1 Scope
This document specifies the technical requirements for interlocking devices with protective locking and the requirements for information on their use. This document applies to interlocking devices with electromechanical protective locking or electromagnetic protective locking.
2 Normative references
The contents of the following documents constitute essential provisions of this document by means of normative references in the text. Where a reference is dated, only the version corresponding to that date applies to this document; where a reference is not dated, the latest version (including all amendment sheets) applies to this document.
3 Terms and definitions
The terms defined in GB/T15706, GB/T18831 and GB/T41108.1 and the following terms and definitions apply to this document.
3.1
Interlocking device with protective locking
An interlocking device in which the switching elements are kept in a locked state by means of a protective locking device.
3.2
Protection locking device
A device intended to lock a guard in the closed position and connected to the control system.
[Source: see GB/T18831--2017, 3.4]
3.3
Electromechanical protective locking device
Electromechanical devices capable of holding a movable guard in the closed position by means of a rigid element such as a pin or locking door driven by elastic or electromagnetic force, and with position monitoring functions.
Note 1: Electromechanical guarding locking devices achieve their safety function in the following ways:
They are held in the locked position by elastic force (spring-actuated) and unlocked by electromagnetic action;
The locking state is maintained by electromagnetic action and unlocked by elastic force (spring-actuated).
4 Requirements
4.1 General requirements
Interlocking devices with protective locking shall comply with the provisions of GB/T14048.5-2017 and shall also comply with the provisions of 4.2~4.8.
4.2 Structural requirements
4.2.1 Protective locking devices using contacts as output switching components should use direct break contacts with auxiliary normally open contacts (e.g. for signal indication); if the protective locking device uses type C or Za changeover contacts in accordance with GB/T 14048.5-2017, only normally closed contacts should be used for the safety function and the normally open contacts should not be occupied, and appropriate instructions should be given in the operating instructions. 4.2.1 The safety function shall only be used with normally closed contacts.
4.2.2 The protective locking device with metal housing shall be protected against earth faults by a protective earth.
4.3 Safety requirements
4.3.1 Electromechanical protective locking devices
4.3.1.1 Elastically actuated locking elements
When relying on spring-actuated locking elements to achieve the protective locking function, the locking element shall be held in the locked position by elastic force. The spring force can also be replaced by a magnetic force generated by a permanent magnet, but this force should not be reduced by external influences.
The spring force should be generated by a guided helical compression spring.
The spring used to hold the locking element in the locked position should be a proven element, see table A.3 in GB/T 16855.2-2015.
4.3.1.2 Electromagnetically actuated locking elements
Protective locking devices that rely on electromagnetically driven locking elements to achieve the protective locking function should operate normally within a range of 85% to 110% of the rated operating voltage.
AC coils may only be used if the circuit closure of the solenoid coil is not impeded or if unacceptable temperature rises can be excluded.
4.3.1.3 Protective locking monitoring
The safety locking device shall monitor the position of the safety guard and the locking element by means of a safety-related sensor. Only if the safety guard is in the safe position and the protective locking device is in the locked position can the switch-on command be issued in response to a hazardous condition.
If the active guard is closed, the locking element can only be brought into the locked position (fail-safe locking) and the position monitoring of the safety guard can be cancelled.
4.3.2 Electromagnetic protective locking device 4.3.2.1 Protective locking monitoring
To determine whether the specified locking force has been achieved and maintained, the electromagnetic protective locking device should be monitored.
4.3.3 Direct disconnection operation
4.3.3.1 The direct break normally closed contact of the protective locking device shall be reliably disconnected and shall remain open as long as the actuator is not inserted into the protective locking device.
4.3.3.2 The normally closed contact shall be reliably open and remain in the open position even in the event of mechanical failure of a component, e.g. a broken spring or a loose contact bridge.
4.3.3.3 The normal function of the protective locking device shall not be impaired even if it is driven from the most unfavourable drive angle. The manufacturer is advised to give the maximum drive angle.
4.3.3.4 Expected failures of mechanical components should not impair the protection against false closures. table A.5 of GB/T 16855,2-2015 gives the expected failures of mechanical components and their troubleshooting.
4.3.3.5 The safety-related spring used to actuate the protective locking device shall be generated by a compression spring. In addition, the spring should be a proven element, see table A.3 in GB/T 16855.2 - 2015.
4.3.4 Protective locking force
Interlocking devices with protective locking should not be subjected to forces (e.g. tension, shear, etc.) during normal use that would cause the protective locking function to fail. The protective locking force shall be not less than 1000 N, but shall not be greater than the holding force Fa determined in accordance with 5.7.4 of GB/T 18831-2017.
4.3.5 Protection against incorrect closure
Interlocking devices with protective locking should be protected against false closure, so that even if the mechanical components of the device fail, their normal function is not affected.
4.3.6 Average number of dangerous failure cycles (B1op>)
The Bop value of interlocking devices with protective locking shall not be less than 2,000,000 cycles.
4.3.7 Protective locking devices with logic units
For protective locking devices with logic units, the relevant requirements in GB/T 16855.1-2018 or GB 28526-2012 shall be met. The manufacturer shall give the performance level (PL) or safety integrity level (SIL) determined according to GB/T 16855.1-2018 or GB 28526-2012.
If the design is in accordance with GB 28526-2012 and complex structured components are used, it is also appropriate to consider the relevant requirements in GB/T 20438-2012.
If semiconductor switching elements are used in the logic unit, the requirements specified in Appendix H of GB/T 14048.5-2017 should be met.
4.3.8 Auxiliary unlocking of protective locking
4.3.8.1 Manual unlocking
If the protective locking device is equipped with a function for manual unlocking from outside the protective field, it shall only be unlocked manually by means of a tool or key, or only after opening the protective cover (e.g. protective housing) by means of a tool. Manual unlocking should be independent of the state of the solenoid.
During manual unlocking there should be no contact with electrically conductive parts.
Manual unlocking should only be reset by prudent handling. It can be reset by means of a tool or a key. After use, the manual unlocking should be closed again to prevent it from being altered.
Note: For more information see 5.7.5.4 in GB/T 18831-2017.
4.3.8.2 Emergency unlocking
If the protective locking device is equipped with an emergency unlocking function from the outside of the protective field, the protective guard (e.g. safety door) can be opened discreetly in a hazardous condition without any auxiliary measures and without regard to the operating status of the protective locking device.
The emergency unlocking mechanism shall be manually operated and shall act directly on the locking elements of the protective locking device.
4.4 Minimising the possibility of abandonment
4.4.1 General requirements
Interlocking devices with protective locking shall ensure that their safety function cannot be discarded in a simple and predictable manner.
It shall not be possible to actuate the switch by simple means (e.g. by coding), e.g. by hand or by easily accessible objects, so that the safety-relevant contacts (normally closed contacts) of the protective locking device are closed.
Examples of readily available objects are:
Screws, pins, metal sheets.
everyday items such as keys, coins, tape, binding wire
Tools, such as screwdrivers, spanners, pliers;
Objects that can be made by hand only (without other tools), e.g. folded cardboard.
Objects that can only be made by hand (without other tools), e.g. folded cardboard, should not be considered as readily available if they can only be made by tools or other equipment, require multiple steps and are intended to make the interlocking device obsolete.
It should not be possible to loosen the fasteners of the guard locking or actuators by hand or other readily available objects.
If the manufacturer provides fasteners with the locking guards and/or actuators, the fasteners should be one-way screws.
Note: For more information on design measures to minimise the possibility of abandonment, see Chapter 7 of GB/T 18831-2017.
4.5 Mechanical strength
Protective locking devices should have sufficient mechanical strength. When subjected to vibration or shock during its intended use, the protective locking device should function properly and should not suffer from:
separation or loosening of the components of the protective locking device
Damage affecting function and safety
Physically accessible live elements.
4.6 Mechanical life
Interlocking devices with protective locking shall have a mechanical life of at least 1,000,000 cycles.
4.7 Enclosure protection class
The manufacturer shall determine the enclosure protection class (IP code) of the interlocking device with protective locking in accordance with GB/T 4208-2017.
Note: The actuator is inserted into the position switch and therefore there are openings in the position switch that lead to dust ingress. the IP code relates to the electrical enclosure only. Contamination of mechanical components can impair the performance of the interlocking device and lead to dangerous failures.
4.8 Electromagnetic compatibility (EMC)
The electromagnetic compatibility of interlocking devices with protective locking shall comply with the requirements specified in 7.3 of GB/T 14048.5-2017.
5 Information on use
5.1 General requirements
The information provided to the user and its presentation shall comply with 6.4 in GB/T 15706-2012.
Note:For more information on usage information, see ISO 20607:2019.
5.2 Shell marking
Bibliography
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Requirements
5 Information on use
Bibliography
