Technical Guide

Safety Solutions

General Information

Safety Light Curtains

Safety Switches

Emergency Stop Switches

Safety Application Controllers

Safety Relays

Safety Light Curtains

Safety light curtains use blocked light to detect workers in hazardous machine areas and to stop machines before workers are injured. Unlike ordinary sensors, safety area sensors use a combination of hardware and software to check constantly for internal faults to ensure safe operation.

The following section describes the faults and malfunctions the F3SJ/F3SN detects to ensure safety.

• F3SJ/F3SN-A Safety Design

The sensor constantly checks its own internal circuits and looks for a disconnected cord or abnormal incidental light. Just as in entry detection, this sensor sends out an OFF signal and completely shuts OFF machinery in the rare instance when trouble occurs.

(1) Compliance with Machinery Directive

The safety standards for safety area sensors are the same requirements stipulated for safety in the Machinery Directive, and European standards like IEC61496 ensure compliance with those requirements. IEC61496-1 stipulates exactly how type 4 ESPE will ensure safety for an accumulation of up to three faults. In the F3SJ, F3SN-A, F3SH-A, F3SS and MS4800 safety was designed in by using dual CPUs that check each other as well as by using redundant signal processing and output circuits. FMEA * analysis was also used to demonstrate safe operation and thus ensure complete safety.

* FMEA: Failure model and effects analysis

(2) Applications

The F3SJ, F3SN-A, F3SH-A and MS4800 Safety Light Curtains and F3SS Single-beam Safety Sensor can be used even with the most hazardous machines. (EC Machinery Directive Type 4)

These products can be used for all applications in categories B, 1, 2, 3, and 4 (ISO 13849-1) for safety-related parts produced for machine hazards. The F3SN-B and E3FS/E3ZS Single-beam Safety Sensors *, which are Type 2 Safety Area Sensors, can be used for applications in categories B, 1, and 2.

* Used as a set with the special Controller.

(3) Press Safety Standards

When safety area sensors are to be used with press equipment in Japan, they must pass the “model test” stipulated in Article 44, Item 2, of the Occupational Health and Safety Law. The F3SJ, F3SN, F3SH and MS4800 have not been subjected to this model test, so they cannot be used in the applications described in Article 42 of the Occupational Health and Safety Law as “Safety devices for presses or shearing machines.”

(4) Safety Distances

When installing a presence-sensing device, such as a Safety Light Curtain, the minimal distance that is required to stop the machine before a person who enters the detection zone will reach the machine is stipulated by EN999 and other standards.

• Calculating the safety distance based on ISO13855 (EN999)

Safety distance (S) = Person’s approach speed × response time + additional distance due to the sensor’s detection capability

When the installation position is switched, the safety distance is calculated in response to the resulting conditions.

 

General formula		S = K × T + C
d ≤ 40 mm	100 mm ≤ S ≤ 500 mm	S = (2,000 mm/s × T) + 8 (d-14 mm)
	S > 500 mm	S = (1,600 mm/s × T) + 8 (d-14 mm)
40 mm < d ≤ 70 mm		S = (1,600 mm/s × T) + 850 mm
Single beam		S = (1,600 mm/s × T) + 1,200 mm

(5) Muting Function (IEC 61496-1)

The muting function temporarily stops the detection function of the Safety Light Curtain and automatically keeps it ON regardless of whether the light is incident or interrupted.

The muting function can be added to the Safety Light Curtain by connecting the F3SP-U2P Muting controller or by connecting the Safety Light Curtain with accessories (F3SJ + Muting Cap).

Conventionally when objects such as AGVs or transport pallets passed through the detection area, the work process was stopped by the light interruption of the Safety Light Curtain each time they passed. With the addition of the muting function, the safety output can be turned OFF only when a person enters the area, while automatically maintaining the safety output when a workpiece passes through. This makes it possible for work to continue without stopping the production line.

However, when muted, the safety detection function is deactivated, which means that it cannot output an OFF signal to the hazard source when a person enters the detection area.

• Installation

The following items are necessary to add the muting function.

(Example)
F3SN-A Safety Light Curtain: 1 set
F3SP-U2P Muting Controller: 1
E3Z-R81 Muting Sensors: 2 sets
Muting Lamp (OMRON recommended product): 1

Note: The F3SP-U2P Muting Controller distinguishes the difference between a workpiece and a person passing through by the difference in the detection timing of Muting Sensors A and B. Adjust the installation locations and detection directions of Muting Sensors A and B so that the light will not be interrupted in both when a person passes through.

Workpieces and persons are distinguished by multiple Muting Sensors. Because a dangerous situation may occur if the installation positions and other factors are not correct for the Muting Sensors, have a person with sufficient knowledge and experience perform a risk assessment when deciding the selection, installation locations, detection directions, and other factors for the Muting Sensors.

For more details, refer to the operation manual for the F3SP-U2P Muting Controller.

• Prior to Use

It is necessary to alert people in the vicinity when muting is being used. A Muting Lamp must be installed for this purpose. Also, the F3SP-U2P is equipped with an override function that forcibly applies muting. The safety output is explicitly disabled by this function, so ample safety considerations must be made in it use.

Example of Improper Use
• No Muting Lamp installed.
• Persons approach a hazard source during muting.

Example of Proper Use

• A Muting Lamp is installed to inform people in the vicinity that muting is being used and the safety detection function is being disabled.

• Persons do not approach a hazard source during muting.

6) Blanking Application

● Fixed Blanking:

Some applications have problems in mounting the light curtain. Therefore it is helpful to take out zones from the protection field. With the blanking function it is possible to specify beams that will not be interrupted by the light curtain. This is called fixed blanking. The remaining field or zone has to be protected by mechanical guards.

● Floating Blanking:

The floating blanking function allows the output to remain ON when beams of the sensor are interrupted anywhere in the protection field. In contrast with fixed blanking function, which invalidates the fixed detection area, the floating blanking function ignores objects smaller than a specified radius. This reduces the optical resolution.

 

(1): No detection	(2): Detection of 1 beam
(3): Moving of work piece (Detection of 1 beam)	(4): Detection of 2 beams (Detection of a value exceeding the set value)

Application Example: Wire or Tape Take-up Winder
When it is not possible to provide the entire take-up winder with a safety cover or other device.

For calculating the safety distance this reduced resolution has to be taken into account. (See table below.)

* Can be set only with the F3SJ series

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