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Siemens 3RH2911-1HA11 Specs: 1NO+1NC Auxiliary Contact Block Guide
The Siemens 3RH2911-1HA11 is a SIRIUS front-mounted auxiliary contact block featuring one normally open (1 NO) and one normally closed (1 NC) instantaneous contact. It uses screw terminals and is designed for compatible Siemens 3RT2 power contactors and 3RH2 contactor relays. The module adds an additional switching path for control, interlocking, and status feedback circuits without replacing the main contactor.
Siemens 3RH2911-1HA11 Technical Specifications
The 3RH2911-1HA11 belongs to the Siemens SIRIUS auxiliary switch range. Its compact front-mounted design allows engineers to expand an existing contactor’s auxiliary contact configuration.
| Specification | Details |
|---|---|
| Manufacturer | Siemens |
| Product family | SIRIUS 3RH29 |
| Model number | 3RH2911-1HA11 |
| Product type | Front-mounted auxiliary contact block |
| Contact configuration | 1 NO + 1 NC |
| Contact operation | Instantaneous |
| Mounting method | Front snap-on mounting |
| Terminal connection | Screw terminals |
| Compatible product families | Specified 3RT2 contactors and 3RH2 contactor relays |
| Rated insulation voltage | 690 V |
| Rated impulse withstand voltage | 6 kV |
| AC-12 operational current at 24 V | 10 A |
| AC-12 operational current at 230 V | 10 A |
| AC-15 operational current at 230 V | 6 A |
| AC-15 operational current at 400 V | 3 A |
| AC-15 operational current at 690 V | 1 A |
| DC-13 operational current at 24 V | 6 A |
| DC-13 operational current at 110 V | 1 A |
| DC-13 operational current at 220 V | 0.3 A |
| Front protection rating | IP20 |
| Operating temperature | -25°C to +60°C |
| Storage temperature | -55°C to +80°C |
| Mechanical service life | 10 million operating cycles, typical |
| Electrical endurance at AC-15, 230 V | 200,000 operating cycles, typical |
| Net weight | Approximately 45–47 g |
Source: Siemens official 3RH2911-1HA11 datasheet and Siemens Industry Mall product information.
How Does the 1NO+1NC Auxiliary Contact Block Work?
The 3RH2911-1HA11 operates mechanically through the contactor to which it is attached. When the contactor changes its operating state, the auxiliary contacts change state accordingly.
Its contact arrangement provides two different signal conditions:
- Normally open (NO): The contact is open when the contactor is de-energized and closes when the contactor operates.
- Normally closed (NC): The contact is closed when the contactor is de-energized and opens when the contactor operates.
This combination is useful when a control circuit needs both an operating signal and a complementary switching signal from the same contactor.
Typical terminal arrangement
| Terminal designation | Contact type | Normal state |
|---|---|---|
| 13–14 | Normally open | Open |
| 21–22 | Normally closed | Closed |
Always verify the actual terminal markings and wiring diagram on the device before connecting control circuits.
Where Is the 3RH2911-1HA11 Used?
The main purpose of this auxiliary switch is to expand the control functionality of an existing contactor without changing its main power-switching arrangement.
Common applications include:
- PLC status feedback: The NO contact can provide a contactor operating signal to a PLC digital input.
- Electrical interlocking: The NC contact can be incorporated into a control circuit that prevents conflicting operating commands.
- Motor starter monitoring: Auxiliary contacts can communicate contactor operating conditions to monitoring circuits.
- Machine control: The additional switching path supports sequencing and equipment status indication.
For example, a motor starter may use the NO contact to indicate that the contactor has been commanded to operate, while the NC contact participates in a separate interlocking circuit.
These contacts indicate the auxiliary mechanism’s position. They should not automatically be treated as proof that the motor is running or that the main power contacts are electrically healthy.
Understanding AC-15 and DC-13 Contact Ratings
The electrical rating of an auxiliary contact depends on the type of load being switched. The 3RH2911-1HA11 has different operational current limits under AC-12, AC-15, and DC-13 utilization categories.
| Utilization category | Voltage | Operational current |
|---|---|---|
| AC-12 | 24 V | 10 A |
| AC-12 | 230 V | 10 A |
| AC-15 | 230 V | 6 A |
| AC-15 | 400 V | 3 A |
| AC-15 | 690 V | 1 A |
| DC-13 | 24 V | 6 A |
| DC-13 | 110 V | 1 A |
| DC-13 | 220 V | 0.3 A |
AC-15 is relevant to controlling electromagnetic loads such as contactor coils. DC-13 applies to DC electromagnetic control loads, which have different switching characteristics.
For this reason, the 10 A AC-12 rating should not be used as a universal current rating. Engineers must select the appropriate rating according to the actual load and operating voltage.
Compatibility with Siemens 3RT2 and 3RH2 Products
One important feature of the 3RH2911-1HA11 is its compatibility with specified Siemens SIRIUS 3RT2 power contactors and 3RH2 contactor relays.
The accessory is designed for front snap-on mounting. However, sharing the same SIRIUS product family does not mean that every contactor model accepts the same auxiliary block.
Before installation, verify:
- The complete contactor model number.
- The contactor’s physical size and front mounting interface.
- The auxiliary contact capacity required by the existing circuit.
- The screw-terminal configuration.
- The contactor generation and applicable Siemens compatibility documentation.
For applications involving motor switching, the Siemens 3RT6015-1AN21 power contactor is a related SIRIUS product worth reviewing. Its exact compatibility with this auxiliary switch must be confirmed against the manufacturer’s selection documentation before installation.
Installation and Replacement Considerations
The 3RH2911-1HA11 uses front snap-on mounting and screw terminals. Its installation requires a compatible contactor interface and correct terminal wiring.
During replacement, technicians should check the following:
- Ensure that the contactor is isolated from its electrical supply before installation.
- Confirm that the auxiliary block is designed for the installed contactor.
- Check that the block is securely attached to the contactor front.
- Verify the NO and NC terminal numbering against the wiring diagram.
- Use conductors and tightening procedures specified by Siemens.
- Test the auxiliary contact states during commissioning.
The IP20 rating applies to the front protection of the accessory. It is intended for use inside an appropriate electrical enclosure rather than direct exposure to water or environmental contamination.
What Should Buyers Check Before Ordering?
When sourcing this auxiliary contact block, the complete order number is essential. Several Siemens auxiliary switches have similar appearances but different contact arrangements, mounting designs, and terminal types.
Before requesting a quotation, prepare:
- Complete part number: 3RH2911-1HA11.
- Existing contactor or contactor relay model.
- Required contact arrangement: 1 NO + 1 NC.
- Terminal requirement: screw terminals.
- Purchase quantity and required product condition.
- Delivery destination.
You can explore related components through the Siesource industrial automation product catalogue. For a model-specific sourcing enquiry, provide the complete contactor reference and auxiliary switch requirements through the Siesource contact page.
Frequently Asked Questions
What is Siemens 3RH2911-1HA11 used for?
It is a front-mounted auxiliary contact block used to add one normally open and one normally closed switching contact to compatible Siemens contactors and contactor relays.
Does the 3RH2911-1HA11 use screw terminals?
Yes. This model uses screw terminals for its auxiliary circuit connections.
Can the 3RH2911-1HA11 be used with Siemens 3RT2 contactors?
Yes, it is specified for compatible 3RT2 contactors and 3RH2 contactor relays. The exact contactor reference and mounting arrangement should still be checked.
What is the AC-15 rating at 230 V?
The specified AC-15 operational current is 6 A at 230 V. Other voltages and utilization categories have different ratings.
How long is the mechanical service life?
Siemens lists a typical mechanical service life of 10 million operating cycles. Actual service life depends on operating conditions and installation requirements.
Conclusion
The Siemens 3RH2911-1HA11 is a compact SIRIUS auxiliary contact block with one NO and one NC instantaneous contact, screw terminals, and front snap-on mounting. It is designed to expand the control and monitoring functions of compatible 3RT2 contactors and 3RH2 contactor relays. Before purchasing or replacing it, verify the contactor model, mounting interface, terminal arrangement, and electrical utilization ratings.