Siemens 3RT20171BB421AA0 S00 Contactor
Engineering Verification Checklist
- Control voltage matches 24 VDC coil specification
- Required pick-up voltage 19.2 VDC is achievable at the coil terminations under load
- 12 A main contact rating meets motor branch coordination requirements for the intended load
- Auxiliary contact configuration (1 NC) satisfies status-feedback or interlock needs
- DIN rail or chassis mounting provisions are available in the enclosure
- Operating temperature range 25°C to 60°C is compatible with the intended environment
- Operate time of 100 ms is acceptable for the sequence timing in the control scheme
- Chassis/DIN rail mounting style accommodates the physical layout of the panel
Overview
The 3RT20171BB421AA0 is an S00-size electromechanical contactor in the Siemens 3RT2 family, rated for 12 A per pole with a 24 VDC coil. It mounts to chassis or DIN rail and carries a single NC auxiliary contact. The contactor sits in the output stage of a motor starter or control circuit, switching the three main poles to energize AC loads from a DC control architecture.
Key Specifications
| Parameter | Value |
|---|---|
| Base Product Number | 3RT2017 |
| Coil Voltage | 24 VDC |
| Coil Power | 4 W |
| Coil Current | 166.7 mA (from catalog record) |
| Must Operate Voltage | 19.2 VDC |
| Contact Form | 3PST-NO (3 Form A) |
| Contact Rating | 12 A |
| Operate Time | 100 ms |
| Encapsulation | Box |
| Mounting | Chassis Mount, DIN Rail |
| Features | Auxiliary Contacts |
| Operating Temperature | 25°C ~ 60°C |
Similar Catalog Parts
Side-by-side screening requires the reader's own qualification against their application.
| Parameter | 3RT20171BB421AA0 | 3RT20171BB411AA0 | 3RT20171BB443MA0 |
|---|---|---|---|
| Coil Voltage | 24VDC | 24VDC | 24VDC |
| Contact Rating | 12 A | 12 A | 12 A |
| Mounting | Chassis/DIN Rail | Chassis/DIN Rail | Chassis/DIN Rail |
| Encapsulation | Box | Box | Bulk |
| Similarity (catalog) | — | 1.0 | 1.0 |
Why 3RT20171BB411AA0 is similar: Shares the same 3RT2017 base, 24 VDC coil, 12 A rating, and chassis/DIN mounting. The auxiliary contact differs—one includes NC where the other includes NO—reflecting the suffix variation in this series of ordering codes.
Why 3RT20171BB443MA0 is similar: Matches on coil voltage, current rating, and mounting style; also carries auxiliary contacts, though in a 2NO/2NC arrangement rather than single NC.
FAQ
What is the must-operate voltage for the 3RT20171BB421AA0? The must-operate voltage is 19.2 VDC. This is approximately 80 % of the rated 24 VDC coil voltage, representing the minimum threshold at which the contactor is guaranteed to close.
Does the 3RT20171BB421AA0 include auxiliary contacts? Yes. The primary includes one normally closed (NC) auxiliary contact. If a normally open (NO) auxiliary configuration is needed, the 3RT20171BB411AA0 shares all other primary parameters but carries an NO auxiliary instead.
What is the operate time for the 3RT20171BB421AA0? The operate time is 100 ms.