Siemens 3RT20241DB40 Contactors (Electromechanical)
Siemens 3RT S0 Frame — AC3 5.5 kW / DC Coil Contactors
The Siemens 3RT20241DB40 is a size S0 electromechanical contactor in the Sirius 3RT family, rated 12 A with a 24 VDC coil and integrated auxiliary contacts. This page summarizes the on-record specifications and in-catalog peers sharing the 3RT2024 base number.
Siemens 3RT20241DB40: Key Specs at a Glance
| Parameter | Value |
|---|---|
| Base Product Number | 3RT2024 |
| Coil Voltage | 24 VDC |
| Must Operate Voltage | 19.2 VDC |
| Coil Power | 5.9 W |
| Contact Form | 3PST-NO (3 Form A) |
| Contact Rating | 12 A |
| Auxiliary Contacts | 1 NO + 1 NC |
| Mounting | Chassis Mount, DIN Rail |
| Encapsulation | Box |
| Operate Time | 170 ms |
| Operating Temperature | 25°C ~ 60°C |
Selection Trade-Offs for This Frame
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Coil class vs. must-operate voltage. The 19.2 VDC must-operate threshold is specified for the 24 VDC coil. Drop-in coil variants at different voltages shift must-operate values proportionally; verify the driving circuit's typical sag and load dump margins against the specific coil chosen.
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Auxiliary contact count (1NO+1NC) vs. modular expansion. The 3RT20241DB40 ships with one normally open and one normally closed auxiliary contact built in. Siemens offers 3RT2 accessories with 2NO/2NC configurations, but these add width and require separate ordering — evaluate auxiliary needs before specifying a single-unit versus accessory-augmented arrangement.
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DC coil power dissipation. The 5.9 W coil draws approximately 245 mA at nominal 24 VDC. Panel designers should budget for continuous coil heating and confirm that the DC supply can source inrush current during pull-in without voltage collapse, especially in multi-contactor bus arrangements.
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Operating temperature window (25°C ~ 60°C). The published temperature range is narrower than many industrial contactor ranges. For enclosed panels with elevated ambient conditions, thermal derating or forced ventilation may be warranted beyond approximately 50°C enclosure ambient.
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Encapsulation and mounting orientation. Box encapsulation is listed; the 3RT S0 series supports both chassis and DIN-rail mounting. Verify that the selected enclosure layout provides the specified clearances for DIN-rail snap-mount or direct screw-mount based on the physical orientation in the cabinet.
Similar Catalog Parts (Reader Qualification Required)
The table below lists in-catalog peers sharing the 3RT2024 base product number. These are parametric similarities only — none of these rows constitute an interchange approval or an OEM-endorsed substitute. The reader must perform their own suitability review.
| MPN | Coil Voltage | Coil Power | Contact Rating | Contact Form | Must Operate | Operate Time | Similarity |
|---|---|---|---|---|---|---|---|
| 3RT20241DB40 | 24 VDC | 5.9 W | 12 A | 3PST-NO | 19.2 VDC | 170 ms | seed |
| 3RT20241DB443MA0 | 24 VDC | 5.9 W | 12 A | 3PST-NO | 19.2 VDC | 170 ms | 1.00 |
| 3RT20241BB40 | 24 VDC | 5.9 W | 12 A | 3PST-NO | 19.2 VDC | — | 0.92 |
| 3RT20241FB40 | 24 VDC | 5.9 W | 12 A | 3PST-NO | 19.2 VDC | 170 ms | 0.92 |
| 3RT20241KB40 | 24 VDC | 4.5 W | 12 A | 3PST-NO | 16.8 VDC | 170 ms | 0.92 |
Why the top alternate is similar. 3RT20241DB443MA0 shares the same 24 VDC coil voltage, 5.9 W coil power, 12 A contact rating, 3PST-NO contact form, and 170 ms operate time. The similarity score reflects shared series, features, and matching parametric values across the coil and contact sections. The auxiliary contact configuration differs (2NO/2NC vs. 1NO/1NC), which is the primary functional distinction for this seed/alternate pair.
Why 3RT20241KB40 diverges slightly. The 4.5 W coil power and 16.8 VDC must-operate voltage indicate a different coil winding optimized for reduced pick-up current. The contact and mounting specs remain identical, but the electrical interface to the coil drive changes — verify compatibility with the existing DC control circuit before substituting.
FAQ
What auxiliary contact configuration does the 3RT20241DB40 provide? The unit ships with one normally open (NO) and one normally closed (NC) auxiliary contact integrated into the contactor body.
Can the 3RT20241DB40 be mounted on standard 35 mm DIN rail? Yes. The specifications list both chassis mount and DIN rail mounting as supported types.
What is the must-operate voltage for this contactor? The must-operate voltage is 19.2 VDC for the 24 VDC coil class.