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AS/NZS 4024.1602:2025
[Current]Safety of machinery, Part 1602: Interlocking devices associated with guards - Principles for design and selection (ISO 14119:2024, IDT)
AS/NZS 4024.1602:2025 specifies principles for the design and selection (independent of the nature of the energy source) of interlocking devices associated with guards and provides guidance on measures to minimize the possibility of defeat of interlocking devices in a reasonably foreseeable manner.
Published: 21/11/2025
Pages: 107
Table of contents
Cited references
Content history
Table of contents
Header
About this publication
Preface
Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols
5 Operating principles and types of interlocking devices associated with guards
5.1 General
5.2 Principles of guard interlocking without guard locking
5.3 Principles of guard interlocking with guard locking
5.3.1 General
5.3.2 Interlocking device with guard locking
5.3.2.1 Interlocking device with guard locking by form
5.3.2.2 Interlocking device with power-operated guard locking by electromagnetic force
6 Requirements for the design and the arrangements of interlocking devices with and without guard locking
6.1 General
6.2 Arrangement and fastening of position switches, bolt locks and access locks
6.3 Arrangement and fastening of actuators
6.3.1 General
6.3.2 Cams
6.4 Actuation modes of interlocking devices
6.5 Mechanical stop
6.6 Additional requirements on guard-locking devices
6.6.1 General
6.6.2 Locking force
6.6.3 Electromechanical guard-locking device
6.6.3.1 General
6.6.3.2 Guard-locking monitoring
6.6.4 Electromagnetic guard-locking device
6.6.4.1 General
6.6.4.2 Guard-locking monitoring
6.6.4.3 Basic measures for minimizing defeat possibilities
6.7 Additional requirements on access locks
6.7.1 General
6.7.2 Locking force
6.8 Whole body access
6.9 Supplementary releases
6.9.1 Escape release of guard locking
6.9.2 Auxiliary release of guard locking
6.9.3 Emergency release of guard locking
6.10 Interlock blocking
7 Selection of an interlocking device
7.1 General
7.2 Selection of a guard-locking device
7.2.1 Overall system response time and access time
7.2.2 Specific requirements for selection of guard-locking devices
7.2.3 Selection of supplementary guard-locking releases
7.3 Environmental conditions considerations
7.3.1 General
7.3.2 Influence of dust on Type 2 and Type 5 interlocking devices
7.4 Considerations for the application of trapped key interlocking systems
8 Design to minimize the motivation to defeat
8.1 System design
8.2 Methodology procedure
8.3 Additional measures to minimize possibility of defeat
8.4 Additional measures to minimize possibility of defeat for Type 5 devices
8.4.1 General
8.4.2 Key retention
8.4.3 Reproduction of keys
9 Requirements for the control system
9.1 General
9.2 Assessment of faults and fault exclusions
9.2.1 Assessment of faults
9.2.2 Fault exclusion
9.2.2.1 General
9.2.2.2 Mechanical fault exclusions for Type 1 interlocking devices
9.2.2.3 Mechanical fault exclusions for Type 2 interlocking devices without guard locking
9.2.2.4 Mechanical fault exclusions for Type 3 and Type 4 interlocking devices without guard locking
9.2.2.5 Mechanical fault exclusions for guard locking
9.2.2.6 Fault exclusions for Type 5 interlocking devices
9.2.3 Examples for measures to prevent common cause failures through direct and non-direct mechanical action of the position switches of Type 1 interlocking devices
9.2.4 Energy source diversity
9.3 Release of guard-locking device
9.4 Series connection of electro-mechanical interlocking devices
9.5 Electrical and environmental conditions
9.5.1 General
9.5.2 Performance considerations
9.5.3 Immunity from disturbance
9.5.4 Electrical operating conditions
9.5.5 Clearances and creepage distances
10 Information for use
10.1 General
10.2 Information for use given by the manufacturer of interlocking devices
10.2.1 Marking
10.2.2 Instructions
10.3 Information for use given by the manufacturer of the machine
Annex A
A.1 Rotary cam
A.1.1 Description
A.1.2 Typical characteristics
A.1.3 Remarks
A.2 Linear cam
A.2.1 Description
A.2.2 Typical characteristics
A.2.3 Remarks
A.3 Hinge
A.3.1 Description
A.3.2 Typical characteristics
A.3.3 Remarks
A.4 Pneumatic/hydraulic interlocking devices
A.4.1 Examples
A.4.2 Remarks
Annex B
B.1 Tongue-actuated position switch
B.1.1 Description
B.1.2 Typical characteristics
B.1.3 Remarks
Annex C
C.1 Proximity position switch
C.1.1 Description
C.1.2 Typical characteristics
C.1.3 Remarks
Annex D
D.1 Coded magnetic operated interlocking device
D.1.1 Description
D.1.2 Typical characteristics
D.1.3 Remarks
D.2 Coded RFID-operated interlocking device
D.2.1 Description
D.2.2 Typical characteristics
D.2.3 Remarks
Annex E
E.1 Example of interlocking device with separate detection of guard position and position of the locking elements
E.1.1 Description
E.1.2 Typical characteristic
E.2 Interlocking function ensured by detecting separately guard position and position of the guard-locking device
E.2.1 Description
E.2.2 Typical characteristics
E.3 Interlocking function ensured by detecting lock position only by detecting the position of the locking device
E.3.1 Description
E.3.2 Typical characteristic
E.4 Interlocking device with electromagnetic guard-locking device
E.4.1 Description
E.4.2 Typical characteristics
E.5 Interlocking device with guard locking, with manually operated delay device
E.5.1 Description
E.5.2 Typical characteristics
E.5.3 Remarks
Annex F
F.1 General
F.2 Example 1 — Category 1
F.2.1 Safety function
F.2.2 Functional description
F.2.3 Design features
F.3 Example 2 — Category 3
F.3.1 Safety functions
F.3.2 Functional description
F.3.3 Design features
F.4 Example 3 — Category 4
F.4.1 Safety function
F.4.2 Functional description
F.4.3 Design features
Annex G
Annex H
Annex I
I.1 Locking force test
I.1.1 General
I.1.2 Evaluation
I.1.2.1 General
I.1.2.2 Requirements on the test device
I.1.2.3 Requirements on the force measurement device
I.2 Impact resistance test
I.2.1 General
I.2.2 Test procedure
I.2.3 Test requirements
Annex J
J.1 General
J.2 Fault masking
J.2.1 Principle
J.2.2 Direct fault masking
J.2.3 Unintended reset of a fault
J.3 Methodology for evaluation of DC for series-connected interlocking devices
J.4 Limitation of DC by effects of series-connected devices
J.4.1 General
J.4.2 Simplified method for the determination of the maximum achievable DC
J.4.3 Regular method for the determination of the maximum achievable DC
J.4.3.1 Estimation of the fault masking probability (FM)
J.4.3.2 Determination of the maximum achievable DC
J.4.4 Interlocking devices with potential free contacts and other potential free contacts of devices with different functionality connected in series
J.5 Avoiding fault masking
J.6 Application examples in an integrated machinery system (IMS)
J.6.1 Application example 1
J.6.2 Application example 2
Annex K
K.1 Operating principles and typical forms of trapped key interlocking system
K.1.1 General
K.1.1.1 Operating sequence
K.1.1.2 Key coding
K.1.2 Functional decomposition of a trapped key interlocking system
K.1.3 Energy control
K.1.3.1 General
K.1.3.2 Energy control through direct mechanical action (power interlocking)
K.1.3.3 Energy control through non-direct mechanical action (control interlocking)
K.1.4 Intermediate transfer
K.1.5 Access control
K.2 Trapped key interlocking system configuration process
K.2.1 General
K.2.2 Intermediate transfer
K.2.3 Trapped key solenoid-controlled switch
K.3 Selection of trapped key interlocking devices
K.3.1 General
K.3.2 Energy control
K.3.3 Intermediate transfer
K.3.4 Access control
K.4 Examples of trapped key interlock devices
K.4.1 Key-operated switch
K.4.2 Bolt lock
K.4.3 Access lock with personnel key
K.4.4 Key exchange device
K.4.5 Mixing machinery — Trapped key system controlling multiple guards and sources of energy
K.5 Example of separate safety functions
K.5.1 General
K.5.2 Guard-locking function
K.5.3 Prevention of unexpected start-up (in an unlocked condition)
Bibliography
Cited references in this standard
[Current]
Safety of machinery — General principles for design — Risk assessment and risk reduction
[Current]
Safety of machinery — Safety-related parts of control systems — Part 1: General principles for design
[Current]
Safety of machinery — Safety-related parts of control systems — Part 2: Validation
ISO 13855:—
Safety of machinery — Positioning of safeguards with respect to the approach speeds of parts of the human body
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