Siemens 3RA21254BD260AP6 Direct-On-Line Motor Starter
3RA21254BD260AP6 Family Context
The part number prefix 3RA21 places this device in Siemens' SIRIUS 3RA2 direct-on-line (DOL) motor starter series. The 254 designates the size S0 frame, and the BD suffix encodes the 14–20 A overload setting range combined with 240 VAC coil voltage. The trailing 260AP6 indicates chassis mounting and standard SIRIUS construction. This family covers single-phase AC motor branch protection where DOL starters provide across-the-line starting without variable frequency control.
SIRIUS 3RA21254BD260AP6 Specifications
| Parameter | Value |
|---|---|
| Control / Drive Type | Motor Starter |
| Series | SIRIUS |
| Current - Output | 15.5 A |
| Motor Type | AC Motor |
| Number of Motors | 1 |
| Mounting Type | Chassis Mount |
| Operating Temperature | 20°C ~ 60°C |
| Encapsulation | Box |
| Product Status | Active |
The 15.5 A output rating applies at the load-side switching contacts. The chassis-mount form factor requires a dedicated mounting plane or subpanel inside an enclosure. Operating ambient is specified from 20°C to 60°C, which constrains where the starter may be mounted in heated versus unheated cabinet locations.
Coil and Control Voltage
The part is configured for a 240 VAC coil circuit. Coil voltage selection determines which contactor coil energizes to engage the main poles; this is a key selection dimension when matching the starter to an existing control transformer or voltage source in the panel.
Mounting and Integration
Chassis mounting differs from DIN rail mounting common in compact panel layouts. Designers must provide fixed mechanical support — typically a slotted or clearance-holed bracket or back panel — rather than snapping onto a 35 mm DIN rail. This is typical for heavier starters or when panel builders require high vibration resistance without rail clip creep.
In-Catalog Comparison: SIRIUS DOL Starters
The following table shows how the primary part compares against other SIRIUS starters in the catalog. All require the reader's own qualification; similarity scores do not indicate interchangeability.
| Spec Key | 3RA21254BD260AP6 | 3RA21254BD260AK6 | 3RA21254BD260BB4 |
|---|---|---|---|
| Control / Drive Type | Motor Starter | Motor Starter | Motor Starter |
| Series | SIRIUS | SIRIUS | SIRIUS |
| Current - Output | 15.5 A | 15.5 A | 15.5 A |
| Motor Type | AC Motor | AC Motor | AC Motor |
| Mounting Type | Chassis Mount | Chassis Mount | Chassis Mount |
| Operating Temperature | 20°C ~ 60°C | 20°C ~ 60°C | 20°C ~ 60°C |
| Encapsulation | Box | Box | Box |
| Number of Motors | 1 | 1 | 1 |
| Similarity (0–1) | — | 1.0 | 1.0 |
3RA21254BD260AK6 shares the same S0 frame, 15.5 A output, SIRIUS series, and chassis mounting. The difference is the coil voltage: 120 VAC instead of 240 VAC. This variant suits panels where the control supply is derived from a 120 V transformer or where lower coil voltage reduces hold-in VA.
3RA21254BD260BB4 also shares the same mechanical and output ratings. The suffix indicates a 24 VDC coil variant. DC coil starters eliminate coil dropout on voltage dips and are common in battery-backed or intrinsically safe control circuits, though they require a DC power supply in the panel.
| Spec Key | 3RA21254BA260AP6 | 3RA21254AD260AP6 | 3RA21254ED270AP6 |
|---|---|---|---|
| Control / Drive Type | Motor Starter | Motor Starter | Motor Starter |
| Current - Output | 15.5 A | 15.5 A | 29 A |
| Motor Type | AC Motor | AC Motor | AC Motor |
| Mounting Type | DIN Rail | Chassis Mount | Chassis Mount |
| Operating Temperature | 20°C ~ 60°C | 20°C ~ 60°C | 20°C ~ 60°C |
| Encapsulation | Box | Box | Box |
| Number of Motors | 1 | 1 | 1 |
| Similarity (0–1) | 0.96 | 0.92 | 0.92 |
3RA21254BA260AP6 matches the output rating and motor type but uses DIN Rail mounting instead of chassis mounting. The suffix BA indicates a 240 VAC coil with SCR-type overload configuration. The RoHS status is non-compliant, which may be relevant for new designs in regulated markets.
3RA21254AD260AP6 shares the same chassis mount and 240 VAC coil but covers the 11–16 A overload band. The output rating remains 15.5 A in the catalog record.
3RA21254ED270AP6 represents the next current class up, with a 29 A output rating and a 27–32 A overload band. It shares the same chassis mount and 240 VAC coil configuration but serves larger motors in the S0 frame range.
Engineering Verification Checklist
- Coil voltage matches available control supply (240 VAC here)
- Overload band covers the motor full-load current with appropriate trip class
- Chassis mounting surface and fastening method compatible with panel layout
- Enclosure provides adequate clearance for heat dissipation within 20–60°C ambient range
- Motor count is 1; no multi-motor coordination is required for this starter
- Control circuit coordination with upstream protective device reviewed
- Ground fault and short-circuit protective device rating coordinated with starter let-through
- Compatible with AC motor type specified; not a variable frequency or DC motor application
FAQ
What motor rating does the 3RA21254BD260AP6 cover? The 14–20 A overload setting range in the part number suffix corresponds to typical full-load currents for 5.5–7.5 kW three-phase AC motors at 400 V. The 15.5 A output rating is the switching contact limit.
Can the 3RA21254BD260AP6 be mounted on a DIN rail? The catalog record lists Chassis Mount for this MPN. For DIN Rail mounting, consider the 3RA21254BA260AP6 variant which shares the same 240 VAC coil and output ratings in that form factor.
What coil voltage variants exist for this S0 DOL starter family? The catalog includes 240 VAC (primary part), 120 VAC (3RA21254BD260AK6), and 24 VDC (3RA21254BD260BB4) coil options within this S0 14–20 A current class.