ABB / AF contactors and overload relays

The full AF range with AC-3 ratings at 400 V and 415 V, the wide-range coil that replaces four part numbers, and the R versus M letter that decides whether a power bus is included.

AF is the current ABB contactor range and it has largely replaced the older A series. Block type, three main poles, and an electronic coil interface that is the range's defining feature.

Reading an AF number

Take AF09-30-10-13, order number 1SBL137001R1310.

So an AF09-30-22-13 has 2 normally open and 2 normally closed auxiliaries.

AC-3 ratings, and why 415 V matters here

New Zealand supply is nominally 400 V but plenty of plant runs at 415 V, and ABB rates several AF contactors higher at 415 V than at 400 V.

Ratings are AC-3 at ambient up to 60 degrees C for AF09 to AF370.

AF38 and AF40 are not the same thing

Both give 18.5 kW at 400 V, which makes them look interchangeable. At 415 V the AF38 is still 18.5 kW and the AF40 is 22 kW.

They are also in different accessory groups. AF09 to AF38 is one family for auxiliary blocks and AF40 to AF96 is another. So substituting one for the other may fit the motor and not fit the accessories.

The wide-range coil

The reason to standardise on AF, and a genuine saving on a spares store.

ABB states the AF range uses an electronic coil interface accepting a wide control voltage range, with only 4 control voltage ranges covering 24 to 500 V at 50/60 Hz and 20 to 500 V DC.

Coil code 13 covers 100 to 250 V AC and 100 to 250 V DC. One part number covers 110 V, 120 V, 200 V, 208 V, 220 V, 230 V and 240 V AC, plus 110 V and 220 V DC.

Four coil codes cover essentially every control voltage in a plant. Compare that with holding a separate contactor for each voltage.

The AF..Z variants cover 24 to 250 V at 50/60 Hz and 12 to 250 V DC.

The polarity exception

One case where polarity matters, from the ABB catalogue.

AF..Z contactors with a 12 to 20 V DC control voltage must respect the connection polarity marked at the coil terminals: A1 positive, A2 negative.

Every other AF coil is polarity-independent. If you have low-voltage DC control on Z contactors, that is the exception to know.

R and M: the reversing contactor letter

A useful detail that is easy to miss.

ABB supplies pre-assembled reversing contactors as AF09R to AF30R and AF40R to AF96R. These include two 3-pole contactors, a mechanical and electrical interlock, and a power bus, assembled with fixing clips.

ABB states plainly: for mechanically and electrically interlocked devices without the power bus, replace the R in the catalogue number with an M.

One letter, and one version arrives without the busbars linking the two contactors. If you order an M expecting a complete reversing starter you will be making up links.

Note also from our ABB overview that interlocking reversing pairs need no spacing between contactors, so a reversing starter takes less rail than you might allow.

Auxiliary contacts

The blocks

Mechanically linked contacts

Important for safety circuits. ABB specifies that built-in auxiliary contacts and additional CA4, CAL4 and CAT4 auxiliary contacts are mechanically linked contacts.

Mechanically linked means a normally closed auxiliary cannot close while a main contact is welded, which is what allows a safety circuit to detect a failed contactor. Same principle as the Omron G7SA range on our Omron relay page.

Do not substitute an auxiliary block that is not mechanically linked into a safety circuit. The usual caution applies: that decision belongs to whoever is responsible for the machine's safety assessment.

Fitting limits

From the ABB catalogue:

• 4 normally closed maximum on positions 1, 2, 3 and 4
• 3 normally closed maximum on positions 1 at 30 degrees, and 5
• With one CE5 fitted, 2 add-on normally closed maximum
• With two CE5 fitted, no add-on normally closed contacts
• No add-on normally closed contacts on positions 1 at 30 degrees, or 5

Fitting an overload relay does not prevent fitting other accessories.

Auxiliary contact ratings

Worth checking before you switch anything substantial through an auxiliary.

AC-15

DC-13, and how fast it drops

The same auxiliary contact is a 6 A device at 24 V DC and a 0.15 A device at 400 V DC. DC arcs do not self-extinguish the way AC does, which is why the rating collapses as voltage rises.

If an auxiliary contact keeps failing on a DC circuit, this table is where to look before assuming a faulty contactor.

Conventional free air thermal current Ith is 16 A at ambient up to 40 degrees C.

Coil power consumption

Useful when sizing a control transformer or a 24 V supply feeding a bank of contactors.

These are low figures, which is the other advantage of the electronic coil. A bank of twenty AF09 contactors draws under 50 W held in at AC-3.

The full AF range

AF1250 to AF2650 have low voltage inputs for control, so they can be driven directly from a PLC output rather than through an interposing relay.

Ambient rating is up to 60 degrees C for AF09 to AF370 and up to 55 degrees C for AF400 to AF2650.

Overload relays and motor protection

ABB notes that MS165 and MO165 are suitable for use with AF09 to AF30 for North American applications, and that the BEA65-4 suits MS165 and MO165 only.

Overload relays are matched to the contactor frame. Tell us the contactor and the motor full load current and we will quote the matching relay with the right setting range.

Replacing an older A series contactor

The A series preceded AF and there is a lot of it installed.

AF is generally the successor, but the coil behaviour is different. An A series contactor has a conventional coil wound for one voltage. An AF has an electronic interface with a wide range.

That is usually an improvement, but check two things: the physical footprint, and whether anything in the control circuit relied on the old coil's characteristics.

What we can supply

Current production. The full AF range from AF09 to AF2650, reversing assemblies, auxiliary blocks, overload relays, manual motor starters and accessories. Quoted with a delivered lead time.

Discontinued. A series contactors and older overload relays. Surplus and tested used.

Bulk. Contactors and auxiliary blocks are consumables in any motor control centre. Send us the list.

Related

ABB overview. ACS550 and ACS580 and ACS880.

For contactors from other brands see Siemens SIRIUS and Allen-Bradley 100-C. For hybrid alternatives see Phoenix Contact CONTACTRON.

Send us your part numbers

Send the full designation including the coil code. If you need a reversing pair, tell us whether you want the power bus, because that is the R versus M letter. Quotes in NZD including GST.

Request a quote

Industech is an independent supplier of new, surplus and used industrial automation equipment. We are not an authorised distributor of, approved by, sanctioned by, or affiliated with ABB Ltd. ABB is a trademark of ABB Ltd. All trademarks, brand names and part numbers are the property of their respective owners and are used here for identification purposes only. Information on this page is for identification and does not constitute a safety assessment.