Reference conditions and procedures for testing industrial and process measurement transmitters—Part 3: Specific procedures for temperature transmitters
GB/T 42567.3-2023 Reference conditions and procedures for testing industrial and process measurement transmitters - Part 3 : Specific procedures for temperature transmitters
1 Scope
This document establishes specific procedures for testing temperature transmitters used in measuring and control systems for industrial process and for machinery control systems.
When the sensing elements (RTD, TC, etc.) in the process measurement transmitter are separated from the temperature transmitter, this document is only applicable to the temperature transmitter without sensing elements. When the sensing elements feature the temperature transmitter separated integrated with the temperature transmitter, this standard applies to the complete device.
For general test procedures, reference is made to IEC 62828-1, which is applicable to all types of industrial and process measurement transmitters (PMT).
Note: In the industrial and process applications, to indicate the process measurement transmitters, it is common also to use the terms "industrial transmitters", or "process transmitters"
The sensing element itself (e.g., RTD, TC, etc.) as well as radiation thermometers are excluded from the scope of this document.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 42567.1-2023 Reference conditions and procedures for testing industrial and process measurement transmitters - Part 1 : General procedures for all types of transmitters (IEC 62828-1:2017, IDT)
IEC 62828-1:2017 Reference conditions and procedures for testing industrial and process measurement transmitters - Part 1 : General procedures for all types of transmitters
3 Terms and definitions
3.1 Definitions regarding temperature
For the purposes of this document, the terms and definitions given in IEC 62828-1 and the following apply
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
- ISO Online browsing platform: available at https://www.iso.org/obp
- IEC Electropedia : available at http://www.electropedia.org/
3.1.1
cold junction compensation; CJC
suitable automatic system to compensate the thermocouple EMF to 0℃
3.1.2
International Temperature Scale of 1990; ITS 90
temperature scale adopted by the International Committee on Weights and Measures (CIPM) in 1989 for the purpose of practical measurements
Note 1: The quantities corresponding to thermodynamic temperature and Celsius temperature defined by this scale are denoted T90 and t90, respectively, where t90 =T90 -T0, with T0 = 273.15 K.
Note 2: The units for T90 and t90 are the kelvin, symbol K, and the degree Celsius, symbol ℃
[Source: GB/T 2900.93-2015, 113-04-18]
3.1.3
resistance temperature detector; RTD
temperature sensor containing a sensing element made of platinum or other metals whose resistance changes with temperature
Note 1: Resistance thermometers are often called RTDs.
Note 2: A platinum resistance thermometer (PRT) is an RTD that has a sensing element made of platinum; other common RTDs are nickel resistance thermometers (NRT) and copper resistance thermometers (CRT), with the sensing element made of nickel or copper respectively.
[Source: IEC 62465:2010, 3.20, modified - Note is added]
3.1.4
thermocouple; TC
pair of conductors of dissimilar materials joined at one end and forming part of an arrangement using the thermoelectric effect for temperature measurement
Note: The production of an electromotive force (EMF) due to a temperature gradient along a conductor
[Source: GB/T 16839.1-2018, 2.3, modified - The abbreviation and note have been added]
4 General description of the device
The general description outlined in Clause 4 and Annex A of GB/T 42567.1-2023 is applicable.
In Annex A of this document, some additional information is only given regarding the measuring section of a temperature industrial and process measurement transmitter
5 Reference test conditions
To verify the influence of external quantities on accuracy, as well as the mechanical and electrical conditions which a device can withstand and still work within specification, the corresponding clause of IEC 62828-1 applies, both for standard reference test conditions and for operating reference test conditions.
6 Test procedures
6.1 General
Clause 6 of GB/T 42567.1-2023 applies, with the following additional requirements.
The general schematic test set-up for a typical temperature PMT is reported in Figure 1.
Note 1: Annex A provides information on the several typologies of typical temperature transmitters
Note 2: The test source generator for RTD is a decade resistance standard or a multifunction temperature calibrator.
Note 3: The test source generator for TC is a voltage generator or a multifunction temperature calibrator.
Note 4: To compensate the TC signal for the reference temperature of 0 ℃, Cold Junction Compensation CJC may be used for TC transmitters.
Note 5: In case of temperature sensing element fully integrated into the temperature PMT, a reference temperature is used.
Note 6: The optional digital output signal is provided for smart and intelligent transmitters and is detected by handheld or PC communicator (configurator).
Figure 2 shows an example of terminal connections for a generic temperature PMT. In this figure, the supply and the output terminals (+, -) are on the upper side, and the input connections to the RTD or TC sensors (1, 2, 3, 4) are on the lower side.
For testing, the RTD and TC shall be replaced by the relevant test source generator.
Note 7: The RTD can be simulated as a two, three or four-wire connection. For platinum RTD, more details are given in IEC 60751.
Note 8: The TC is simulated using specific extension or compensating cables. More details are given in IEC 60584-1 and IEC 60584-3.
For specifications and tolerances of temperature sensors used with temperature PMTs, see:
IEC 60584 and IEC 62460 for TC sensors;
IEC 60751 for RTD sensors.
6.2 Tests at standard and operating reference test conditions
6.2.1 General
For the majority of the tests, the corresponding clause of GB/T 42567.1-2023 applies, in particular see:
Annex B in GB/T 42567.1-2023 for the summary of the tests at standard reference conditions;
Annex C in GB/T 42567.1-2023 for the summary of the tests at operating reference conditions.
The tests are conducted on a test set-up similar to the one shown schematically in Figure 1.
The test source generator (in case of sensing element not integrated into the temperature PMT) or the reference temperature (in case of sensing element fully integrated into the temperature PMT) needed to stimulate the response of the device under test shall have characteristics and performances suitable to the tests required.
In addition to the error due to the sensing element, the process measurement transmitter shall not introduce an additional error greater than 50 % of the error relevant to the pertinent tolerance class of the sensing element.
The following specific tests for temperature transmitters shall be performed in addition.
