Siemens 3RT20171AF01 Electromechanical Contactor
Overview
The 3RT20171AF01 is a Siemens S00-frame three-pole contactor rated 12 A at the main contacts with a 110VAC control coil. It carries "Auxiliary Contacts" as a featured attribute, placing it in the lower end of the Siemens SIRIUS 3RT2 family where size and coil options are encoded in the ordering code. The catalog records a contact form of 3PST-NO (three normally-open poles) and a must-operate voltage of 93.5 VAC. Coil power is listed as 37VA; operate time is 33 ms. The data source does not provide the switching voltage rating, dielectric withstanding voltage, short-circuit coordination class, or the maximum permissive HP/kW rating for motor loads—those values must be confirmed from the official Siemens datasheet before selection proceeds.
Key Parameters
| Parameter | Value (per catalog) |
|---|---|
| Base Product Number | 3RT2017 |
| Contact Rating (Current) | 12 A |
| Contact Form | 3PST-NO (3 Form A) |
| Coil Voltage | 110VAC |
| Coil Power | 37VA |
| Must Operate Voltage | 93.5 VAC |
| Operate Time | 33 ms |
| Mounting Type | Chassis Mount, DIN Rail |
| Encapsulation | Bulk |
| Features | Auxiliary Contacts |
| Operating Temperature | 25°C ~ 60°C |
⚠ Verification required before selection: The catalog fields do not include:
- Maximum switching voltage of the main power contacts (AC-1 / AC-3 rating)
- Dielectric strength between poles and to coil/frame
- Short-circuit coordination category (Type 1 / Type 2 per IEC 60947-4-1)
- Permissible motor load rating in HP or kW
- Terminal torque and wire-size range
These are safety-critical for motor-branch coordination. Do not proceed on electrical ratings until the Siemens SIRIUS 3RT2 datasheet is consulted.
Ordering-Code / Family Context (verify on datasheet)
The 3RT2 series is Siemens' standard industrial contactor family for DIN-rail and panel mounting. Within the "3RT2017" base number the seventh character encodes the coil voltage:
- F → 110VAC (50 Hz) / 120VAC (60 Hz) per Siemens ordering practice.
The last two characters encode the auxiliary contact configuration:
- 01 → 1 NO (normally-open) auxiliary
- 02 → 1 NC (normally-closed) auxiliary
Thus 3RT20171AF01 breaks down as S00 size, 12 A, 110VAC coil, 1 NO auxiliary. The "-1" before "AF" in the full MPN may reflect size-variant encoding not elaborated in the supplied fields; cross-reference against the Siemens SIRIUS configurator to confirm.
Integration / Installation Notes
Mounting is chassis or DIN rail (TH 35-7.5 or TH 35-15 per EN 60715). Specific cutout dimensions, IP protection class, and terminal torque values are not in the supplied fields and must be taken from the datasheet.
The auxiliary contact is useful for coil-seal circuits, status indication, or interlock logic. Operating temperature window is stated as 25°C to 60°C—verify that this suits the enclosure environment in which the contactor will be installed.
Selection / Substitution Notes
The primary difference between listed alternates lies in coil voltage: 110VAC (seed), 24VAC, 42VAC, 48VAC, 230VAC, 240VAC, 380VAC, and 400VAC variants share the same 12A / 3PST-NO main contact rating and S00 frame. Must-operate voltage scales proportionally with coil voltage. Coil power differs between 33VA and 37VA depending on the variant; verify that the upstream control supply can deliver the required inrush VA for the chosen coil.
Substitution is permissible only where the coil voltage, contact rating, and auxiliary-contact type match the circuit requirement. The "identical base product" constraint does not guarantee compatibility with every control topology (e.g., whether the coil is intended for direct drive, transformer-isolated, or PLC-sourced control circuits).
Similar Catalog Parts
| Parameter | 3RT20171AF01 (primary) | 3RT20171AF02 | 3RT20171AP01 | 3RT20171AU01 |
|---|---|---|---|---|
| Coil Voltage | 110VAC | 110VAC | 230VAC | 240VAC |
| Contact Form | 3PST-NO | 3PST-NO | 3PST-NO | 3PST-NO |
| Contact Rating | 12 A | 12 A | 12 A | 12 A |
| Coil Power | 37VA | 33VA | 37VA | 33VA |
| Must Operate Voltage | 93.5 VAC | 93.5 VAC | 195.5 VAC | 204 VAC |
| Operate Time | 33 ms | 35 ms | 33 ms | 35 ms |
| Mounting Type | Chassis Mount, DIN Rail | Chassis Mount, DIN Rail | Chassis Mount, DIN Rail | Chassis Mount, DIN Rail |
| Features | Auxiliary Contacts | Auxiliary Contacts | Auxiliary Contacts | Auxiliary Contacts |
| Encapsulation | Bulk | Box | Bulk | Box |
| Operating Temp | 25°C ~ 60°C | 25°C~60°C | 25°C ~ 60°C | 25°C ~ 60°C |
| Similarity | — | 1.00 | 0.96 | 0.96 |
Why the top alternates are similar
-
3RT20171AF02 shares the same 110VAC coil, 12A / 3PST-NO main contacts, and S00 frame. The only stated difference is the auxiliary contact polarity (NC instead of NO, per the "-02" suffix encoding). Encapsulation differs (Bulk vs. Box), but the electrical interface is functionally equivalent for coil-seal and status-feedback circuits where the relay type (NO vs. NC) must be matched to the logic.
-
3RT20171AP01 matches on frame size, 12A rating, 3PST-NO form, and bulk packaging, but uses a 230VAC coil. Must-operate voltage is 195.5 VAC, roughly double that of the seed—confirm that the control-system nominal voltage aligns with this. Coil power is identical (37VA); operate time remains 33 ms.
-
3RT20171AU01 differs only in coil voltage (240VAC) and encapsulation (Box). Must-operate voltage of 204 VAC reflects the nominal difference; coil power drops to 33VA in the Box variant. Useful where the control transformer secondary is 240VAC rather than 110VAC.
FAQ
Q: Can the 3RT20171AF01 be used for direct-on-line motor starting? A: The catalog does not specify an AC-3 (motor-load) rating or a short-circuit coordination class. These are required to determine suitability for motor starting per IEC 60947-4-1. Verify with the Siemens datasheet before specifying for motor-duty applications.
Q: What is the difference between 3RT20171AF01 and 3RT20171AF02? A: Both have a 110VAC coil and 12A / 3PST-NO main contacts. The suffix "-01" vs. "-02" encodes the auxiliary contact type: 01 = 1 NO, 02 = 1 NC. Choose based on whether the auxiliary contact must open or close when the coil is energized.
Q: Is DIN-rail mounting standard for the S00 frame? A: Yes—the spec lists "Chassis Mount, DIN Rail" as the mounting type. Confirm the specific DIN-rail profile (TH 35-7.5 or TH 35-15) and any required end-stop or retaining clip per the installation manual.