Siemens 3RH22621BB40 DC Coil Auxiliary Contactor
Electrical Specifications — 3RH22621BB40
| Parameter | Value |
|---|---|
| Coil Voltage | 24 VDC |
| Coil Power | 4 W |
| Coil Current | 166.7 mA |
| Coil Resistance | 144 Ω |
| Must Operate Voltage | 19.2 VDC |
| Contact Form | 6NO + 2NC (auxiliary) |
| Contact Rating | 10 A |
| Mounting | Chassis Mount, DIN Rail |
| Operating Temperature | 25°C ~ 60°C |
The 3RH22 series uses a DC coil requiring sustained current to hold; pick-up drops below 19.2 VDC, making it unsuitable for systems prone to sag or brownout without hold-in margin analysis.
Contact Arrangement — 3RH22621BB40
The seed unit ships as a 3PST-NO (3 Form A) configuration with auxiliary contacts; the full 8-contact block (6NO + 2NC) is the standard offering in this family series per manufacturer grouping. Bulk packaging implies panel-builder quantity procurement; individual unit pricing is not reflected here.
AC Coil vs DC Coil — In-Family Comparison
The reader must qualify the following alternates against their specific control architecture before any selection decision.
| Spec | 3RH22621BB40 (seed) | 3RH22621AK60 | 3RH22621AP60 | 3RH22622BB40 |
|---|---|---|---|---|
| Coil Voltage | 24 VDC | 120 VAC | 240 VAC | 24 VDC |
| Coil Power | 4 W | 37 VA | 37 VA | 4 W |
| Contact Form | 3 Form A (aux) | 3 Form A (aux) | 6NO/2NC (full block) | 6NO/2NC (full block) |
| Must Operate | 19.2 VDC | 102 VAC | 204 VAC | 19.2 VDC |
| Mount | DIN Rail | DIN Rail | DIN Rail | DIN Rail |
- 3RH22621AK60 and 3RH22621AP60: Same base number with AC coils; 37 VA inrush is a known panel heat-loading factor in enclosed cabinets. The 120 V unit suits North American control transformers; the 240 V unit suits IEC/CE systems.
- 3RH22622BB40: Matches coil voltage and power exactly; full 6NO/2NC contact block versus auxiliary-style arrangement. Operate time extends to 100 ms — relevant for time-critical sequencing.
The DC units (BB40, BW40, BN40, BG40, BD80) share the 4 W steady-state characteristic; voltage scaling affects must-operate thresholds proportionally (e.g., 48 VDC requires 38.4 V pick-up). Panel designers should verify supply regulation under maximum load conditions when using DC coil relays in distributed I/O systems.