Additional contact | 1NO+1NC | 3RH/3RT | top-mounted | screw terminals | SIEMENS | 3RH2911-1LA11

Technical specifications

Manufacturer: SIEMENS
Product type: auxiliary contact / auxiliary contact block
Contact configuration: 1NO + 1NC
NO contact: normally open
NC contact: normally closed
Contact marking: 73/74, 81/82
Mounting position: front part of the contactor / relay
Cable entry: from the top
Connection type: screw terminals
Compatibility: for SIEMENS 3RH and 3RT series contactors / contactor relays
Front protection class: IP20
Operating temperature: from -25 °C to +60 °C
Storage temperature: from -55 °C to +80 °C
Mechanical service life: up to 10,000,000 switching cycles
Electrical service life: approx. 200,000 switching cycles at AC-15, 230 V
Insulation voltage: 690 V
Impulse withstand voltage: 6 kV
Typical application area: control, signalling, interlocking and automation circuits

Functions

Contactor status transmission – allows a signal to be transmitted indicating whether the contactor / relay is switched on or off
Additional control contact – used when the main contactor does not have enough auxiliary contacts
1NO contact – normally open contact that closes when the contactor is actuated
1NC contact – normally closed contact that opens when the contactor is actuated
Signalling control – can switch on an indicator lamp, audible signal or another indication device
PLC / automation signal – suitable for transmitting the contactor status to a controller or automation system
Electrical interlocking – helps prevent incorrect simultaneous switching of several contactors
Control circuit expansion – allows the existing electrical control circuit to be supplemented with new functions
Front mounting on the contactor – conveniently mounted on a compatible SIEMENS 3RH / 3RT device
Screw terminal connection – ensures firm and reliable clamping of wires
Top cable entry – convenient when installing in an electrical panel where wires are routed from the upper side

Use

For electricians: This auxiliary contact is useful when installing or modernising electrical panels, automation cabinets, motor starting circuits, heating, ventilation, pump or production equipment control systems. Screw terminals allow a firm and clear wire connection.

For engineers / designers: Suitable for designing control circuits where additional contactor status information, interlocking logic or a signal to a PLC is required. The 1NO+1NC configuration allows the component to be flexibly adapted to different automation circuits.

For industrial equipment technicians: Useful for repairing or replacing existing SIEMENS SIRIUS contactor accessories. It can be used as a spare part in production lines, control cabinets, conveyors, pump systems or motor control units.

Advantages

Suitable for 3RH and 3RT series contactors / relays
1NO + 1NC contact configuration provides more control options
Convenient front mounting on the contactor
Top cable entry simplifies connection inside the panel
Screw terminals ensure firm wire clamping
Suitable for signalling, interlocking, indication and PLC control

Disadvantages

Designed only for compatible SIEMENS 3RH / 3RT series devices
Not suitable as an independent switch without a contactor or relay

FAQ

What is this auxiliary contact used for?
It is intended for additional control, signalling, indication or interlocking functions in contactor and contactor relay circuits. For example, it can transmit a signal indicating whether the contactor is switched on or be used for electrical interlocking.

What does 1NO+1NC mean?
1NO means one normally open contact that closes when the device is actuated. 1NC means one normally closed contact that opens when the device is actuated. This combination allows two different control functions to be performed at the same time.

Is this contact suitable for all contactors?
No. This model is designed for compatible SIEMENS 3RH and 3RT series contactors / contactor relays. Before ordering, it is recommended to check whether your contactor model supports the 3RH2911-1LA11 accessory.

Where is this auxiliary contact mounted?
The contact is mounted on the front part of the contactor, and the wires are connected from the top through screw terminals.