/125°C Temperature Temperature

55004 2252 0.2°C 3891 29.26

(-112 to 392)

55005 3000 0.2°C 3891 29.26

(-112 to 392)

55007 5000 0.2°C 3891 29.26

(-112 to 392)

55016 10000 0.2°C 3891 29.26

(-112 to 392)

Ordering Example: 55007, thermistor, 5000 Ω at 25°C (77°F), 2.4 mm (0.095") maximum bead diameter with two 63.5 mm (2.5") L gold plated dumet lead wires.

-80 to 200°C

250°C (482°F)

D-12