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 Series thermistors can be used in those applications previously
out of reach.
With the same small size as our 44000 Series thermistor, and with solderable #32 AWG gold plated Dumet
leads, the 55000 Series thermistor can be used
interchangeably wherever our 44000 Series
thermistors are used.
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:
1⁄T = A + B [Ln(R)] + C [Ln(R)]3
where: A, B and C are constants derived from three
temperature test points.
R = Thermistor resistance in Ω
T = Temperature in Kelvins K (°C + 275.15)
To determine the thermistor resistance at a specific
temperature point, the following equation is used:
R = e(beta-(alpha/2))1/3-((beta+(alpha/2))1/3
where:
alpha = ((A-(1/T))/C)
Model Number
R25°C
A
B
C
55004
2252Ω
1.4705x10-3
2.3780x10-4
1.0389x10-7
55005
3000Ω
1.4052x10-3
2.3692x10-4
1.0125x10-7
55007
5000Ω
1.2870x10-3
2.3585x10-4
9.4346x10-8
55016
10000Ω
1.1275x10-3
2.3441x10-4
8.6482x10-8
beta = SQRT(((B/(3C))3)+(alpha2/4))
The A, B and C constants for each of our thermistor
selections are shown in the table to the right. Using these
constants, you can
determine the temperature of the thermistor based on
its resistance, or determine a thermistor's resistance at a
particular temperature.
Model No. 55016 Thermistor
Operating Temperature
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
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:
Temp °C
Model No. 55004, ±0.20°C
±°C
±Ω
-80°C
1.00
142,000
-40°C
0.40
2018
0°C
0.20
75
40°C
0.20
10
70°C
0.20
2.7
100°C
0.30
1.3
150°C
1.00
0.9
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 do have a tolerance of ±0.2°C between
0 and 70°C, but can be used across their entire temperature range.
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.
† All dollar amounts on this site are shown in US currency.
Ordering Example: (1) 55007 Thermistor, 5000 ohms at 25°C (77°F), 2.4 mm (0.095") max bead diameter with two 63.5 mm (2.5") Long Gold plated Dumet lead wires., $22.00
