Switches and Disconnects
ML Disconnect Switches
The regulations EN 60204 part 1 and DIN VDE 0113 part 1 apply to the safety of machinery and the electrical equipment of machines.
Main switches are described in paragraph 5.3 and emergencystop equipment in paragraph 10.7.
A manually operated main switch must be provided for every main circuit. It must be a switch-disconnector corresponding to utilization category AC23 (IEC 947-3), fulfilling the following requirements:
- Disconnecting the electrical equipment from the main.
- Visible contact indication or a disconnection function by construction (the handle is in the “OFF” position when all contacts are open).
- If the main switch serves simultaneously as an emergencystop switch, its handle should be red. Otherwise, black or gray handles are recommended.
- It should be padlockable in the off position.
- All active conductors are to be disconnected from the main. The breaking capacity should be sufficient to break the current of the largest motor in a blocked state together with the sum of the operating currents of the remaining motors/loads.
- The handle of the main switch must be easily accessible and must lie between 24” – 74” (0.6 – 1.9 m) above the incomer level.
The main switch may fulfill the function of an emergency-stop switch on certain machines. The handles must be red on a yellow background. The contacts of a manually operated emergencystop switch have to be opened by force (positive opening).
Mounting styles and availability by type
Front (Flush) Mounting
Central Mounting: This through-the-door method requires no tools; the switch mounts with the supplied mounting ring, handle and adapter tab (which allows mounting in holes with diameters of either 22.5 mm or 30 mm). The handle and adapter tab mount on the outside of the door; the switch and mounting ring inside.
4-hole Mounting: Four screws go through the door, securing the front of the switch to the inside of the door and the handle/lever to the exterior.
Rear Panel or DIN Rail Mounting: The switch is rear mounted, either with screws to the back of a panel or on a DIN rail. The entire switch, including the lever, remains inside the panel.
Door Coupling: This through-the-door method is used on a hinged door and allows the handle/lever to remain in place as the door is opened and closed. The switch is rear mounted via DIN rail or screws, and the handle/lever and door coupling mechanism remain outside the panel. An optional extension shaft can compensate for the distance from rear of the panel to the front of the door.
Cover Coupling: This is similar to the door coupling, except it is used with unhinged doors. Door coupling hardware is not included and not necessary.