Siemens 3RT20181BB41 Contactors
Specs: 3RT20181BB41
| Spec | Value |
|---|---|
| Coil Voltage | 24 VDC |
| Contact Rating | 16 A |
| Contact Form | 3PST-NO (3 Form A) |
| Coil Power | 4 W |
| Coil Current | 166.7 mA |
| Coil Resistance | 144 Ω |
| Must Operate Voltage | 19.2 VDC |
| Mounting | Chassis Mount, DIN Rail |
| Encapsulation | Bulk |
The 3RT2018 series uses a size S00 frame. The 24 VDC coil draws 4 W steady-state and requires 19.2 VDC minimum to pull in, giving an 80% must-operate margin against nominal. Bulk packaging ships the contactor without a separate box or terminal cover; those accessories are ordered separately.
Compare: Seed vs Alternates
The reader must qualify all alternates independently against application requirements.
| Spec | 3RT20181BB41 (seed) | 3RT20181BB42 | 3RT20181BB443MA0 | 3RT20181BW41 |
|---|---|---|---|---|
| Coil Voltage | 24 VDC | 24 VDC | 24 VDC | 48 VDC |
| Contact Rating | 16 A | 16 A | 16 A | 16 A |
| Contact Form | 3PST-NO (1 NO) | 3PST-NO (1 NC) | 3PST-NO (2 NO + 2 NC) | 3PST-NO (1 NO) |
| Encapsulation | Bulk | Bulk | Bulk | Box |
| Similarity | — | 1.0 | 1.0 | 1.0 |
- 3RT20181BB42 shares the 24 VDC coil and bulk packaging but provides one NC main contact instead of NO—useful for motor停止 circuits rather than motor-start.
- 3RT20181BB443MA0 adds two NC auxiliary contacts to the standard one-NO configuration, increasing I/O density for control schemes requiring segregated status signals.
- 3RT20181BW41 uses the same 16 A, 4 W coil architecture but at 48 VDC, requiring a higher coil-supply voltage and consuming roughly double the must-operate voltage margin (38.4 VDC minimum) for compatibility with 48 V systems.