Wiring Diagram of Emergency Stop Button and Safety Relay: How to Properly Connect for Safety?
What Is the Connection Between the Emergency Stop Button and the Safety Relay?
The emergency stop button and the safety relay are two closely interconnected key components in industrial safety systems. They work together to ensure that, in emergency situations, equipment can be quickly and safely stopped, protecting both personnel and machinery. Below is a detailed explanation of their connection:
Functional Connection
1. Implementation of Emergency Stop Function:
The emergency stop button serves as an input device. When an operator presses it in an emergency, it sends a trigger signal to the safety relay. Upon receiving this signal, the safety relay immediately executes the appropriate safety logic, such as cutting off the power supply or control circuit, thereby stopping the equipment operation.
2. Safety Interlock Function:
The emergency stop button and safety relay can form a safety interlock circuit along with other safety devices, such as safety door switches and safety light curtains. The equipment can only operate normally when all safety conditions are met. If any safety condition is violated—such as the emergency stop button being pressed—the safety relay will immediately cut off the power supply to ensure safety.
Operational Principle Connection
1. Signal Transmission and Processing:
The emergency stop button is typically a normally closed contact. When not pressed, the contact remains closed, allowing current to pass through. When pressed, the contact opens, interrupting the current. The safety relay continuously monitors this current change. If it detects an interruption, it triggers its internal safety mechanism to cut off the output circuit, achieving an emergency stop.
2. Redundancy and Monitoring:
To enhance system reliability and safety, the emergency stop button and safety relay often incorporate redundancy designs. For example, the safety relay monitors two separate channels of the emergency stop button to ensure signal accuracy and integrity. If a fault or signal anomaly occurs in any channel, the safety relay can detect it in time and take appropriate safety measures.
Application Scenario Connection
1. Industrial Equipment Safety Protection:
In various industrial equipment, such as machine tools, automated production lines, and robotic systems, emergency stop buttons and safety relays are widely used in safety protection systems. They work together to ensure that, in case of equipment failure or operator danger, the equipment can be stopped quickly to prevent accidents.
2. Compliance with Safety Standards:
The combination of emergency stop buttons and safety relays helps equipment meet relevant safety standards and regulations, such as ISO 13849-1 and IEC 62061. These standards specify requirements for equipment safety performance, reliability, and fault detection. Through their design and functionality, emergency stop buttons and safety relays effectively fulfill these requirements.
Safety Standard Connection
1. Performance Level Requirements:
Both emergency stop buttons and safety relays must meet certain performance level requirements in their design and application. For example, in emergency stop systems requiring SIL3 or PLe levels, the safety relay must incorporate redundant structural design, sensor monitoring, and circuit monitoring functions. Similarly, the emergency stop button must comply with corresponding standards to ensure the safety and reliability of the entire system.
2. Fault Detection and Handling:
Both components must have fault detection capabilities. The safety relay continuously monitors the input signal from the emergency stop button as well as its own output status. If a fault or abnormal condition is detected, it will take immediate action, such as cutting off power or triggering an alarm signal, to ensure the safe operation of the system.
Wiring Diagram of Emergency Stop Button and Safety Relay: How to Properly Connect for Safety?
4 Emergency Stop Buttons Wiring to a Safety Relay
Functional Features
▪️Four-Way Emergency Stop Button (LS-2A4S):With its multi-channel capability, it enables more complex control logic and functions. For example, it can simultaneously cut off power to multiple devices or trigger emergency stops in different areas. This makes it ideal for complex systems requiring centralized control over multiple devices or zones.
Input Components: CH1 (E-Stop Button); CH2 (E-Stop Button); CH3 (Reset Button)
Input Components: CH4 (E-Stop Button); CH5 (E-Stop Button); CH6 (Reset Button)
Control Logic: CH1 & CH2, CH4 & CH5
Reset Mode: Manual Reset
Output Delay: 0 s
Safety Category: Cat. 4
Performance Level: PL e
Safety Integrity Level: SIL 3
Emergency Stop Safety Relay - Dual Channel Wiring
Functional Features
▪️Dual-Channel Emergency Stop Button (LS-3A1B.C):
Provides redundant protection—if one channel fails, the other remains operational, ensuring the effectiveness of the emergency stop function. This design minimizes the risk of emergency stop failure due to a single-point fault.
Dual-Channel E-Stop Button Input
Short-Circuit Monitoring Between Channels
Manual Reset
With Output Contact Feedback
Suitable for the Highest Safety Category 4
Components:
S1: Dual-Channel E-Stop Button
S3: Reset Button
K7, K8: Contactors
F1: External Fuse Protection
M1: Motor
Where Should Emergency Stop Buttons Be Installed?
1. Operation Control Stations:
Every operation control station should be equipped with an emergency stop button to allow operators to quickly halt equipment operation in case of an emergency.
For portable operation control stations, all emergency stop devices should remain active, and their ability to properly trigger the emergency stop function must be ensured during use.
2. Entry and Exit Points:
Installing emergency stop buttons at machine entry and exit points ensures that personnel in these critical areas can quickly reach and operate them to stop the equipment and prevent hazards.
3. Human-Machine Interaction Areas:
Any designated human-machine interaction areas, such as loading/unloading zones, should have emergency stop buttons to ensure operators can immediately halt equipment operation in case of an emergency.
4. Fire Protection Zones:
Emergency stop buttons should be installed near the main entrances and exits of fire protection zones. The walking distance from any point within a fire protection zone to the nearest emergency stop button should not exceed 30 meters to ensure rapid access in case of an emergency.
5. Around Equipment:
Emergency stop buttons should be strategically placed around equipment, particularly at critical locations such as operation platforms of large machinery and elevated work platforms. The installation should consider the specific requirements of the equipment and the operational habits of the personnel to ensure accessibility from different positions around the equipment.
6. On Specific Equipment:
For certain types of equipment, such as escalators, emergency stop buttons are typically installed at both ends of the escalator on the lower right side, as well as in the middle for long escalators.
7. Installation Height:
The installation height of emergency stop buttons should take into account the user's height and operational habits, typically ranging between 1.2 meters to 1.5 meters from the ground.
Which Emergency Stop Button Should I Press If the Equipment Suddenly Malfunctions?
If the equipment suddenly malfunctions, you should immediately press the nearest emergency stop button to quickly halt the operation and minimize potential risks or damage. The emergency stop button locations mentioned above are key areas you should familiarize yourself with during your daily work.
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Beam spacing: 30mm
Number of optical axes: 42
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