Siemens 3rt2027-1ap00

By Abdullah Zahid
13 min read
Siemens 3RT2027-1AP00 SIRIUS S0 power contactor 32A 230V AC coil for three-phase motor control

Siemens 3RT2027-1AP00 Power Contactor: Complete Specs, Selection Guide, and Pricing for AC-3 Motor Control

Controls engineers and panel builders searching for the Siemens 3RT2027-1AP00 are typically at the final validation stage — they have a motor to switch, a control cabinet to fit, and a 230 V AC control circuit already designed. This is a 32 A, 15 kW (at 400 V) three-pole power contactor from the SIRIUS product family, built for AC-3 and AC-3e induction motor duty, with an integrated 1 NO + 1 NC auxiliary contact pair and a rated mechanical life of 10 million cycles. The single decision left is whether this exact catalog number fits the load, voltage, and panel requirements — and this guide answers that directly.

If you have already confirmed this is the right part, check current pricing and availability for the Siemens 3RT2027-1AP00 at LeadTime.ca — ships worldwide.

Is the Siemens 3RT2027-1AP00 the Right Contactor for Your Application?

This contactor is the correct choice for engineers switching three-phase AC induction motors and resistive loads where the motor full-load amperage stays within the 32 A AC-3 rating and the control circuit runs at 230 V AC, 50 Hz.

  • Motor full-load amperage (FLA) at AC-3 duty does not exceed 32 A at 400 V or 500 V
  • Connected load power does not exceed 15 kW at 400 V (18.5 kW at 690 V)
  • Control circuit coil supply is confirmed at 230 V AC, 50 Hz — not 24 V DC or 110 V AC
  • Main circuit operating voltage is within the 690 V maximum
  • Application duty is AC-3 or AC-3e (standard motor starting); AC-4 rapid-cycling duty reduces the effective rating to 22 A
  • Panel accommodates S0 size DIN rail or screw terminal mounting

If your motor exceeds 15 kW at 400 V, or if your control circuit runs at 24 V DC, this is not the right part number. The 3RT2028 covers loads up to 30 kW at 400 V, and a separate coil variant (such as the -1AK60 suffix) is required for 24 V DC control circuits.

On this page:

What the 3RT2027-1AP00 Actually Does in a Motor Control Circuit

The Siemens 3RT2027-1AP00 is an electromechanical power contactor from the SIRIUS line. Its job is straightforward: it acts as the remote-controlled switching device between the incoming three-phase power supply and the motor terminals. When 230 V AC is applied to the coil terminals A1 and A2, the magnetic armature pulls in, closing the three main poles simultaneously and completing the power circuit to the motor. Remove coil voltage and the spring-return mechanism opens all three poles in under 20 ms.

What distinguishes the 3RT2027-1AP00 from a basic switching relay is its industrial-grade contact geometry, rated to carry and interrupt 32 A repeatedly under AC-3 inrush conditions — typically five to seven times full-load current during direct-on-line starting — without contact welding or significant erosion. The integrated 1 NO and 1 NC auxiliary contacts at terminals 13/14 and 11/12 respectively give the control system real-time status feedback: whether the contactor has actually closed or opened, which is essential for PLC interlock logic, alarm indication, and safety circuit design.

The S0 frame size keeps the physical footprint compact. At approximately 117 g, it mounts directly to a 35 mm DIN rail or via screw terminals, fitting into standard control panels alongside thermal overload relays and supplementary protectors without requiring a dedicated section of the cabinet.

Typical System Architecture: Where This Contactor Sits in the Signal Chain

The 3RT2027-1AP00 occupies the power switching layer in a motor control circuit, positioned downstream from the branch circuit protection and upstream of the motor terminals.

  • Upstream: Three-phase incoming supply feeds through a circuit breaker or fused disconnect, then through an external thermal overload relay (not integrated — required separately)
  • At the contactor: L1, L2, L3 connect to the main incoming terminals; T1, T2, T3 connect to motor leads U, V, W
  • Control layer: 230 V AC coil supply connects at A1/A2, controlled by a pushbutton station, PLC output relay, or safety relay
  • Feedback layer: Auxiliary contacts 13/14 (NO) and 11/12 (NC) route status signals back to PLC input modules or relay logic circuits
  • Downstream: Motor (induction type, up to 15 kW at 400 V) with motor protection device coordinated to 32 A AC-3 rating

Industries and Applications Where the 3RT2027-1AP00 Is Deployed

The 3RT2027-1AP00 covers the most common industrial motor switching scenario: a standard three-phase induction motor in the 5 kW to 15 kW range running standard start/stop duty. In manufacturing environments, this means machine tool spindle drives, conveyor motors, exhaust fans, and coolant pumps — loads that start and stop dozens of times per shift but do not require reversing or rapid plugging.

In HVAC and utility systems, this contactor is regularly used for compressor staging and pump cycling in water treatment, where the 10 million mechanical cycle life rating provides years of service without maintenance intervention. Food processing facilities use it for mixer motors and conveyors, where the Pollution Degree 3 rating handles the light industrial contamination environment typical of those installations, provided the contactor is mounted in an enclosure appropriate to the area classification.

OEM machine builders specify the 3RT2027-1AP00 in packaged electrical cabinets where the motor rating is fixed at the design stage. The integrated auxiliary contacts eliminate the need for bolt-on contact blocks, reducing BOM complexity and cabinet wiring time. Retrofit applications — replacing a failed contactor in a legacy panel without redesigning the control circuit — are also a primary use case, particularly where the original panel was built around SIRIUS-family components.

Application Typical Deployment
Machine tool motor control DOL starter for spindle or coolant pump motors up to 15 kW, PLC-controlled via output relay
Conveyor drive system Multi-motor line with individual contactors per drive motor, interlock via NC auxiliary contacts
HVAC compressor staging Cyclic on/off control for compressor motor, AC-3 duty, thermal overload relay in series
Water pump station Pump cycling automation, motor run status fed back to SCADA via NO auxiliary contact
Legacy panel retrofit Direct replacement for failed SIRIUS contactor, same S0 footprint, no wiring redesign required
OEM packaged machine cabinet Factory-integrated into motor control center, BOM-specified for 230 V AC control circuits

Purchase-Decision Specs and Variant Comparison

Specification Value
Rated Current AC-3 / AC-3e @ 400 V 32 A
Rated Power AC-3 @ 400 V 15 kW
Rated Power AC-3 @ 690 V 18.5 kW
Rated Current AC-1 @ 400 V 50 A
Coil Voltage 230 V AC, 50 Hz
Maximum Operating Voltage 690 V
Thermal Short-Time Current (10 s) 260 A
Mechanical Life 10,000,000 cycles
Ambient Operating Temperature -25 to +60°C
Integrated Auxiliary Contacts 1 NO (13/14) + 1 NC (11/12)

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

Feature 3RT2027-1AP00 3RT2028 (Larger) 3RT2026 (Smaller)
Size Class S0 S2 S00
Rated Current AC-3 32 A 60 A 9 A
Rated Power @ 400 V 15 kW 30 kW 2.2 kW
Mechanical Life 10M cycles 10M cycles 10M cycles
Coil Voltage Options 230 V AC, 24 V DC 230 V AC, 24 V DC 230 V AC, 24 V DC
Integrated Aux Contacts 1 NO + 1 NC 1 NO + 1 NC 1 NO + 1 NC
Price Tier Mid-range Premium (larger) Budget (smaller)
Best For Motors 5–15 kW Motors 15–30 kW Motors 1–5 kW

If your motor sits firmly in the 5 kW to 15 kW range at 400 V with a 230 V AC control circuit, the 3RT2027-1AP00 is the correct choice and the most cost-effective option in this size bracket — check current stock and pricing at LeadTime.ca.

Expert Verdict: When to Buy This Model and When to Walk Away

The Siemens 3RT2027-1AP00 earns its place on the BOM for controls engineers who need a reliable, proven AC-3 contactor in the 15 kW class without overspecifying. The 10 million mechanical cycle rating is a genuine differentiator at this price point — most industrial control panels running one or two motor starts per minute will never get close to that limit in the operational life of the machine. The integrated 1 NO + 1 NC auxiliary contacts are not a premium feature here; they are standard and they eliminate a separate bolt-on contact block, which matters both for cabinet space and for total BOM cost. For standard DOL motor control at 230 V AC, this is a no-compromise choice.

Where the 3RT2027-1AP00 reaches its limits is equally clear. If the motor nameplate exceeds 15 kW at 400 V, do not attempt to rationalize it as close enough — the 32 A AC-3 rating is a hard ceiling and running above it accelerates contact erosion measurably. Likewise, if your control system uses 24 V DC outputs (common in modern PLC-driven panels), you need a different coil variant; the -1AP00 suffix is specifically and exclusively 230 V AC, 50 Hz. For AC-4 rapid-cycling applications — conveyor reversals, plugging brakes, or processes with more than a few dozen starts per hour — the effective rating drops to 22 A and mechanical life degrades faster; evaluate whether the 3RT2028 provides better lifecycle economics before committing. The contactor also carries no integrated overload protection; a separate thermal or electronic overload relay is mandatory for motor branch circuit compliance.

From a procurement standpoint, the 3RT2027-1AP00 is an established catalog item with predictable sourcing. Typical lead time from Siemens when distributor stock is depleted runs approximately 4 weeks. Stocking distributors can often deliver in 1 to 2 weeks. For volume orders of 10 or more units, volume pricing typically applies — it is worth confirming with the LeadTime.ca team before placing a large production run order. If you are sourcing as a replacement part, always order by full catalog number to avoid receiving a different coil voltage variant. 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

  • Main power circuit: Connect three-phase supply to incoming terminals L1, L2, L3; connect motor leads to outgoing terminals T1, T2, T3 — phase sequence must be verified against motor documentation before energizing
  • Coil circuit: Apply 230 V AC, 50 Hz to terminals A1 and A2; this model does not support DC coil supply — confirm control circuit voltage before wiring
  • Auxiliary contacts: Terminal pair 13/14 (NO) closes when contactor is energized; terminal pair 11/12 (NC) opens when energized — route these to PLC input modules or relay logic for status monitoring
  • External protection: No overload relay or circuit breaker is integrated; a thermal or electronic overload relay rated and set to the motor FLA must be installed in series with the main circuit before commissioning
  • Mounting: DIN rail (35 mm) or direct screw terminal mounting is supported; verify panel space accommodates the S0 frame size and that terminal torque is applied per Siemens installation documentation before energizing

Engineers requiring full wiring diagrams and step-by-step installation procedures should refer to the Siemens SIRIUS 3RT2 installation manual available through siemens.com.

AC-3, AC-3e, and AC-4 Duty: What Changes and Why It Matters for Selection

The duty class designation is one of the most commonly overlooked details when ordering a replacement contactor, and getting it wrong leads to premature contact failure rather than an obvious immediate fault.

AC-3 is the standard duty class for squirrel cage induction motor starting — closing against locked-rotor current and opening at full running current. The 3RT2027-1AP00 is rated 32 A at 400 V in this class, corresponding to 15 kW motor power. AC-3e is an enhanced energy efficiency designation that carries identical current and power ratings at 400 V; the practical difference for most applications is negligible, and the two are interchangeable in standard motor starting circuits. Either designation is appropriate for conveyors, pumps, fans, and compressors running standard start/stop cycles.

AC-4 duty covers reversing, plugging (braking by reverse phase connection), and rapid inching — switching both locked-rotor inrush and running current repeatedly in short intervals. Under AC-4 duty, the 3RT2027-1AP00 rating drops to 22 A at 400 V and 6 kW, with a mechanical life target of approximately 200,000 cycles before contact degradation becomes significant. If your application involves more than occasional inch-and-jog operations, calculate the actual duty cycle and cycle count honestly before selecting this model. Applications requiring true AC-4 duty at powers approaching 15 kW should be evaluated for the 3RT2028 instead.

AC-1 duty — resistive and slightly inductive loads such as heating elements — allows the full 50 A @ 400 V rating, which exceeds the AC-3 capability. This is informational for panel designers who may want to use a single contactor model across both motor and resistive load circuits in the same cabinet.

What Engineers Get Wrong When Ordering This Part

The following checklist covers the most common ordering errors for the Siemens 3RT2027-1AP00. Confirm each point before submitting your purchase order.

  1. Verify motor nameplate FLA (full-load amperage) does not exceed 32 A at AC-3.
  2. Confirm plant supply frequency is 50 Hz and coil voltage is 230 V AC (not 24 V DC or other).
  3. Check that load power at operating voltage (400 V, 500 V, or 690 V) does not exceed 15 kW.
  4. Confirm AC-3 or AC-3e duty is correct; AC-4 duty (rapid on/off switching) reduces rated current to 22 A.
  5. Verify main circuit operating voltage does not exceed 690 V.
  6. Ensure panel mounting method supports DIN rail or screw terminal installation.
  7. Check that control circuit can supply 230 V AC coil voltage without step-down transformer or it must be procured.

If any item on this checklist cannot be confirmed before ordering, contact the LeadTime.ca team to review the application and identify the correct catalog number — we ship worldwide and can confirm coil variants, size alternatives, and current availability.

Frequently Asked Questions

What is the coil voltage of the Siemens 3RT2027-1AP00 and can it be replaced with a 24 V DC variant?

The -1AP00 suffix specifies a 230 V AC, 50 Hz coil. This coil is not field-replaceable with a 24 V DC version — a different catalog number with the appropriate coil suffix (such as -1AK60 for 24 V DC) must be ordered. Always match the suffix to your control circuit voltage before purchasing.

Can the 3RT2027-1AP00 replace a 3RT2026 contactor in an existing panel?

Physically, the 3RT2027-1AP00 (S0 frame) is larger than the 3RT2026 (S00 frame), so a direct panel swap requires verifying that the additional space is available. Electrically, if the 3RT2026 was appropriately rated for a motor under 9 A at AC-3, the 3RT2027-1AP00 will work at that load — it simply provides additional current margin. However, if the original selection was space-optimized, confirm panel dimensions before ordering the larger frame.

What external protection is required when using this contactor for motor control?

The 3RT2027-1AP00 does not include any integrated overload or short-circuit protection. A separate thermal overload relay or electronic overload relay must be installed in series with the main circuit and set to the motor FLA. A branch circuit breaker or fused disconnect upstream is also required. Operating the contactor without overload protection risks undetected motor overheating and eventual insulation failure.

What is the mechanical life of the 3RT2027-1AP00 and does it change with auxiliary contacts?

The base mechanical life is 10,000,000 cycles — this applies to the contactor with the standard integrated 1 NO + 1 NC auxiliary contacts. If electronics-compatible switch blocks are added as accessories, the mechanical life figure reduces to 5,000,000 cycles. For most industrial applications running hundreds of cycles per day, even 5 million cycles represents many years of service.

What happens if the 3RT2027-1AP00 is used in AC-4 rapid-cycling duty without derating?

Under AC-4 duty, the rated current drops to 22 A at 400 V (versus 32 A at AC-3). Using the contactor above its AC-4 current limit in a rapid-cycling application accelerates contact pitting and erosion, leading to increased contact resistance, chattering, and eventual welding. The mechanical life target for AC-4 operation is approximately 200,000 cycles — significantly below the 10 million cycle AC-3 rating. Confirm your actual application duty cycle before selecting this model for inching or plugging applications.

What is the thermal short-time current of the 3RT2027-1AP00 and why does it matter for direct-on-line starters?

The 3RT2027-1AP00 is rated for a thermal short-time current of 260 A for 10 seconds. This represents the contactor's ability to withstand the high inrush current during direct-on-line motor starting — typically five to seven times motor FLA — for the duration it takes the upstream circuit breaker to clear a fault. For standard NEMA Design B induction motors up to 15 kW, this rating is not typically a limiting factor. Unusual motor designs with extremely high locked-rotor current should be verified against this figure before specifying a DOL starter.

Why Order the 3RT2027-1AP00 from LeadTime.ca

  • Global shipping: LeadTime.ca ships the Siemens 3RT2027-1AP00 worldwide — no regional restrictions
  • Hard-to-find sourcing: When local distributor stock is depleted and standard Siemens lead times apply, LeadTime.ca works to locate available inventory across its supplier network
  • Volume pricing: Orders of 10 or more units qualify for volume pricing consideration — contact the team before placing large BOM orders
  • Fast response: Technical and procurement questions answered by a team that understands industrial automation and controls applications
  • Genuine parts: LeadTime.ca sources factory-authentic Siemens components with full warranty — no grey-market risk

At-a-Glance Summary

  • Catalog number: Siemens 3RT2027-1AP00 — 3-pole power contactor, SIRIUS family, S0 frame size
  • Rated current: 32 A at AC-3 / AC-3e, 400 V; drops to 22 A under AC-4 rapid-cycling duty
  • Rated motor power: 15 kW at 400 V; 18.5 kW at 690 V
  • Coil voltage: 230 V AC, 50 Hz — this suffix (-1AP00) does not support 24 V DC or other voltages
  • Maximum main circuit voltage: 690 V
  • Thermal short-time current: 260 A for 10 seconds
  • Mechanical life: 10,000,000 cycles (standard); 5,000,000 cycles with electronics-compatible switch blocks
  • Integrated auxiliary contacts: 1 NO at terminals 13/14 and 1 NC at terminals 11/12
  • Operating temperature: -25 to +60°C; storage to -55 to +80°C
  • Protection class: IP20 (front and terminals); Pollution Degree 3
  • Weight: approximately 117 g; mounts on 35 mm DIN rail or screw terminals
  • No integrated overload protection — external thermal or electronic overload relay required
  • Typical lead time: 1–2 weeks from stocking distributors; approximately 4 weeks from Siemens factory