GB/T 34035-2017Field test methods for thermocouples (English PDF)

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

Introduction

Thermocouples are widely used in industry and have high reliability when used within their specified temperature range. However, if in use out Now failure, the consequences can be light and heavy, and even threaten personal safety. In general, this may result in significant loss of equipment, product, or uptime. use The user should weigh the potential consequences of a thermocouple failure to determine which tests to make before and after thermocouple installation and during use.

This standard is intended for the thermocouple, thermocouple machine and the connecting wire guide to provide field testing to avoid the thermocouple in the storage, installation or Damage during use, not as a guide to acceptance testing.

The test method covers basic tests to ensure correct installation of the thermocouple, as well as some simple tests necessary for failure analysis. and Uniformity, capacitance and loop current step response thermocouple test, due to the need to be equipped with complex equipment and for complex analysis, in this standard No rules.

Normally produced thermocouple malfunctions, usually due to incorrect installation and operation outside the specified limits during use. These ones Most of the most common forms of fault conditions can be detected by using the test methods given in this standard.

When the thermocouple machine for the first time installed in the working environment should be the provisions of this standard test. However, these tests do not guarantee the thermocouple Function to accurately display the temperature. To ensure accuracy, the need to select the appropriate thermocouple and instrumentation, as well as measuring the temperature to select the appropriate test Points.

1 Scope

This standard specifies the method of testing the thermocouple machine, including the compensation wire, before and after installation, or after a period of use.

The purpose of the test is to ensure that the thermocouple machine is not damaged during storage or installation, compensating for the positive polarity of the connection between the conductor and the terminal Indeed, and for the future test evaluation thermocouple machine is damaged after use to provide reference data. Some of these tests may not apply to highs Specific types of thermocouples operating at the recommended limits of temperature.

This standard specifies the test, including the installation of thermocouple after measuring the following variables, and to determine whether the thermocouple machine is working In the damage to provide reference data.

--- Loop resistance.

- hot electrode;

- Compensation wire and thermode.

--- Insulation resistance.

- thermocouple machine insulation;

- thermocouple machine and compensation wire insulation.

--- Thermoelectric power.

- hot electrode;

- Compensation wire and thermocouple machine.

2 Normative references

The following documents for the application of this document is essential. For dated references, only the dated version applies to this document. For undated references, the latest edition (including all amendments) applies to this document.

GB/T 4989-2013 Compensating lead for thermocouple

GB/T 25475-2010 Industrial automation instruments terminology temperature instruments

Industrial thermocouples

3 Terms and definitions

GB/T 25475-2010 defined and the following terms and definitions apply to this document.