Safety door switches detect the opening of guards or doors to prevent unauthorised access to hazardous, restricted or important areas and ensure the safe implementation of emergency equipment stoppages.

Locks commonly used in safety door switches

There are two commonly-used locks used in safety door switches. A mechanical lock is used in some electromagnetically-locked safety door switches, and locks automatically when the operating key is inserted. You can lock and unlock manually using a key lock at any time.

On the other hand, a solenoid lock features a latch for both electrical locking and unlocking. These locks are available with ‘power-on unlocking’, which keeps the switch locked in case of power outages/failure. This can be commonly seen in prisons to prevent the inmates from escaping in case of a power failure.

Choosing the right safety door switch for you

OMRON is committed to helping create productive industrial automation environments without compromising on safety. We offer a wide range of safety door switches for a variety of applications.

OMRON’s D4NS series safety door switches are effective for both standard and micro loads. They are multi-contact, environmentally friendly and easy to install, maintain and replace. For those applications where a smaller part is needed, our D4NH safety door hinge switches are designed to save space in machines and other equipment.

We also offer magnetic non-contact safety switches, which are easy to install and ideal for dusty and wash-down environments. The D40Z series can be used on high-risk applications when connected to a safety controller. Its safety features include stable detection even when the door closes slowly, self-diagnostic function and LED indication patterns, and it can support centralised monitoring.

OMRON also has a wide range of guard-locking safety door switches. The D4SL series is perfect for a wide variety of applications and the D4JL series is designed for large, heavy doors. Both have a lockout or trap key to prevent people being trapped inside a hazardous area.

OMRON’s safety door switches make it easy to prevent industrial accidents. Operators and workers can work with a peace of mind in a safe and worry-free production site.

What is a safety limit switch?

Safety limit switches are used as control and safety devices for machinery and personnel. They can accurately detect the presence of objects and send a digital signal to the control system, prompting it to take appropriate action. For example, a safety limit switch can be used to detect the opening of a safety guard that stops and halts the machine.

How does a safety limit switch differ from a general limit switch?

Safety limit switches are provided with a direct drive positive opening mechanism (positive actuation structure) with which welded portions are forcibly torn even if contact welding occurs, stopping a dangerous process (load) and performing safe operation.

General limit switches do not include this mechanism. If contact welding occurs, it keeps conduction state, and thus it cannot reliably stop dangerous process (load) and may perform dangerous operation.

Selecting the appropriate safety limit switch

The D4F series offers a slim body and robust metal housing. A pre-wired version is available for easy installation. It is perfect for heavy-duty machines with limited space, long periods of continued usage and severe environments. Its high sensitivity helps to reduce any unplanned downtime.

Next is the versatile D4N series. Its plastic housing makes it the ideal switch for all standard mechanical positions for detection applications. M12 connector options and a wide variety of actuators reduce your installation costs and simplify your troubleshooting activities.

The D4N-R series offers manual reset, plastic housing, M20 and M12 connector options, and a wide range of actuator types. This series is ideal for overtravel detection of elevators, moving table and other similar applications.

Lastly, our D4B-N series is built with rugged metal housing and increased temperature range to thrive in harsh environments. Its enhanced mechanical lifetime, flexible mounting, and M12 connector types offer long durability and effortless maintenance.

OMRON’s safety limit switches can enhance personnel safety by safeguarding operators and employees from potential harm, and can protect machinery from unintentional damage.

What is a safety limit switch?

In the modern industrial workplace, guards and fencing are often required to keep operators safe from hazards. Some guards are mechanically fixed into place, while others can be opened and closed by operators.

Safety interlock switches are used to detect the opening of guards or doors, and prevent access to hazardous areas. When the hazardous area is accessed, the power supply to the machine is disengaged.

Benefits of safety-rated interlock switches

Safety interlock switches help prevent industrial accidents and minimise the risk of injury. By installing safety-rated interlock switches, manufacturers can ensure a safe and worry-free production site.

OMRON’s range of safety interlock switches can mount to a number of different access mechanisms. Whether it be hinged, sliding or simply a lift-off mechanism, OMRON has an interlock you can apply.

Our newest interlocking switches are tougher and more adaptable, ready to make machinery safer than ever. These switches are easy to install and wire, providing a comprehensive safety solution.