Siemens 3RT20261AG20 Size S0 Contactor
Parameter Summary
| Specification | Value |
|---|---|
| Contact Rating | 25 A |
| Coil Voltage | 110 VAC |
| Contact Form | 3PST-NO (3 Form A) |
| Auxiliary Contacts | 1NO/1NC |
| Mounting | Chassis Mount, DIN Rail |
| Must Operate Voltage | 93.5 VAC |
| Coil Power | 81 VA |
| Operate Time | 40 ms |
| Operating Temperature | 25°C ~ 60°C |
| Encapsulation | Bulk |
The 3RT20261AG20 is a Siemens Size S0 (45 mm width) contactor in the 3RT2026 series. The "AG" in the MPN encodes the 110VAC coil class and 1NO/1NC auxiliary contact configuration. Bulk packaging is noted for the seed record.
Application Context
This contactor is sized for motor branch switching and is suitable for direct-on-line (DOL) starting of three-phase motors where the auxiliary contact block provides feedback or interlock paths. The 25 A contact rating places it at the lower end of the S0 frame; coordination with upstream short-circuit protection (MCCB or fuse) follows standard panel practice for motor branch circuits.
DIN rail mounting accommodates standard EN 60715 rail. Bulk packaging typically reflects distributor inventory rather than a distinct unit packaging configuration.
Catalog Comparison
The 3RT20261AG20 shares its base series (3RT2026) and Size S0 frame with multiple coil voltage variants and contact configurations.
| MPN | Coil Voltage | Contact Form | Coil Power | Must Operate | Similarity |
|---|---|---|---|---|---|
| 3RT20261AG20 (seed) | 110 VAC | 3PST-NO + 1NO/1NC aux | 81 VA | 93.5 VAC | — |
| 3RT20261AG24 | 110 VAC | 3PST-NO + 2NO/2NC aux | 79 VA | 93.5 VAC | 1.0 |
| 3RT20261AG60 | 100 VAC | 3PST-NO + 1NO/1NC aux | 79 VA | 93.5 VAC | 1.0 |
| 3RT20261AC20 | 24 VAC | 3PST-NO + 1NO/1NC aux | 81 VA | 20.4 VAC | 1.0 |
Why the Alternates Are Catalog Peers
- 3RT20261AG24: Same coil voltage and base series; doubles the auxiliary contact count to 2NO/2NC. Both bulk/box encapsulation is noted in records. The additional auxiliaries support more complex interlock or indication circuits without adding a separate aux block.
- 3RT20261AG60: Same auxiliary configuration and 1.0 similarity; the 100 VAC coil rating diverges from the seed's 110 VAC designation, which may affect pick-up performance in some supply regions.
- 3RT20261AC20: Same 1NO/1NC aux and bulk packaging; the 24 VAC coil targets control circuits at lower control voltage (e.g., PLC-output-driven coils or safety circuits).
No in-catalog alternate has been OEM-endorsed as interchangeable; selection requires the user's own review of coil voltage match and auxiliary contact requirements.
Selection Considerations
- Coil voltage match: The must-operate voltage of 93.5 VAC defines the minimum control voltage needed for guaranteed pull-in at rated load. Verify the actual control circuit nominal voltage and tolerance band against this value.
- Auxiliary contact count: The seed provides one NO and one NC auxiliary. If additional status feedback or interlock paths are needed, the 2NO/2NC variant (3RT20261AG24) avoids a separate aux block addition.
- Coil power: At 81 VA inrush (seed), the holding power and control transformer sizing follow from this value. The 79 VA coil power variants may reduce holding burden slightly.
- Operating temperature range: The 25°C to 60°C upper limit is moderate; panel thermal conditions above ambient should be evaluated for enclosed cabinet arrangements.
- Mounting: Chassis and DIN rail options are listed; both share the same S0 cutout envelope.