主要变化引进 EN ISO 14119: 2013

a. 联锁设备的新细分(见注1):

 1级装置-未编码

可用于:

• 旋转凸轮
• 线性凸轮
• 铰链

A: 可移动保护 - B:致动器 (cam) - C:位置开关 - 1:打开方向

图. 1 -旋转凸轮驱动位置开关 1级联锁装置A: 可移动保护  -  B: 致动器 (cam) - C: 位置开关 - 1: 打开方向

图. 2 -线性凸轮驱动位置开关 1级联锁装置

A: 可移动保护  - B: 铰链联锁装置  - C: 保护固定部分

图. 3 - 铰链联锁装置

2级 - 编码

这些可以(见注2):

• 以编解码器的插销致动器位置开关
• 受限联锁钥匙.

1: 位置开关- 2:插销

Fig. 4 - 位置开关和插销

1: 开关- 2:螺栓锁

Fig. 5 - 受限联锁钥匙原理

3级 - 未编码

可用于:

• 感应——驱动金属
• 磁 - 未编码的磁铁驱动
• 电容-超声波或光学.

                                       关闭的可移动防护                                                     未关闭的可移动防护 

1: 可移动防护 - 2: 联锁装置 - 3: 致动器(电感、磁或电容) -
4: 接近开关 - 5: 致动系统 - 6: 输出系统

图. 6 - 由未编码的致动器驱动的接近开关联锁装置

Type 4 - Coded

These can be (see note 2):

• Magnetic - Actuated by coded magnet
• RFID
• Optical - Actuated by coded optics

1: Opening direction - 2: Type 4 interlocking device - 3: coded magnet actuator - 4: Movable guard 

Fig. 7 - Example of type 4 interlocking device with position switch actuated by coded magnetic actuator

1: Opening direction - 2: Type 4 interlocking device - 3: coded RFID tag actuator - 4: Movable guard

Fig. 8 - Example of type 4 interlocking device with position switch actuated by coded RFID tag actuator

b. Overall system stopping performance and access time (The gards distance)

The access time shall be calculated by using the distance between the hazard zone and the guard together with the approcach speed (see ISO 13855:2010 for typical values).

c. Logical series connection of interlocking devices

Logical series connection of interlocking device means for NC contacts wired in series or for NO contacts wired in parallel.

When interlocking device with redundant  contacts are logically connected in series the detection of a single fault can be masked by the actuation of any interlocking device logically conected in series with the defective interlocking device to the safety related control system.

It is foreseeable that during the fault finding (troubleshooting) by the operator one of the guards whose interlocking devices are logically connected in series with the defective interlocking device will be actuated. In that case the fault will be masked and the effect on the diagnostic coverage value shell be considered.

For a series connection the maximum DC (see ISO 13849-1 or IEC 62061) should be considered.

Up to now, for a logical series of NC contacts, it is considered a DC = 60%, allowing you to get a PL d (not a PL e). The masking of faults, could lead to a lower diagnostic coverage, so nothing.
Based on DC = λdd / λd (ratio of detected dangerous failures and total) can easily lead to a DC <60%.

d. Interlocking devices based on "fault exclusion"

The standard specifies that the maximum safety level reached by interlocking devices based on "fault exclusion" is generally PLd. In fact there is the possibility that a single mechanical failure resulting in the loss of the safety function.

For example a mechanical failure relating to the key (actuator), or some part of the mechanical device can generate false information on the electrical contact output.

In some cases it is still possible reach the safety level PLe. These are cases of "fault exclusion for the guard locking".
The safety level reached in these cases is not necessarily limited by the faults exclusion of the mechanical locking device.

However, specific requirements must be verified: the holding force specified (FZH) of the protection guard locking device must be sufficient to withstand static forces planned on locking bolt, it is also necessary to prevent any effect on the protection locking device determined by the forces dynamic due to movement of the protection guard.

e. Guard lock and Guard interlock

The standard emphasizes the fact that the interlock function and the lock function are two separate safety functions with PLR that can also be different (PLr Locking <PLr interlock).

f. Measures to prevent the defeat of the interlock device

Guards and protection devices of the machines should not be easy to by-pass or render non-operational (Directive 2006/42/EC §1.4.1). Measures required to minimize tampering (see note 3).

Measures to reduce the defeat of interlocking devices may be adopted:

• Prevent access to the elements which constitute the interlock device: Mouting out of reach, physical obstruction / shielding, Mounting in hidden position).
• Preventing substitution of the actuators using encoded interlocking devices.
• Prevent disassembly or moving of the interlocking devices (welding, gluing, riveting, etc ..).
• Status monitoring or cyclic testing of the intelocking device.
• Adding an additional interlock device with a different principle of implementation. In this case, you will testing diving the plausibility of the state of both devices.

the table 3 of the standard ISO 14119:2013 specify the additional measures against defeating interlocking devices depending on type.

The anti-tampering measures in case of magnetic sensors low level encoding(MAGNUS) 

Mandatory:

• Mouting out of reach places, or mounting recesses and not visible in the machine, or status monitoring.
• Mounting the actuator so that it is difficult to remove.

Advice: