What is a Pt100 probe?
A Pt100 probe is an assembly composed of an RTD element, a sheath, a lead wire, and a termination or connection. The Pt100 is a temperature sensor that contain a resistor that changes resistance value as its temperature changes.
Pt100 probes may be terminated in a connection head, quick disconnect, terminal block, or extension wire. OMEGA’s standard terminations are pictured on product pages. Other termination styles are available upon special request. For something other than standard products, please contact our sales team to submit a full description and/or sketch of your desired version.
The Lead Wire
Lead styles and RTD extension cables are offered in one of four configurations. Style 2 is OMEGA’s standard. Be sure to select the configuration that is compatible with your instrumentation.
The sheath, a closed end tube, immobilizes the element, protecting it against moisture and the environment to be measured. The sheath also provides protection and stability to the transition lead wires from the fragile element wires. OMEGA’s standard sheaths are 3 mm (1/8") and 6 mm (1/4") O. D. 304 stainless steel tubes. Other O.D.’s and materials are available upon request.
The standard OMEGA® RTD probe is made with a 100 ohm platinum European curve element (á = 0.00385).
OMEGA’s "PR" style RTD probe assemblies are rated for use in temperatures up to 600°C (1110°F). The "PRTF" style probes are rated up to 260 or 500ºC depending on construction Temperature limitations may be placed on termination styles due to the wire insulation used. The maximum temperature rating available on special order is 750°C (1380°F). If probe is intended for high temperature use, please request a quotation.
OMEGA stocks a broad line of Pt100 probes for immediate delivery. Many special assembly probes are available for shipment within two weeks of receipt of your order. Please consult Sales Department for further details on your special needs.
Definition of RTD Probe Part Number
Type: Select style PR- or PRTF-10, -11, -12, -13, -14, -15, -16, -17, -18, -19.
Lead Configuration: Specify 1, 2, 3, or 4. Style 2 is standard.
Resistance: 100 ohms is standard. 50, 200, 500, 1000, or 2000 ohms are available, usually with two-week delivery.
Sheath Diameter: 1.5 mm (1/16"), 3 mm (1/8"), 4.5 mm (3/16"), 6.0 mm (1/4"), and 8.0 mm (5/16") are available. 3 mm (1/8") and 6 mm (1/4") O.D. probes are stocked for off-the-shelf delivery.
Sheath Length: There is no upper limit on sheath length. The minimum practical length is 2 inches.
Curve: European (E): α = 0.00385 ohms/ohm/°C, American
(A): α = 0.00392 ohms/ohm/°C
Lead Configurations of Pt100 Probes
Lead configuration 1 provides one connection to each end of the sensor. This construction is suitable where the resistance of the run of lead wire may be considered as an additive constant in the circuit, and particularly where the changes in lead resistance due to ambient temperature changes can be ignored.
Note: The resistance of probe and extension is added to the sensor resistance and will increase the measured value.
Lead configuration 2 (Standard) provides one connection to one end and two to the other end of the sensor. Connected to an instrument designed to accept three-wire input, compensation is achieved for lead resistance and temperature change in lead resistance. This is the most commonly used configuration.
Lead configuration 3 provides two connections to each end of the sensor. This construction is used for measurements of the highest precision.
Lead configuration 4 is similar to Lead Configuration 3 except that a separate pair of wires is provided as a loop to provide compensation for lead resistance and ambient temperature changes in lead resistance.
In this article, the different options to wire an RTD Pt100 probe are explained.