If you are looking for best-in-class safety solutions to protect your staff and your machines, I recommend checking out Allen Bradley’s extensive smart guard safety switches.
A Smart Guard Locking Safety Switch is a safety interlock switch with an internal solenoid that locks the switch in a closed or safe position. When applied to a safety guard door the intention is for the safety switch to lock the door in a closed position to restrict operators or anyone else access to the machine because there is a hazard that can inflict injury.
Smart guard locking switches differ from the standard interlock switch because interlock switches do not have the locking capability therefore anyone can gain access to the hazard by simply opening the door. Both styles are acceptable in safety circuits but not adequate for every safety circuit. Guard locking switches are usually applied when the hazard does not stop immediately after a stop command. Allen Bradley has a total of eight switches in their guard locking portfolio, but we will be focusing on three of them, the 440G-LZ, 440G-MZ, and the 442G-MAB. All these switches are SMART devices, they are solid state and have enhanced capabilities. On top of that, these devices have the highest safety rating of PLe/Cat. 4/SIL 3.
The 440G-LZSmart Safety Switch is intended to be used in a partial body access application which means it is installed on a small door that only allows a person to reach in with their hands. It has 1300 newtons of holding force and, unlike your typical safety switch that has a key or tongue that is inserted into the switch the LZ fires out a pin when given a signal to do so. The pin protrudes into the actuator and holds the door in place. The actuator has a RFID tag internally so you can monitor the door position and the pin will only fire out when the door is closed. There are built in LED’s for clear status indication and diagnostics.
The 440G-MZ Smart Safety Switch is the big brother to the LZ. It is intended to be applied in a full body access application which means the door it is installed on is a large door that allows a person to walk into the hazardous area. The flexible actuator give a wide tolerance for misalignment which is needed on full body access doors. It has 2500 newtons of holding force and the head has three openings to receive the actuator for diverse mounting options. This switch has GuardLink technology embedded into it but can also be used in a standalone circuit. GuardLink technology provides advanced enunciation, diagnostics and fault information.
The 442G-MAB Smart Safety Switch is the most comprehensive safety switch in the portfolio. MAB is short for Multi-function Access Box, it is designed for full body access doors and also includes the mechanical needs for a safety guard door. It can be used in a left-hand or right-hand application and has outputs for door position, bolt position, and lock status. There are two integrated hasps for applying locks when implementing LOTO. It also offers optional push buttons for local control such as lock, unlock, start, stop and reset. The MAB is the only switch that has Ethernet capabilities and can be applied in a CIP Safety circuit.
Allen Bradley has a full portfolio of safety switches and safety components to fit your application needs. Understanding which one to use for your application is the tricky part. Reach out to a Rumsey Safety Specialist for more information or assistance.
Joe LoMonaco is an Industrial Controls Specialist with Rumsey. Joe holds an Associates Degree in Electrical Construction and is TUV Function Safety Technician Certified. He has spent 10 years in the industrial machine safety industry, including five years as an electrician and five years supporting Allen Bradley automation sales.