Best Replacement Options for Obsolete Siemens 3TF Contactors

Siemens 3TF contactors are 3-pole World Series motor contactors that Siemens has discontinued, and many are still in service in motor starters and control panels. BRAH Electric makes aftermarket replacements for 24 sizes: 3TF30 through 3TF35 and 3TF40 through 3TF57, with catalogue ratings from 9A to 450A at 600V. The BRAH part number is the Siemens number with a B in front, so a 3TF4622-0AK6 is replaced by a B3TF4622-0AK6.

This guide lists each 3TF size BRAH carries with its catalogue rating, shows how the coil voltage is listed for each part number, and points to the coils, overload relays and arc chutes that go with the same contactors.

Siemens 3TF replacement at a glance

• Order by the full Siemens number on the nameplate and add a B. Every BRAH 3TF contactor in the catalogue follows that rule.
• The catalogue holds 152 BRAH 3TF contactors across 24 sizes. All are 3-pole and rated 600V, and all are supplied with an AC control coil.
• Coil voltages listed are 24VAC, 110/120VAC, 240VAC and 480VAC on every size, with 208VAC and 277VAC on some.
• The coil voltage must match your control circuit. It is the detail that most often gets ordered wrong.
• If only one part has failed, BRAH also lists 3TY7 coils, 3UA overload relays, contact kits and arc chutes for these contactors. Browse all replacement contactors.

3TF sizes BRAH replaces, with catalogue ratings

The table shows one row for each 3TF size. The linked BRAH part is the base listing for that size. Other listings for the same size differ only in coil voltage or auxiliary contacts. Every listing is 3-pole (3P) and rated 600V. The last column shows the 3UA overload relay series that the catalogue lists for that contactor size.

Treat the amperage and horsepower columns as catalogue values, not as a motor rating for your application. Do not read a rating out of the part number either: the two digits after 3TF are a size code, not an amperage. Match the replacement to the nameplate of the contactor you are removing and to the motor nameplate. Horsepower depends on the supply voltage, so check it against the motor nameplate as well.

How the coil voltage is listed for each part number

On these parts the suffix after the dash goes with the coil. Across the BRAH 3TF listings, the catalogue shows these coil voltages for each suffix:

Use the table to find the right listing, then confirm the coil voltage shown on the product page against the marking on the installed coil and the voltage of your control circuit. A coil fed with the wrong voltage will either fail to pull the contactor in or overheat. All of these are AC coils. If your contactor has a DC coil, call before ordering.

Coils, arc chutes and overload relays for the same contactors

A 3TF contactor with a burnt coil or a damaged arc chute does not always need to be replaced whole. BRAH lists the matching parts separately. The table groups the 3TF sizes by the 3TY7 coil the catalogue lists for them. The coil shown is one example from each group, and the other voltages are under magnetic coils.

Overload relays are listed by series and by current range, so pick a 3UA series listed for your contactor size in the first table and then the range that covers the motor full-load current. See overload relays and the guide to replacing Siemens 3UA overload relays. Arc chutes are listed for 3TF46 through 3TF57 only. What an arc chute does is covered in a separate guide. BRAH also lists 3TY7 contact kits for 3TF44 through 3TF57.

Before you order: what to check on a 3TF

• The full order number. Copy it from the nameplate, including everything after the dash. 3TF4622-0AK6 and 3TF4622-0AV0 are the same contactor with different coils.
• Coil voltage and frequency. Read them from the coil itself and from the control circuit drawing. Do not assume the coil matches the line voltage.
• Auxiliary contacts. Count the normally open and normally closed auxiliary contacts in use. The catalogue lists the arrangement for each part, for example 1 NO on the 3TF30 and 2 NO / 2 NC on the 3TF46.
• Load. Compare the motor nameplate current and horsepower with the catalogue values for the replacement.
• Overload relay. If the old 3UA relay stays, confirm it is listed for the same contactor size. If it is being replaced, match its current range.
• Fit. Compare the mounting holes and terminal positions of the installed contactor with the product page. If you are unsure, ask before ordering.

BRAH Electric designs its parts in-house and tests them at its Carlsbad, California facility. It is an aftermarket manufacturer and is not an authorized Siemens distributor. Contactors carry a 2-year warranty from the date of invoice, and in-stock orders placed before 3:00 PM Pacific ship the same business day. For help with a cross-reference, call (855) 355-2724, Monday to Friday, 6AM to 5PM Pacific.

Safety when changing a contactor

A contactor has line voltage on its power terminals and often a separate control supply on the coil. Before removing one, de-energize the starter or panel, apply lockout/tagout to both the power and the control source, and verify the absence of voltage. The work should be done by qualified personnel. Label the wires before disconnecting them and reconnect the replacement the same way.

Siemens 3TF replacement FAQs

Are Siemens 3TF contactors still made?

No. Siemens has discontinued the 3TF series, and the BRAH catalogue marks the original part numbers as obsolete. Replacements are available as aftermarket parts.

What is the BRAH part number for my 3TF contactor?

Put a B in front of the Siemens number. 3TF4822-0AK6 becomes B3TF4822-0AK6.

Does “3TF46” mean the contactor is rated 46A?

No. The digits are a size code. The BRAH replacement for the 3TF46 has a catalogue rating of 45A, and the 3TF48 is listed at 75A. Always take the rating from the nameplate or the catalogue record.

Can I fit a replacement with a different coil voltage?

Only if you also change the control circuit to suit, which is rarely worth it. Order the listing whose coil voltage matches the existing control supply, or keep the contactor and replace the 3TY7 coil alone.

Will my existing 3UA overload relay work with the replacement?

The replacements are listed as direct substitutes for the Siemens part, and the 3UA relays in the catalogue are listed by 3TF size. Confirm that your relay series is listed for your contactor size in the size table above.

Do I have to replace the whole contactor if the coil has failed?

No. BRAH lists 3TY7 replacement coils for every 3TF size in this guide. Match the coil group to the contactor size and the voltage to the control circuit.

References

• IEC 60947-4-1, Low-voltage switchgear and controlgear: electromechanical contactors and motor-starters. The standard that defines contactor ratings and utilization categories.
• OSHA 29 CFR 1910.147, The control of hazardous energy (lockout/tagout).
• NFPA 70E, Standard for Electrical Safety in the Workplace.