Description
The Siemens 3RT20 series are compact, IEC-rated power contactors for motor control and power switching, while the 3RH21 series are matching auxiliary relays and contact blocks. The listed models — 3RT2018-2BB41 (18A / 7.5kW @400V), 3RT2016-2BB41/2BB42 (9A / 4kW), and 3RH2131-1BB40 (4NO), 3RH2140-1BB40 (4NC) — form a complete family for DIN-rail mounted control panels. All feature screw terminals (BB = screw), 24V DC coil (2 = 24V DC coil code for most 3RT20), and are suitable for AC-3 duty motor starting.
Key Features
- Ratings: 3RT2016 = 9A (4kW@400V), 3RT2018 = 18A (7.5kW@400V)
- Coil Voltage: 24V DC (suffix -2 = 24V DC coil, -1 = AC coil — verify per model)
- Terminal Type: Screw terminals (BB41/BB42)
- Mounting: 35mm DIN rail
- Auxiliary Contacts: Up to 4 add-on blocks (3RH21 series) can be snapped onto the front
- Certifications: IEC 60947-4-1, UL 508, CSA, CE
Model Specifications Table
Model | Description | Poles | Rated Current (AC-3) | Coil Voltage | Notes |
|---|---|---|---|---|---|
3RT2018-2BB41 | Power Contactor | 3 NO Main | 18 A (7.5 kW @400V) | 24 V DC | Screw term., front aux. ready |
3RT2018-2BB42 | Power Contactor | 3 NO Main | 18 A (7.5 kW @400V) | 24 V DC | Variant with different aux. contact config |
3RT2018-2BM41 | Power Contactor | 3 NO Main | 18 A (7.5 kW @400V) | 24 V DC | Screw term. (M = spring clamp variant — check) |
3RT2016-2BB41 | Power Contactor | 3 NO Main | 9 A (4.0 kW @400V) | 24 V DC | Compact size |
3RT2016-2BB42 | Power Contactor | 3 NO Main | 9 A (4.0 kW @400V) | 24 V DC | Variant |
3RH2131-1BB40 | Auxiliary Relay | 4 NO | — (6 A rated) | 24 V DC (1=24V DC coil) | 4 Normally Open contacts |
3RH2140-1BB40 | Auxiliary Relay | 4 NC | — (6 A rated) | 24 V DC (1=24V DC coil) | 4 Normally Closed contacts |
⚠️ Coil Confirmation: “2” in 3RT2018-2BB41 = 24V DC coil. AC coil versions use “1” (e.g., 3RT2018-1BB41 = 230V AC 50/60Hz). Always verify coil voltage marking on nameplate before installation.
Technical Data (3RT2018-2BB41 as representative)
Parameter | Value |
|---|---|
Rated Operational Current (AC-3, 400V) | 18 A |
Motor Power (400V AC-3) | 7.5 kW |
Making Capacity (AC-3) | 10 × Ie |
Breaking Capacity (AC-3) | Full breaking at 400V |
Coil Consumption (Pick-up/Hold) | ~ 8 W pick-up / ~ 2.2 W hold (DC coil) |
Mechanical Life | 10 million operations |
Electrical Life (AC-3) | 1.2 million operations |
Auxiliary Contact Add-on | Up to 4 blocks (3RH21xx) — front snap-on |
Terminal Type | Screw (2.5–16 mm² rigid / 1.5–10 mm² flexible) |
Dimensions (W×H×D) | 45 mm × 86 mm × 96 mm (3RT2018) |
Weight | ~0.33 kg |
Standards | IEC 60947-4-1, EN 60947-4-1, UL 508, CSA C22.2 |
Warranty & After-Sales
- Factory new units: 12 months warranty
- Refurbished units: 3-6 months warranty
- Technical support for coil voltage selection & overload relay pairing (3RU11 / 3RV10)
- Auxiliary block (3RH21) configuration assistance
- Wiring diagram & DIN rail spacing guidance
Delivery Time
- Standard delivery: 3-5 working days
- Express shipping available upon request
Why Choose Our Store
- Genuine Siemens low-voltage control products
- Global supply network with competitive pricing
- Expertise in motor control centers & control panel design
- Comprehensive technical documentation (datasheets, dimension drawings)
- Responsive customer service and support
Applications
- Motor starting (pumps, fans, compressors, conveyors)
- Power switching for resistive/heating loads
- Control circuits with auxiliary signaling (via 3RH21 blocks)
- Packaging, textile, woodworking & general machinery
- Retrofit of older 3TF / 3TB contactors
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