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GB/T 9224-2025DC periodmeters (English PDF)

直流周期计

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

August 1, 2025

Implementation date

February 1, 2026

Scope

GB/T 9224-2025 is the English-translated version of 直流周期计.

GB/T 9224-2025 is the Chinese product standard for the DC periodmeters used to measure reactor period in nuclear reactor instrumentation.

Clause 1 lists what it covers - technical requirements, inspection rules, marking, packaging, transportation and storage, and the matching test methods - and says it applies to the manufacture, inspection and sale of these instruments.

Its contents list breaks the technical requirements into appearance and mechanical characteristics, measuring range, measurement error, response time, the swing of the zero point corresponding to an infinite period, environmental adaptability, stability, electrical safety and electromagnetic compatibility, with a separate clause for the test methods.

Instrument makers and reactor operators use it as the acceptance basis for these meters. It replaces GB/T 9224-1998, was issued on 1 August 2025 and applies from 1 February 2026.

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Document preview — GB/T 9224-2025

National Standard of the People's Republic of China

ICS: 27.120.20
Classification: F 82
Replacing: GB/T 9224-1998

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

Preface
1 Scope
2 Normative references
3 Terms and Definitions
4 Technical Requirements
4.1 Appearance and mechanical characteristics
4.2 Measuring range
4.3 Measurement Error
4.4 Response Time
4.5 "Zero Point" (Corresponding to Period infinity) Swing
4.6 Environmental Adaptability
4.7 Stability
4.8 Electrical Safety
4.9 Electromagnetic Compatibility
5 Test Method
5.1 General provisions of the test
5.2 Appearance and mechanical properties
5.3 Measuring range and measurement error
5.4 Response Time
5.5 "Zero Point" (Corresponding to Period infinity) Swing
5.6 Environmental adaptability
5.7 Stability
5.8 Electrical Safety
5.9 Electromagnetic Compatibility
6 Inspection Rules
6.1 Factory Inspection
6.2 Type inspection
7 Marking, packaging, transportation, storage
7.1 Signs
7.2 Packaging
7.3 Transportation and storage
References

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting.

This document replaces GB/T 9224-1998 "DC periodometer". Compared with GB/T 9224-1998, except for structural adjustments and editorial changes, In addition to the dynamic, the main technical changes are as follows.

--- Added the terms and definitions of full-scale value (see 3.3);

--- Changed the measuring range (see 4.2, 4.3.1 of the 1998 edition);

--- Changed the description of the error (see 4.3, 4.3.2 of the 1998 edition);

--- Deleted the adaptability requirements for power supply changes (see 4.4.4 and 4.4.5 of the 1998 edition);

--- Changed the range of relative humidity (see 4.6.1, 5.5.3 of the 1998 edition);

--- Deleted the extreme operating temperature requirements (see 4.1, 4.4.1.2, 4.4.2.2, 5.5.1.2, 5.5.2.2 of the 1998 edition);

--- Added transportation requirements (see 4.6.2, 5.6.2);

--- Changed the stability requirements (see 4.7, 4.5 of the 1998 edition);

--- Changed the electrical safety requirements (see 4.8, 4.6 of the 1998 edition);

--- Deleted the packaging technical requirements (see 4.8 of the 1998 edition);

--- Added standard test conditions (see 5.1.1);

--- Changed the measurement error test method (see 5.3, 5.4.1 of the 1998 edition);

--- Changed the environmental adaptability test method (see 5.6, 5.5 of the 1998 edition);

--- Changed the stability test method (see 5.7, 5.6 of the 1998 edition);

--- Changed the electrical safety test method (see 5.8, 5.7 of the 1998 edition);

--- Replaced the industry standard with the normative reference GB/T 191 (see Chapter 7, 4.8 and Chapter 7 of the 1998 edition).

1 Scope

This document specifies the technical requirements, inspection rules, marking, packaging, transportation and storage requirements for DC cycle meters for nuclear reactors. The corresponding test methods.

This document applies to the production, inspection and sales of DC periodometers for nuclear reactor measurements.

2 Normative references

The contents of the following documents constitute the essential clauses of this document through normative references in this document.

For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies to this document.

GB/T 191 Pictorial markings for packaging, storage and transportation

GB/T 2423.56 Environmental testing Part 2: Test methods Test Fh. Broadband random vibration and guidance

GB/T 8993 Environmental conditions and test methods for nuclear instruments

GB/T 11684 Electromagnetic environmental conditions and test methods for nuclear instruments

GB/T 13306 Signage

GB/T 13384 General technical requirements for packaging of electromechanical products

GB/T 19661.1 Safety requirements for nuclear instruments and systems Part 1: General requirements

3 Terms and Definitions

The following terms and definitions apply to this document.

3.1 DC period meter

A device that measures the time constant of an exponentially varying DC current.

Note: The output signal is a voltage signal, proportional to the inverse of the time constant (hereinafter referred to as the period). The proportional relationship is specified by the manufacturer.

3.2 Response time

The time required for the output signal to reach 90% of its final value for the first time after an exponentially changing DC current is input.

3.3 Full scale value

The output voltage signal corresponding to the reciprocal of the absolute value of the shortest period within the measurement range.

4 Technical Requirements

4.1 Appearance and mechanical properties

The exterior and mechanics include the following features.

a) The surface coating of the instrument should be firm and smooth, without defects such as rust, cracks, and peeling;

b) The writing on the nameplate and panel should be clear;

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.

Referenced standards

Normative references

Editions of GB/T 9224

Edition	Title	Revision	Status
GB/T 9224-2025	DC periodmeters	current edition	Current
GB/T 9224-1998	DC periodmeters	previous edition	Superseded

This page sells the current edition, GB/T 9224-2025. Earlier editions are listed for reference only.

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