Brief Introduction to Safety Interlock Switches: Types, Uses, Features

This article was last updated on July 26, 2022

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Safety interlock switches are used for controlling the safe opening and interlocking of guards and covers. They help close off spaces and prevent doors and guards’ opening whenever a machine is in operation; the door or guard can only be accessed once the machine has seized operating and it’s safe to enter the area.

Safety interlock switches are extremely crucial pieces of hardware that are instrumental in terms of personnel safety, as they can be used to shut off power and prevent machines from becoming operational while the guard is open.

By allowing or denying access to personnel, interlock switches add a layer of safety in industrial production environments, providing a safe working atmosphere for operators and equipment from hazardous events like unexpected machine motion. Once a safety interlock switch has been set into the safety circuit, they ensure that machines can only begin functioning once the door or gates are closed.

They are used across a wide range of applications, including semiconductor manufacturing, packaging and production lines, material handling equipment, etc. safety interlock switches play a vital role across a wide array of industries and applications.

Uses of Safety Interlocks

·      They are used where delayed machine stopping or uncontrolled interruption of a running process could result in serious injuries or even death.

·      Used to prevent any attempts of switch override and to tamper with the system

·      Machinery or equipment that requires frequent access or have a possibility of causing injury or death

·      Used where access to machinery and equipment requires frequent access, and there is a risk of injury or death if there are no tabs on access control.

Types of Safety Locks

Standard Mechanical Safety Interlocks: this is one of the most common types of safety interlock and is referred to as a functional category 2 devices per international and European standards. It comes with two components: the safety interlocking housing and a coded actuator. The latter is usually mounted onto the gate and is aligned to the housing slot mounted on the structure.

Rotary and Hinged Safety Interlocks: The rotary or hinged safety interlock device is specifically designed to be mounted on an access door’s hinged side. They are considered to be functional category 1 devices as per the international and European standards systems.

They are one-piece construction, where the actuator, unlike the standard mechanical safety actuator, is an integral part of the housing itself. Since these devices are mounted out-of-the-way in the frame of the machine, they have fewer chances of being exposed to dirt, oil, tampering, etc., making them more efficient.

Guard Locking Safety Interlocks: They come with a separate actuator and use a solenoid system to engage and lock the actuator. This results in the gate’s monitoring for open and closed positions and keeps the gate closed, preventing any access to the machine until the machine is verified to be in a safe state. This type of safety interlock switch is widely used for devices known to have long stopping times, and it can be dangerous to enter the premises unless the machine comes to a complete halt.

Magnetic Safety Interlocking: These are used in case it’s unfit to use mechanical safety locks due to environmental concerns, mechanical limitations, and size. It comes with a sensor and an actuator that’s magnetically coded.

Magnetically-actuated reed contacts are housed within the sensor, and it’s imperative that the reed contacts should match the coded actuator before the machine can become functional.

Safety interlocks are essential for personnel safety and are widely used across a wide array of industries to prevent unauthorized or uncontrolled access to areas deemed dangerous while operational. Therefore, it’s important to partner with a reputed electrical company, as that can help you acquire and install the highest-grade safety interlocks to ensure a safe working environment.