The Siemens 3SB5204-0UC01 is a red mushroom actuator for Emergency Stop applications, featuring a 40 mm diameter actuator, holder and 1NC Mounting Monitoring Contact Block (MMCB). It belongs to the Siemens 3SB5 range of industrial pushbuttons and emergency-stop devices. Current Siemens price-list documentation identifies the 3SB5204-0UC01 specifically as a “Mushroom Actuator, E-Stop (40mm) with MMCB (1NC)” in red.
The device is designed for machine-control panels and operator stations where an emergency-stop actuator with monitoring functionality is required.
The 3SB5204-0UC01 uses a prominent 40 mm mushroom actuator that can be used as an Emergency Stop operating element.
Its large red actuator makes the emergency-stop control easy to identify on industrial operator panels.
Typical applications include:
The emergency-stop circuit must always be designed and installed according to the applicable machine-safety requirements.
The actuator has a 40 mm diameter red mushroom-style operating surface. The prominent design provides an easily identifiable emergency-stop control for operators.
The product is described by suppliers as a maintained emergency-stop mushroom pushbutton with turn-to-release operation, with a holder and 1 NC contact configuration.
The red mushroom actuator is suitable where emergency-stop controls need to be clearly distinguished from ordinary operator pushbuttons.
One of the key features of the 3SB5204-0UC01 is its integrated MMCB (Mounting Monitoring Contact Block) with 1NC configuration.
The Siemens product listing specifically identifies the separate 3SB5400-0M as the MMCB (Mounting Monitoring Contact Block, 1NC) and states that the MMCB should be assembled only on the middle “5-6” slot of the holder.
This monitoring arrangement is intended to provide additional monitoring of the mounting/assembly condition of the emergency-stop device.
The 3SB5204-0UC01 is specified with a 1NC (Normally Closed) contact arrangement.
NC contacts are commonly used within emergency-stop control circuits because the control circuit can be designed to monitor the normal and operated states of the emergency-stop device.
The actual safety function, contact logic and circuit architecture should be determined by the machine's safety design and applicable standards.
The product is listed as a maintained emergency-stop device with turn-to-release operation.
This means the mushroom actuator remains in its actuated state after being pressed and requires a deliberate turning action to release it.
This type of operation helps prevent the emergency-stop device from automatically returning to its normal position after activation.
Although the mushroom actuator itself has a 40 mm diameter, the product is designed around the 22 mm Siemens 3SB5 panel-mounting system. Product listings specify the combination as a 22 mm round plastic emergency-stop pushbutton with a 40 mm actuator.
This makes it suitable for integration with Siemens 3SB5 operator panels and compatible control-panel components.
The Siemens 3SB5204-0UC01 can be used in various industrial applications, including:
The 3SB5204-0UC01 is suitable for OEM machine manufacturers, electrical panel builders, automation integrators and industrial maintenance teams.
Its combination of a red 40 mm mushroom actuator, maintained turn-to-release operation and 1NC mounting-monitoring contact makes it useful when designing emergency-stop interfaces with additional mounting-condition monitoring.
The Siemens 3SB5204-0UC01 combines a clearly visible 40 mm red mushroom actuator with 1NC mounting monitoring functionality in a compact Siemens 3SB5 emergency-stop solution.
Its maintained turn-to-release operation provides deliberate reset action, while the MMCB adds mounting-condition monitoring. Siemens documentation specifically identifies the product as an E-Stop mushroom actuator with MMCB (1NC).
For OEMs and panel builders, it provides a practical solution for integrating emergency-stop controls into industrial machine and automation panels.
For related Siemens industrial electrical and automation products, customers can explore the Siemens product range available from SB Smart.
It is a Siemens 3SB5 emergency-stop mushroom actuator with a 40 mm red actuator and 1NC MMCB.
The mushroom actuator has a 40 mm diameter.
The actuator is red.
MMCB stands for Mounting Monitoring Contact Block. The 3SB5400-0M is the associated 1NC MMCB listed for this product family.
The specified configuration includes 1 NC contact.
Yes. The product is specified as a maintained emergency-stop device.
It uses a turn-to-release mechanism.
The product is designed for the 22 mm Siemens 3SB5 panel system, while the mushroom actuator itself is 40 mm in diameter.
It can be used in industrial machinery, automation panels, production lines, conveyors, packaging machines, OEM equipment and machine-control stations.
You can explore the Siemens product range at SB Smart for Siemens emergency-stop pushbuttons, mushroom actuators, contact blocks and other industrial automation products.
| Parameter | Specification |
|---|---|
| Product Series | Siemens SIRIUS ACT / 3SB5 |
| Model Number | 3SB5204-0UC01 |
| Product Type | Key Operated Selector Switch |
| Operation Type | Key Operated |
| Mounting Diameter | 22 mm |
| Design | Round |
| Mounting Type | Panel Mount |
| Holder | Included |
| Compatibility | SIRIUS ACT Contact Blocks |
| Application | Control & Security Functions |
| Brand | Siemens |
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