ABB Emax vs Emax 2: Key Differences in Air Circuit Breakers

What is the difference between ABB Emax and Emax 2? The ABB Emax 2 is the second-generation open air circuit breaker series rated 400–6300 A under IEC 60947-2, replacing the original Emax with redesigned frame sizes, higher breaking capacities up to 200 kA, and the Ekip digital trip unit platform in place of the PR231/232/233 architecture. Substituting an Emax 2 unit into an existing Emax installation without verifying mechanical compatibility, accessory pinouts, or trip unit parameterization can cause protection miscoordination or failed type-test compliance. This guide covers why ABB retired the original Emax, frame size and rated current changes, B/N/S/H/L/V breaking capacity levels, PR-versus-Ekip trip unit architecture, retrofit and accessory compatibility, and a direct comparison table.

Published: 2026-04-27 | Last updated: 2026-04-27 | By Stoklink Engineering Team

Why ABB Replaced the Original Emax

The original ABB Emax range (E1 to E6) launched in the early 2000s and served the global low-voltage market for nearly two decades. It was a solid, mechanical-first platform: PR121, PR122, and PR123 trip units, robust drawout chassis, and a broad accessory set. By 2014, three things had changed. Power density expectations in switchgear increased. Customers wanted energy data without bolting on external meters. And IEC 60947-2 had evolved with stricter requirements for category B (selectivity) breakers and more rigorous Icw testing.

In our experience commissioning panels across data centers, marine vessels, and pharmaceutical plants between 2015 and 2020, the pressure point was always the same: clients asked for built-in power quality monitoring and Modbus TCP, and the original Emax with PR122 simply needed too many add-ons to deliver it cleanly. Emax 2 collapsed that complexity into the trip unit itself.

For complete technical specifications and configuration data on the ABB Emax 2 air circuit breaker family, refer to ABB's official SACE Emax 2 product documentation.

Frame Sizes and Rated Currents: What Actually Changed

This is where most procurement engineers get caught out when cross-referencing ABB Emax frames against their Emax 2 successors. The naming looks similar (E1 became E1.2, E2 became E2.2, and so on), but the frame envelopes and current ratings inside each frame are not identical.

Original Emax frames

The legacy Emax stepped through E1 (up to 1250 A at Ue 690 V), E2 (up to 2000 A), E3 (up to 3200 A), E4 (up to 4000 A), and E6 (up to 6300 A). E1 and E2 shared a similar height and width, while E3 was distinctly larger.

Emax 2 frames

Emax 2 reorganizes this. The E1.2 frame now reaches 1600 A in a footprint similar to the old E1 — meaning a former E2 application at 1600 A can often be served by an E1.2, freeing panel space. E2.2 covers 800 A to 2500 A, E4.2 reaches 4000 A, and E6.2 still anchors the top end at 6300 A. The E3 designation effectively disappears.

In practice, this means a direct one-to-one swap from old Emax to Emax 2 is rare. A typical project we handled in 2022 — a paper mill MCC retrofit in Finland — used the ABB 1SDA070701R1 E1.2B 630 A to replace what was originally an E1B 800 A, because actual measured load was 480 A and the new 630 A frame gave us tighter selectivity coordination downstream. The lesson: don't replace by nameplate; replace by load study. For frame-by-frame data, see our Emax 2 full technical specifications guide.

Breaking Capacity: B, N, S, H, L, V Performance Levels

Both ABB Emax generations use letter suffixes to denote breaking capacity, but the available combinations differ.

Icu and Ics ratings

The original Emax E2N 2000 A delivered Icu = 65 kA at 415 V. The Emax 2 E2.2N 2000 A delivers Icu = 66 kA at 415 V — a marginal numerical change but achieved with different arc-chamber geometry and a redesigned contact system. More significantly, Emax 2 standardizes Icw (short-time withstand) at higher values across more frames, which matters enormously for selective tripping in category B applications per IEC 60947-2 Clause 4.3.5.4.

For applications where you need 42 kA at 415 V across a 1000 A feeder, the ABB 1SDA070781R1 E1.2B 1000 A hits that target in a noticeably more compact enclosure than the equivalent legacy E1B would have.

Trip Unit Architecture: PR vs Ekip

This is the single largest functional gap between the two ABB Emax generations.

Legacy PR121/122/123 family

The original Emax used the PR121 (basic LSI/LSIG protection), PR122 (with measuring), and PR123 (with full power quality and dialogue). These were capable units in their day, but firmware updates required a service laptop, and protocol options were limited to Modbus RTU over RS-485 with optional Profibus DP gateways.

Ekip family on Emax 2

Emax 2 introduces Ekip Dip, Ekip Touch, Ekip Hi-Touch, and the G versions with embedded earth-fault and power management. Ekip Touch is a color touchscreen on the breaker face — operators see harmonic spectra, voltage unbalance, and trip event logs without an HMI. Ekip Link, Ekip Modbus TCP, Ekip Profinet, and Ekip Ethernet/IP modules plug directly into the trip unit's connectivity slot. No external gateway.

Engineers often overlook one practical consequence: Emax 2 trip units enforce stricter cyber-security defaults out of the box (per IEC 62443 alignment), so on a commissioning we had to coordinate with the client's IT team to whitelist breaker IP addresses before the SCADA could poll them. That was never an issue with PR123. It is now.

Mechanical Compatibility, Accessories, and Retrofit

A common mistake is assuming that Emax 2 drops into an existing ABB Emax cradle. It does not. The drawout chassis, racking-in mechanism, terminal positions, and door-frame cutout are different.

What is interchangeable

Almost nothing mechanically. The only items that survive are some control voltage conventions (24 Vdc, 110/220 Vac coil ratings) and the general philosophy of LSIG protection settings.

What is not

Cradles, terminals (horizontal vs vertical), shutters, racking handles, door escutcheons, motor operators, undervoltage releases, shunt trips, and auxiliary contact blocks are all different part numbers. ABB publishes a dedicated retrofit kit catalogue precisely because the swap is non-trivial.

Retrofit strategy in practice

For a 2023 cement plant project in Morocco, we faced 14 legacy E2N 1600 A breakers due for replacement. Two options were on the table: full panel rebuild, or use ABB's retrofit conversion plates that adapt the new breaker to the existing cubicle. We went with the conversion route on 11 panels and full rebuild on 3 (where bus bracing was also at end-of-life). Total saving: roughly 38% versus a complete switchgear replacement.

Comparison Table: Emax vs Emax 2 at a Glance

Communication, Power Management, and Digital Features

The original ABB Emax with PR123 could push current, voltage, and energy registers over Modbus RTU. Useful, but limited. Emax 2 reframes the breaker as a node on the plant network.

Native protocol stack

Emax 2 supports Modbus RTU, Modbus TCP, Profibus DP, Profinet, EtherNet/IP, and IEC 61850 (with Ekip Com IEC 61850 module). For utility substations and large industrials moving toward IEC 61850-9-2 sampled values, this is decisive.

Ekip Power Controller

One feature with no equivalent on the legacy Emax: the Ekip Power Controller function. It allows the breaker to actively shed loads or block load-on commands when measured power approaches a configurable contracted limit. We deployed this on a hospital project to enforce a 2.4 MW utility contract cap — the breaker itself, not an external PLC, managed the cap. That capability simply did not exist on PR123.

For data center applications where every millisecond of trip discrimination matters, the Emax 2 in data center MDB design article walks through the redundancy patterns we now consider standard.

Sizing Calculator: Choosing an Emax 2 Frame

For a deeper sizing methodology including selectivity tables, see our step-by-step Emax 2 sizing calculator.

When to Choose Emax 2 — and When the Original Still Makes Sense

Some engineers argue you should always specify the latest ABB Emax generation. In my experience, that's an oversimplification. There is no universal answer because it depends on the installed base, spares strategy, and project lifecycle.

Specify Emax 2 when:

You are building a new switchboard from scratch. You need IEC 61850 or Profinet natively. Energy metering accuracy must be Class 0.5. The plant has an active digitalization roadmap. You are integrating with ABB Ability or a modern SCADA. Cyber-security compliance is in the spec.

Stay with original Emax (or buy NOS spares) when:

You are maintaining a 2008-vintage switchboard with 11 identical breakers and need one spare to match exactly. Mixing generations on the same bus risks selectivity miscoordination. The plant has no digital roadmap and the existing PR123 telemetry is sufficient. Budget for a full retrofit is not yet approved.

For a sister-product comparison, our Emax 2 vs Schneider MasterPact MTZ comparison covers the cross-vendor decision in detail. And if you are dealing with unexplained trips on either generation, the Emax 2 nuisance tripping diagnostic guide covers the root causes we see most often in the field.

Procurement Reality: Spares, Lead Times, and Lifecycle Status

ABB has formally moved the original ABB Emax into the "classic" lifecycle phase. New units are no longer manufactured for most frames; what circulates in the market is service stock, refurbished units, and what distributors hold. Lead times for legacy E3N or E4S spares can stretch to 16–24 weeks and prices have risen sharply.

Emax 2 is in active production. Standard fixed-mount frames like the ABB 1SDA070741R1 E1.2B 800 A and ABB 1SDA070821R1 E1.2B 1250 A are typically available with 4–8 week lead times in Europe. The full air circuit breaker range at Stoklink covers both fixed and drawout variants. Complementary protective devices in miniature circuit breakers, residual current devices, and control relays round out a typical LV panel build.

Related Reading

• What Is the ABB SACE Emax 2? Features, Models and Key Benefits
• ABB Emax 2 Full Technical Specifications: Current Ratings, Breaking Capacity and Dimensions
• How to Size ABB Emax 2: Step-by-Step Calculator for LV Distribution Panels
• ABB Emax 2 Nuisance Tripping: Root Causes, Diagnostic Steps and Fixes

Conclusion: A Generational Shift, Not a Facelift

The move from Emax to Emax 2 is not a cosmetic refresh. It is a generational shift in what an air circuit breaker is expected to do. The original Emax was a protection device with optional metering. Emax 2 is a protection device, a power meter, a network node, and a load controller in one frame — and it does this while offering higher current density and tighter selectivity than its predecessor.

For new projects, specify Emax 2 by default. For existing installations, plan retrofits around ABB's conversion kits rather than full panel rebuilds where the cubicle structure is sound. And always — always — re-evaluate frame size, breaking capacity, and selectivity coordination against the current load study, not the nameplate of the breaker you are removing. For the complete selection methodology, application examples, and maintenance procedures, see our ABB SACE Emax 2 selection, application and maintenance guide, and for the broader product context the air circuit breaker engineering guide covers the full LV ACB landscape.

The legacy Emax served the industry well for nearly twenty years. Emax 2 is built for the next twenty.