How to Cross Reference Siemens Contactors to Modern Equivalents

To cross a Siemens contactor to a BRAH Electric replacement, read the full order number from the nameplate and put a B in front of it: a 3TF4622-0AK6 becomes a B3TF4622-0AK6 and a 3RT1026-1AK61 becomes a B3RT1026-1AK61. That rule holds for every Siemens contactor in the BRAH catalogue, which covers the 3TF, 3TB and 3TH World Series and the 3RT Sirius series. The replacement is listed as a direct substitute for the Siemens number, so the cross-reference is a matter of copying the number correctly and then checking the coil voltage and ratings on the listing.

This guide shows which Siemens series and sizes are covered, how the suffix sets the coil voltage, and how to look a number up with the product search. The 3TF sizes have their own table in the Siemens 3TF replacement guide, so they are summarized here and not repeated.

Siemens to BRAH cross-reference in four steps

• 1. Copy the whole number. Take it from the nameplate on the contactor, not from a drawing that may be out of date. Include every character after the dash.
• 2. Add the B and search. Type the Siemens number, or the same number with a B in front, into the search box on the products page. Typing the number without its suffix shows every coil version of that size.
• 3. Compare the listing with the old unit. Check poles, coil voltage, the catalogue amperage and horsepower, and the auxiliary contacts against the nameplate and the motor.
• 4. Check the parts around it. Coils, overload relays, contact kits and auxiliary blocks cross the same way. For anything not in the tables below, call (855) 355-2724 with the part number.

Siemens contactor series in the BRAH catalogue

The table gives one row per series. Amperage is the range of catalogue ratings across the sizes shown, and every listing is rated 600V. The last column is a worked example of the B-prefix rule.

The 3TF series is by far the largest group. Its 24 sizes, their ratings and the full suffix table are in the 3TF guide, and the 3TF44 has a page of its own. The rest of this guide gives the detail for the 3RT, 3TB and 3TH numbers.

3RT Sirius contactors: sizes, ratings and coil suffixes

A 3RT order number has two parts. The seven characters before the dash, such as 3RT1026, give the size. The suffix after the dash gives the coil. A listing with no suffix is supplied with a 120VAC coil. Every row below is 3-pole and 600V.

Two things in this table catch people out. First, the 24VAC suffix is -1AB01 on the sizes up to 3RT1026 and -1AC21 from 3RT1034 upward, so copy the suffix from your own contactor and do not carry it over from a different size. Second, sizes cannot be told apart by amperage alone: 3RT1016 and 3RT1023 are both listed at 9A, and 3RT1017 and 3RT1024 at 12A. They are different contactors with different part numbers. The 3RT1015, 3RT1016 and 3RT1017 listings include one normally open auxiliary contact.

Read the amperage and horsepower columns as catalogue values to compare with the nameplate. They are not a calculation of what your motor needs.

3TB and 3TH World Series numbers

The 3TB contactors are listed in five sizes, each as a short number and as a four-digit number. Both forms are supplied with a 110/120VAC coil and 2 NO / 2 NC auxiliary contacts.

The 3TH numbers are listed as 4-pole parts with a 120VAC coil. The last two digits of the four-digit number follow the auxiliary contact arrangement, so 3TH4022 and 3TH4044 are separate listings.

How the suffix sets the coil voltage

On Siemens contactors the coil is identified by the suffix, and the same suffix letters mean the same thing on the replacement. In the BRAH listings for 3TF contactors, -0AC2 is 24VAC, -0AK6 is 110/120VAC, -0AP6 is 240VAC and -0AV0 is 480VAC. For 3RT contactors the suffixes are the ones in the table above. A listing without a suffix is supplied with a 110/120VAC or 120VAC coil, so a bare size number is enough to order from only when that is the coil you need.

The coil voltage must equal the control circuit voltage, which is frequently different from the motor supply. If the nameplate is unreadable, the coil usually carries its own label with voltage and frequency. Give that to BRAH along with the size and the right listing can be identified.

Coils, overload relays and other parts cross the same way

The B-prefix rule is not limited to complete contactors. The Siemens spare-part numbers in the catalogue follow it as well, which helps when only one component has failed.

Overload relays are chosen by series and by current range. The guide to replacing Siemens 3UA overload relays explains how. What an arc chute does, and when one needs replacing, is covered in the arc chute guide.

Direct substitute or a different series

“Modern equivalent” can mean two different things, and the cost of each is very different. A direct substitute is a currently manufactured part made to take the place of the original under the same number. The wiring, the overload relay and the panel layout stay as they are. That is what the BRAH parts in this guide are listed as.

Moving to a contactor from a different series or a different manufacturer is a redesign. Mounting, terminal positions, coil data, auxiliary contact arrangement and the overload relay may all change, and the selection should be made by a qualified engineer against the motor data and the applicable standards. Matching amperage alone is not a cross-reference.

Before you order: what to check

• Series and size. 3TF, 3TB, 3TH or 3RT, followed by the size digits. A 3TF44 and a 3TB44 are separate listings.
• Suffix. The characters after the dash, copied exactly.
• Coil voltage and frequency. From the coil label and the control circuit.
• Poles. 3-pole for 3TF, 3TB and 3RT listings and 4-pole for 3TH.
• Auxiliary contacts. The number of normally open and normally closed contacts the control circuit uses.
• Motor nameplate. Full-load current and horsepower at your supply voltage, compared with the catalogue values.
• Overload relay. Its series and current range if it is staying in place.

BRAH Electric designs its parts in-house and tests them at its facility in Carlsbad, California. It is an aftermarket manufacturer and is not an authorized Siemens distributor. The warranty is 2 years from the date of invoice, or 6 months for contact kits. In-stock orders placed before 3:00 PM Pacific ship the same business day. The phone line is open Monday to Friday, 6AM to 5PM Pacific.

Safety note

A cross-reference is paperwork, but reading a nameplate inside a live starter is not. Take the number with the door closed if it is visible through a window or recorded on the panel schedule. If the enclosure has to be opened, or the contactor removed, the circuit must be de-energized, locked out and tagged, and proved dead by qualified personnel first.

Siemens contactor cross-reference FAQs

What is a Siemens contactor cross-reference?

It is the step of matching a Siemens order number to a replacement part that can take its place. With BRAH parts the match is by number: the replacement carries the Siemens number with a B prefix.

How do I find the BRAH part for my Siemens contactor?

Enter the Siemens number in the product search, or add a B to the front of it. Then confirm the coil voltage on the listing matches your control circuit.

Does the suffix after the dash matter?

Yes. It identifies the coil. 3RT1026-1AK61 is listed with a 120VAC coil and 3RT1026-1AV61 with a 480VAC coil. They are otherwise the same size of contactor.

Which Siemens series does BRAH list replacements for?

Contactors in the 3TF, 3TB and 3TH World Series and the 3RT Sirius series, together with 3TY7 and 3RT19 coils, 3UA overload relays, contact kits, auxiliary contacts and arc chutes. For anything not in the tables, call (855) 355-2724 with the part number.

Can I pick a replacement by amperage if I cannot read the number?

No. Several sizes share a catalogue amperage, for example 3RT1016 and 3RT1023 at 9A. Identify the contactor from the coil label, the panel drawings or the equipment records, or call with what you can read.

Can I use another brand as an equivalent?

Only as an engineered change. A different contactor may differ in mounting, terminals, coil and overload relay, so it needs to be selected by a qualified person. A direct substitute under the same number avoids that work.

References

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