Wuxi Rihuan Sensing Technology Co., Ltd.will introduce to you the equipment that has installed safety photoelectric barriers, and how to connect the emergency stop signal? 

In many industrial equipment, even if safety grilles have been installed, additional emergency stop signals need to be connected to achieve dual safety protection. So, how should different output types of grilles be connected in series with the emergency stop button? Here are the wiring methods for two common situations. 

Situation 1: The light sensor outputs as NPN or PNP (transistor output)

The safety light sensor with NPN or PNP output cannot be directly connected in series with the contacts of the emergency stop button because their signal types are different. The correct approach is: 

Connect the NPN or PNP output signals of the grating to the coil of an intermediate relay first. 

Connect one group of normally open (or normally closed) contacts of this intermediate relay in series with the contact of the emergency stop button. 

The combined signal is then connected to the safety control loop of the equipment. 

In this way, whether the raster is blocked or the emergency stop is captured, the power supply of the equipment can be reliably cut off. 

Case 2: The grating outputs as a relay signal (contact signal)

If the safety grating itself outputs as a relay contact signal (that is, the output is an inactive switch quantity signal), then the wiring is simpler: 

Just connect the output contacts of the grating directly in series with the contacts of the emergency stop button. 

The connected circuit is then connected to the safety control circuit of the equipment. 

Important Safety Precautions

The emergency stop signal must use safe voltage: According to the original text, the voltage of the emergency stop-related lines should be controlled below 36V (i.e., safe extra-low voltage) to ensure the personal safety of the operators. 

When making modifications or wiring, the main power supply of the equipment should be cut off, and the operation should be carried out by personnel with electrical knowledge. 

After completing the wiring, a functional test must be conducted: activate the light barrier and press the emergency stop button respectively, and confirm that the equipment can stop reliably. 

Summary

Correctly connecting the emergency stop signal can make up for the protection blind zone of the raster in certain abnormal situations, which is an effective measure to enhance the safety level of the equipment. 

Rihuan Sensor offers a variety of safety grating products with NPN, PNP and relay outputs, and can provide users with clear wiring diagrams and technical support. Welcome to follow Dayuan Sensor to obtain safer and more reliable sensor solutions.