Siemens 3RT2015-1BB41 — AC-3 Contactor Buying Guide

By Abdullah Zahid
13 min read
Siemens 3RT2015-1BB41 three-pole AC-3 power contactor S00 frame 24V DC coil for motor starter panel

Siemens 3RT2015-1BB41 Power Contactor: 7A AC-3 Motor Control Specifications and Selection Guide

When you are specifying a compact motor starter or replacing a failed contactor in a feeder panel, the Siemens 3RT2015-1BB41 power contactor is a bottom-of-funnel decision — you already know the SIRIUS family, and now you need to confirm the 7 A AC-3 rating at 400 V, the 24 V DC coil, the single 1 NO auxiliary contact, and the S00 frame all line up with your panel design before placing the order. This is a three-pole electromagnetic contactor rated for 3 kW motor loads at 400 V, built on the smallest SIRIUS frame size, and designed for daily start-stop motor duty in industrial control panels worldwide.

If you have already confirmed this is the right part, check current pricing and availability at LeadTime.ca — ships worldwide.

Who Should Buy the 3RT2015-1BB41 — and Who Shouldn't

This contactor is the correct choice when all five of the following conditions are true for your application:

  • Your motor load does not exceed 3 kW at 400 V (or 1.5 kW at 230 V) under AC-3 motor duty — the 7 A rating is the hard ceiling
  • Your control circuit runs on 24 V DC — this coil is not interchangeable with 24 V AC or any other voltage variant
  • Your panel wiring uses screw terminals — this is not the spring-terminal variant
  • A single 1 NO auxiliary contact is sufficient for your status feedback or interlock logic
  • Your panel layout accommodates the S00 frame and you are mounting to a standard 35 mm DIN rail or panel back-plate

If your motor exceeds 3 kW, your coil voltage is 110 V AC or 230 V AC, or you need more than one auxiliary contact, this is not the right catalog number — the 3RT2025 (16 A, S2 frame) or an alternate coil voltage variant within the 3RT2015 family is the correct path.

On this page:

What the 3RT2015-1BB41 Actually Does in a Motor Control Circuit

The Siemens 3RT2015-1BB41 is a three-pole electromagnetic power contactor classified under the SIRIUS product family. Its job is simple and mechanical: when a 24 V DC signal energizes the coil, the armature pulls in and closes three main contacts simultaneously, connecting the motor supply lines to the motor windings. When the coil is de-energized, a return spring opens the contacts and breaks the circuit. It does this under AC-3 utilization category duty, which is defined for squirrel-cage induction motors with switching during running — the category that covers the vast majority of direct-on-line and star-delta motor starter applications.

The product is rated 7 A AC-3 at 400 V, which corresponds to a 3 kW motor load at that voltage. At 230 V, the AC-3 rating supports 1.5 kW. At 690 V, the same contactor supports 4 kW because the reduced operating current at higher voltage brings the kilowatt capacity up despite the lower current figure of 4.9 A. The AC-1 non-inductive rating is 18 A at 400 V, which confirms the electrical robustness of the contacts for resistive loads, but AC-3 is the binding specification for any motor application.

The 1 NO auxiliary contact built into the base unit is a Form A signaling contact used for motor running status feedback to a PLC input, operator panel indicator, or interlock circuit. It is not a power contact — it handles the low-current relay logic side of the circuit. The coil draws 166.7 mA at 24 V DC with a power consumption of 4 W and a coil resistance of 144 ohms. That low coil burden is one practical reason the 24 V DC SIRIUS contactors are so common in PLC-controlled panels: multiple contactors can be driven from a single 24 V supply without overloading the control power budget.

Typical System Architecture for SIRIUS S00 Contactor Deployment

The 3RT2015-1BB41 sits at the switching layer between the control system and the motor load — it receives a logic-level command and closes a three-phase power circuit. Here is how the signal and power chain typically looks:

  • PLC or control relay outputs a 24 V DC signal to the contactor coil terminals A1 and A2
  • The 3RT2015-1BB41 coil energizes, pulling in the armature and closing the three main contacts (L1-T1, L2-T2, L3-T3)
  • Three-phase motor supply voltage is routed through the closed main contacts to the motor terminals
  • A thermal overload relay (3RU series) installed downstream of the contactor monitors motor current and trips the control circuit if overload persists
  • The 1 NO auxiliary contact (terminals 13-14) returns a confirmation signal to the PLC input or pilot light, confirming the contactor is closed and the motor circuit is energized

Where Engineers Deploy the 3RT2015-1BB41

Direct-on-line (DOL) motor starters are the most common application for this contactor. Whenever a small pump, fan, conveyor drive, or compressor needs to be switched on and off from a single operator command or PLC output, the 3RT2015-1BB41 is a standard choice for motors up to 3 kW at 400 V. The AC-3 rating ensures it can handle the inrush current during motor starting without accelerated contact erosion.

HVAC systems with multiple independently controlled air handlers, zone fans, or chiller pumps frequently use S00-frame contactors like the 3RT2015-1BB41 in modular feeder panels. The compact footprint allows multiple motor starters to be built into a narrow enclosure, which is critical when building mechanical rooms have space constraints.

In food and beverage processing facilities, the 24 V DC coil is standard because plant-wide control power is typically distributed at 24 V DC from centralized power supplies. The 3RT2015-1BB41 integrates directly into these plants without requiring separate control transformers for each starter.

Water treatment pump stations and material handling conveyors operating at frequent start-stop duty cycles also rely on AC-3 rated contactors in this size range. The rated mechanical and electrical endurance for AC-3 cycling — approximately 200,000 switching operations — means at a typical rate of 5 to 10 motor starts per day, the contactor delivers decades of reliable service before contact wear becomes a maintenance concern.

Application Typical Deployment
DOL motor starter Three-phase induction motor up to 3 kW at 400 V, switched by PLC output or pushbutton
HVAC zone fan control Modular feeder panel with multiple S00 starters, 24 V DC control from BMS
Pump station AC-3 frequent start-stop duty, paired with 3RU thermal overload relay
Conveyor and material handling Reversing or DOL starter with mechanical interlock between two contactors
Food and beverage processing Plant-wide 24 V DC control standard, compact S00 frame for hygiene-zone panel design
Star-delta soft-start Used as main or delta contactor in reduced inrush starter configurations

Key Electrical Specifications at a Glance

Specification Value
Utilization category AC-3e / AC-3
AC-3 current rating 7 A
Motor power at 400 V (AC-3) 3 kW
Motor power at 230 V (AC-3) 1.5 kW
AC-1 current rating at 400 V 18 A
Coil voltage 24 V DC
Coil power consumption 4 W
Coil resistance 144 ohms
Auxiliary contacts 1 NO
Frame size / terminal type S00 / Screw terminal

Full technical specifications are available on the product page at LeadTime.ca.

3RT2015-1BB41 vs. 3RT2025 vs. 3RT2035: Which Frame Do You Actually Need?

Model Frame Size AC-3 Current at 400 V Motor Power at 400 V Typical Application
3RT2015-1BB41 S00 7 A 3 kW Small motors, pumps, fans, conveyors
3RT2025 S2 16 A 5.5 kW Medium motors, 5–7 kW range, larger starters
3RT2035 S3 38 A 15 kW Large motor starters, main feeder contactors

If your motor nameplate reads 3 kW or below at 400 V and your control voltage is 24 V DC, the 3RT2015-1BB41 is the correct and most cost-effective choice — check current availability at LeadTime.ca.

Expert Verdict: Honest Assessment for Panel Builders and Procurement

The Siemens 3RT2015-1BB41 does one thing exceptionally well: it provides reliable, long-life switching for small three-phase motor loads in a form factor that fits almost anywhere. The S00 frame is the most compact in the SIRIUS line, the 24 V DC coil integrates directly with modern PLC I/O without auxiliary relays, and the 7 A AC-3 rating covers the overwhelming majority of small motor applications in HVAC, pumping, and conveyor systems. With approximately 200,000 AC-3 switching cycles of rated endurance and an ambient operating range of -10°C to +55°C, this contactor is not a compromise — it is the right tool for small motor duty.

Where it has real limits: the 3 kW ceiling at 400 V is firm. If your motor is 4 kW or larger, do not attempt to stretch the rating — the 3RT2025 is the correct next step. The single 1 NO auxiliary contact is also a genuine constraint; if your interlock logic requires an NC contact or multiple NO contacts, you will need to budget for an external contact block or select a variant with the required contact configuration. The coil voltage is also non-negotiable — a 24 V AC source will damage this coil, and there is no field-adjustable coil inside the unit. And critically: this contactor provides no overload protection on its own. A thermal overload relay such as the 3RU2116 must be specified alongside it for a complete, code-compliant motor starter.

From a procurement standpoint, Siemens SIRIUS S00 contactors are among the most consistently stocked items in industrial distribution worldwide. Availability at major distributors is typically 1 to 2 weeks, and volume pricing for quantities of five or more units reduces per-unit cost meaningfully. LeadTime.ca maintains stock and ships worldwide — no regional restrictions. If you are building a panel with six identical motor starters, contact the team for volume pricing before finalizing your BOM. If this matches your system requirements, view current stock and pricing at LeadTime.ca.

For volume pricing or to confirm lead time before committing to a build, contact the LeadTime.ca team directly — we ship worldwide.

Wiring and Installation Overview

  • Power circuit connections use screw terminals labeled L1, L2, L3 (supply) and T1, T2, T3 (motor) — verify cable gauge matches motor current rating and torque the terminals per Siemens installation documentation
  • Coil terminals A1 and A2 accept 24 V DC from a PLC output, relay contact, or pushbutton station — confirm the source is 24 V DC (not 24 V AC) before connection to avoid coil damage
  • The 1 NO auxiliary contact is wired at terminals 13 and 14 and returns a motor-running confirmation signal to the control circuit — wire gauge of 1.5 to 2.5 mm is appropriate for this pilot circuit
  • Mount on a standard 35 mm DIN rail or bolt to a panel back-plate in the standard upright orientation — 90-degree horizontal mounting is supported if panel layout requires it
  • If the contactor will share a control supply with PLC outputs or soft-starters, fit a surge suppressor across the coil terminals to protect sensitive electronics from switching transients

Compatible Modules and System Expansion

The 3RT2015-1BB41 is designed to work within the broader SIRIUS ecosystem. The following accessories and companion devices are relevant to a complete motor starter assembly:

  • 3RU2116 thermal overload relay — must be specified alongside the contactor to provide motor overload and locked-rotor protection; the contactor alone does not trip on overcurrent
  • External contact blocks — can be stacked onto the contactor body to add NC contacts or additional NO contacts beyond the built-in 1 NO, adding mounting height but preserving the S00 frame footprint
  • 3RT2926-2A surge suppressor module — mounts on the coil terminals to clamp switching transients when PLC outputs or soft-starters are switching the coil circuit
  • Mechanical interlock lever — attaches between two adjacent 3RT2015 contactors to physically prevent simultaneous closure in forward-reverse motor control applications

Wrong-Part Prevention Checklist Before You Order

Before finalizing your order for the Siemens 3RT2015-1BB41, verify every item on this checklist to prevent a costly mis-shipment or panel rework:

  1. Verify motor nameplate kW does not exceed 3 kW at 400 V AC-3 rating
  2. Confirm control circuit voltage is 24 V DC (not 24 V AC or 110 V)
  3. Confirm screw terminal type matches panel terminal strips (not spring terminal variant)
  4. Verify single 1 NO contact is sufficient (not 2 NO or NC configuration)
  5. Confirm size S00 frame fits panel cutout and mounting space
  6. Check that AC-3 utilization category matches application (not AC-4, AC-5 or AC-6a)
  7. Ensure external overload relay 3RU will be added for motor protection (contactor alone has no overload function)
  8. Verify IEC 60947-4 compliance requirement is met (standard for this product)

If any item on this checklist raises a question, contact the LeadTime.ca team before ordering — our technical team can confirm the correct catalog number for your application, or point you to the right alternate variant if the 3RT2015-1BB41 is not the correct fit.

Frequently Asked Questions

Can the 3RT2015-1BB41 be used for AC-4 inching or plugging duty?

No. The 3RT2015-1BB41 is rated for AC-3 utilization category, which covers switching of squirrel-cage motors during running. AC-4 duty — which includes plugging and inching where the motor is switched against full inrush — imposes significantly higher contact stress. If your application involves frequent inching or plugging, you must select a contactor rated for AC-4 duty at your operating current, which typically means a larger frame and higher-rated contacts than the 7 A AC-3 rating here allows.

What happens if I connect 24 V AC instead of 24 V DC to the coil?

Connecting 24 V AC to a 24 V DC coil will likely burn out the coil. DC coils are wound with resistance optimized for steady DC current draw — in this case 166.7 mA at 4 W. An AC source applies alternating current through the coil, which behaves differently due to the absence of rectification inside the unit. The result is typically rapid coil overheating and failure. Always measure the control supply with a voltmeter and confirm polarity and AC/DC type before energizing the coil.

Does the 3RT2015-1BB41 include motor overload protection?

No. The contactor switches the motor circuit but provides no thermal or electronic overload protection. Motor protection against sustained overcurrent, phase loss, or locked-rotor conditions requires a separate thermal overload relay — the 3RU2116 or an equivalent SIRIUS overload relay wired in series downstream of the contactor main contacts. Without an overload relay, this starter assembly is incomplete and the motor is unprotected against thermal damage. This is a common ordering omission and is the most important item on the wrong-part prevention checklist.

How do I add a second auxiliary contact to this contactor?

The base 3RT2015-1BB41 includes one 1 NO auxiliary contact. If your interlock or feedback logic requires additional contacts — such as an NC contact for a stop circuit or a second NO for a second PLC input — you have two options: add an external contact block to the contactor body, which stacks on and increases mounting height, or select a larger variant with the required built-in contact configuration. The choice depends on panel space and whether the additional contact must be mechanically linked to the main contactor actuation.

What is the minimum holding voltage for the 24 V DC coil?

The coil requires a minimum of approximately 85% of rated coil voltage to remain energized. For a 24 V DC nominal coil, that is approximately 20.4 V DC. If your control bus voltage sags below this threshold — for example, under a heavy simultaneous load on the 24 V supply — the contactor will drop out and the motor circuit will open. If voltage dips are a known issue in your panel, verify the 24 V power supply is adequately sized for the total control load, and consider adding capacitance on the control bus to stabilize voltage during transient events.

Is the Siemens 3RT2015-1BB41 approved for use in North America?

Yes. The 3RT2015-1BB41 conforms to IEC 60947-4-1 for low-voltage AC contactors and carries UL listing for the North American market. The voltage ratings and 50/60 Hz frequency accommodation make it suitable for deployment in both 400 V European-standard systems and 460 V North American three-phase systems. RoHS compliance is confirmed for the product.

Why Order From LeadTime.ca

  • LeadTime.ca ships worldwide — no regional restrictions on sourcing or quoting
  • Direct access to Siemens SIRIUS inventory for both single-unit orders and volume BOM fulfillment
  • Technical team can confirm coil voltage variant, frame size, and auxiliary contact configuration before order placement — reducing mis-shipment risk
  • Volume pricing available for panel builders and OEMs ordering five or more units of the same catalog number
  • Fast response on quote requests for time-sensitive panel builds and MCC projects

At-a-Glance Summary

  • Siemens 3RT2015-1BB41 is a three-pole AC-3e/AC-3 power contactor rated 7 A at 400 V, equal to 3 kW motor load capacity
  • At 230 V the AC-3 motor rating is 1.5 kW; at 690 V the rating rises to 4 kW with a reduced operating current of 4.9 A
  • Coil voltage is 24 V DC with a power consumption of 4 W, coil resistance of 144 ohms, and draw of 166.7 mA
  • Built-in auxiliary contacts: 1 NO (Form A), terminals 13 and 14, for status feedback and interlock signaling
  • Frame size S00 — smallest SIRIUS contactor frame — with screw terminal connection type and 35 mm DIN rail mounting
  • AC-1 non-inductive current rating is 18 A at 400 V
  • Ambient operating range -10°C to +55°C; altitude up to 3,000 m without derating
  • Rated for approximately 200,000 AC-3 switching cycles of electrical endurance
  • Compliant with IEC 60947-4-1; UL listed for North American deployment; RoHS compliant
  • No overload protection built in — must be paired with a 3RU series thermal overload relay for a complete motor starter
  • Next frame up is the 3RT2025 at 16 A AC-3 and 5.5 kW at 400 V for motors exceeding the 3 kW threshold