GB/T 16855.1-2018Safety of machinery -- Safety-related parts of control systems -- Part 1: General principles for design (English PDF)

Foreword

GB/T 16855 Safety of Machinery - Safety-Related Parts of Control Systems consists

of the following two parts.

--- Part 1.General Principles for Design.

--- Part 2.Validation.

This Part is Part 1 of GB/T 16855.

This Part was drafted as per the rules specified in GB/T 1.1-2009.

This Part replaced GB/T 16855.1-2008 Safety of Machinery - Safety-Related Parts of

Control Systems - Part 1.General Principles for Design. Compared with GB/T 16855.1-

2008, this Part has the major technical changes besides the editorial modifications as

follows.

--- Modify the standard name into Safety of Machinery - Safety-Related Parts of

Control Systems - Part 1.General Principles for Design;

--- Delete the Table 1 in the Introduction (see Introduction of 2008 Edition);

--- Modify the term "system failure" into "systematic failure" (see 3.1.7 of this Edition;

1 Scope

This Part of GB/T 16855 provides safety requirements and guidance on the principles

for the design and integration of safety-related parts of control systems (SRP/CS),

including the design of software. For these parts of SRP/CS, it specifies characteristics

that include the performance level required for carrying out safety functions.

2 Normative References

The following documents are essential to the application of this document. For the

dated documents, only the versions with the dates indicated are applicable to this

document; for the undated documents, only the latest version (including all the

amendments) are applicable to this document.

GB/T 2900.13-2008 Electrotechnical Terminology - Dependability and Quality of

Service [IEC 60050(191).1990, IDT]

3 Terms, Definitions, Symbols and Abbreviated Terms

State of an item characterized by the inability to perform a required function, excluding

the inability during preventive maintenance or other planned actions, or due to lack of

external resources.

Use of a machine in a way not intended by the designer, but which may result from

readily predictable human behavior.

4 Design Considerations

The purpose in following the overall design procedure for the machine is to achieve

the safety objectives (see 4.1). The design of the SRP/CS to provide the required risk

reduction is an integral subset of the overall design procedure for the machine.

5 Safety Functions

Where necessary, the requirements for characteristics and safety functions shall be

adapted for use with different energy sources.

The structure of an SRP/CS is a key characteristic having great influence on the PL.

Even if the variety of possible structures is high, the basic concepts are often similar.

Thus, most structures which are present in the machinery field can be mapped to one

of the categories.

7 Fault Consideration, Fault Exclusion

It is not always possible to evaluate SRP/CS without assuming that certain faults can

be excluded. For detailed information on fault exclusions, see GB/T 16855.2.

8 Validation

The design of the SRP/CS shall be validated (see Figure 3). The validation shall

demonstrate that the combination of SRP/CS providing each safety function meets all

relevant requirements of this Part.

9 Maintenance

Preventive or corrective maintenance can be necessary to maintain the specified

performance of the safety-related parts. Deviations with time from the specified

performance can lead to a deterioration in safety or even to a hazardous situation.

......