In industrial automation, safety takes precedence to protect lives and processes. Understanding the nuances between safety contactors and standard contactors is crucial in ensuring the utmost safety and reliability. In this blog post, we’ll delve into the key distinctions and applications of safety contactors and standard contactors, emphasizing safety automation and design principles.
Understanding the Emergency stop Button
Common E-stop Problems
Wiring and Connection Issues
The most common wiring error is cross wiring the test pulses in to e-stop inputs.
We’ll use the below example to explain this. Nelow is an implementation of a dual channel estop with a ReeR M1 MOSAIC Safety PLC System. With:
Inputs: PIN 17 & 18
Test Outputs: PIN 13 & 14
Safety OSSD Outputs: PIN 5 & 6
Reset: PIN 7
What is cross wiring?
Cross wiring is when the incorrect test pulse is wired to the incorrect input in resulting in the machine not turning on (Green light on). This can be identified by the flashing yellow/orange lights on the M1 inputs 1 and 2.
Following the example above, test pulse from PIN 13 incorrectly goes into Input PIN 18, and test pulse from PIN 14 incorrectly goes into Input PIN 17.
PIN 13 → PIN 18
PIN 14 → PIN 17
Once correctly wiring the system, the estop should work as normal.
PIN 13 → PIN 17
PIN 14 → PIN 18
Other Possible Issues
Faulty/Broken Safety Relay or PLC
In certain situations, the reliability of an emergency stop (E-stop) system can be compromised when the safety relay or programmable logic controller (PLC) becomes faulty or damaged, necessitating replacement.
Occasionally, the effectiveness of an emergency stop (E-stop) system can be compromised when the E-stop button head is improperly connected to the contact block. This vital interface ensures that when the E-stop button is pressed, it effectively breaks the electrical circuit, halting machinery and equipment.
Software of Control System Issues
In complex machinery with integrated control systems or PLCs, adjustments or reprogramming of the safety system may be necessary to ensure proper E-stop functionality, as issues within the software or programming logic can hinder the E-stop reset process.
E-stop button Damaged
The E-stop button is crucial for safety in industrial applications and should be inspected periodically for physical damage or wear to ensure it functions properly. Malfunctions are often caused by damage or wear to the button/device. Inspect for cracked or warped components and proper connection/functioning. Taking proactive measures ensures the E-stop system is ready to serve its safety function.