ABB Emax 2 Retrofit Guide: Replacing Obsolete Emax E1 E2 E3 E4 E6 ACBs
What is an ABB Emax 2 retrofit? An ABB Emax 2 retrofit is the structured replacement of first-generation Emax E1–E6 air circuit breakers — rated 800–6300 A under IEC 60947-2 with breaking capacities up to 150 kA — with current-production Emax 2 frames using compatible fixed or withdrawable mounting footprints. Overlooking dimensional tolerances, trip unit parameter mapping, or frame-to-frame rating differences risks miscoordination, protection gaps, or non-compliant installations that fail arc-flash and selectivity studies. This guide covers end-of-life drivers for the original Emax series, mechanical and dimensional compatibility across E1–E6 frames, PR111/121/122-to-Ekip trip unit migration, replacement sizing methodology, a frame-by-frame substitution map, and real-world retrofit scenarios.
Why the Original Emax (E1–E6) Reached End-of-Life
The original Emax family launched in the late 1990s and dominated the global low-voltage market for nearly two decades, until the ABB Emax 2 platform took over as the successor line. ABB formally announced the phase-out around 2014, with the last production runs of certain frame sizes wrapping up by 2018. Spare parts — closing coils, motor operators, PR121/PR122 trip units — are now sourced primarily from refurbished stock or end-of-batch warehouses.
In our experience, the trigger for retrofit is rarely a catastrophic failure. It's usually one of three things: a failed trip unit that can't be replaced in under 12 weeks, a short-circuit study that flags inadequate Icw at the new fault level, or an arc-flash assessment that demands faster clearing times than the old electromechanical PR111 can deliver. A common mistake is waiting until the breaker fails. By then, the panel is offline, production is bleeding revenue, and the procurement team is paying premium air-freight to ship a unit that may still need on-site commissioning.
Dimensional and Mechanical Compatibility: E1–E6 to Emax 2
ABB designed the ABB Emax 2 with explicit retrofit intent. The frame sizes map roughly as follows: E1 → E1.2, E2 → E2.2, E3 → E4.2, E4 → E4.2, E6 → E6.2. The "0.2" generation shares the same depth and most mounting hole patterns, but width and terminal positioning have changed in several cases — particularly when migrating from E3 (which had a wider frame) to the more compact E4.2.
Fixed vs Withdrawable: Watch the Cradle
Withdrawable retrofits are where projects stall. The original Emax cradle is not directly compatible with Emax 2. ABB offers dedicated retrofit kits (the "Retrofill" range in some regions) that include a transition cradle, secondary disconnect adapter, and shutter mechanism. Fixed-version replacements are simpler — typically a busbar drilling check and a cable lug verification. For new fixed installations or full panel rebuilds, the ABB 1SDA070701R1 E1.2B 630 A and ABB 1SDA070741R1 E1.2B 800 A are the natural replacements for legacy E1B 630/800 units.
Trip Unit Migration: From PR111/121/122 to Ekip
The Ekip trip unit family is where the real engineering value of the ABB Emax 2 lives. The legacy PR111 (electromechanical) and PR121/122 (early electronic) units are functionally replaced by Ekip Dip, Ekip Touch, and Ekip Hi-Touch. Migration is not just a swap — protection settings, communication protocols, and selectivity coordination all need review.
Mapping Legacy Settings to Ekip
Engineers often overlook that the original PR121 used current taps in fixed steps (0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, 1.0 × In), while Ekip Dip and Ekip Touch allow continuous adjustment in 0.01 × In increments. This is a real benefit for selectivity tuning, but it also means your existing coordination study needs re-validation. A common field error: copying the old PR121 settings verbatim into Ekip and assuming the time-current curve is identical. It isn't. The Ekip I² t and I⁴ t curve shapes differ slightly at the inverse-time knee.
For applications that previously used PR122 with PR120/V voltage module, the equivalent today is typically Ekip Touch with Ekip Measuring. The ABB 1SDA070782R1 E1.2B 1000 A Ekip Dip LSI is a typical mid-range retrofit choice when the existing study calls for short-time protection but no metering.
Sizing the Replacement: Don't Just Match the Old Rating
The most expensive mistake in ABB Emax 2 retrofit projects is one-for-one rating replacement without recalculating fault levels. Transformers get upgraded. Generators get added. Utility short-circuit contributions creep up over 20 years. What was 36 kA in 2002 may be 50 kA today.
Formula: Required Breaking Capacity — Source: IEC 60947-2 §4.3.5
Icu ≥ Ik" × ksafety
| Symbol | Description | Unit |
|---|---|---|
| Icu | Rated ultimate breaking capacity of the breaker | kA |
| Ik" | Initial symmetrical short-circuit current at point of installation | kA |
| ksafety | Margin factor (typically 1.10–1.25 for future load growth) | — |
For a deeper sizing walkthrough, see our guide on how to size ABB Emax 2 for LV distribution panels. For a quick first-pass estimate, use the calculator below.
Frame-by-Frame Replacement Map
Below is a working reference we use for screening ABB Emax 2 retrofit quotes. It's not a substitute for ABB's official cross-reference, but it covers 80% of the cases we see in industrial MDBs across cement plants, water treatment facilities, and data centers.
| Legacy Emax | Typical Rating | Emax 2 Replacement | Notes |
|---|---|---|---|
| E1B 800 | 800 A / 42 kA | E1.2B 800 (1SDA070741R1) | Direct fixed retrofit; verify lug centers |
| E2N 1600 | 1600 A / 65 kA | E1.2B 1600 (1SDA070861R1) or E2.2N | Choose E2.2N if fault >42 kA |
| E3N 2500 | 2500 A / 65 kA | E2.2N 2500 or E4.2N 2500 | E2.2 is more compact; check cubicle width |
| E4S 4000 | 4000 A / 75 kA | E4.2S 4000 | Withdrawable kit required |
| E6H 6300 | 6300 A / 100 kA | E6.2H 6300 | Verify busbar phase spacing |
For 1000 A and 1250 A applications — common in mid-size pumping stations and MV/LV transformer secondaries — the ABB 1SDA070781R1 E1.2B 1000 A and ABB 1SDA070821R1 E1.2B 1250 A cover the bulk of replacements. When fault levels exceed 42 kA, step up to E2.2 with the 1SDA070981R1 E2.2B 1600 A.
Real-World Retrofit Scenarios
Scenario 1: Cement Plant MV/LV Substation, Turkey
A 2001-vintage substation with four E3N 2500 incomers feeding kiln auxiliaries. The PR122 trip units had drifted out of calibration on two of the four breakers, and ABB confirmed parts lead time of 26 weeks. The plant chose to retrofit all four during a planned 7-day kiln shutdown using ABB Emax 2 E4.2N 2500 withdrawable units with Ekip Touch LSIG. Total project: $182k including engineering, selectivity restudy, and arc-flash labels per IEEE 1584-2018. Payback was justified entirely by avoided unplanned downtime risk — at €12k per hour of kiln stoppage, the math is straightforward.
Scenario 2: Data Center Tier III, Frankfurt
Six E2N 1600 main breakers in a 2008-build MDB, supporting a 2N redundant UPS topology. The retrofit driver was protocol — the legacy PR122/P with Modbus RTU couldn't integrate with the new BMS over IEC 61850. Migration to Emax 2 E2.2N with Ekip Hi-Touch and Ekip Com IEC 61850 modules was completed without any IT load loss, using the redundant feed to isolate one breaker at a time. For more on this topology, see our piece on Emax 2 in data center MDB design.
Scenario 3: Pulp Mill Genset Switchgear, Brazil
Two E4H 4000 generator breakers from 2005, suffering chronic nuisance trips during paper machine startup transients. Root cause analysis pointed to the PR121 instantaneous element responding to inrush. The retrofit to E4.2H with Ekip Dip LSI and proper short-time delay tuning eliminated the issue. We've covered this failure mode in detail in our analysis of Emax 2 nuisance tripping causes.
Procurement and Lead-Time Strategy
Procurement managers ask one question repeatedly: do we buy the new ABB Emax 2, or hunt down a refurbished E2 on the gray market? In most cases, the new unit wins — but the analysis depends on remaining plant life, criticality, and whether the original spare parts ecosystem still exists.
What we typically see in the field: refurbished Emax E1–E6 units carry no warranty beyond 90 days, no calibration certificate for the trip unit, and no path to firmware updates. For a non-critical tie breaker in a secondary panel, that's acceptable. For a main incomer feeding production load, it's a false economy. The ABB 1SDA071021R1 E2.2B 2000 A with full factory warranty and IEC 60947-2 type-test compliance typically costs only 15–20% more than a refurbished E2N 2000 — and that delta is recovered the first time you need a spare part.
Stoklink stocks the full air circuit breaker range for fast EU and global dispatch, alongside complementary MCBs, RCDs, and protection relays for full-panel refurbishment projects.
Commissioning and Testing After Retrofit
ABB Emax 2 retrofit projects fail at commissioning more often than at installation. The breaker is mechanically fine, the wiring is correct, but the trip unit settings haven't been validated against the upstream and downstream coordination. Per IEC 60947-2 §8.3.6, secondary injection testing is required after any trip unit change. Primary injection is recommended where practical — particularly for the instantaneous element, which can shift behavior between PR121 and Ekip due to differences in current sensor design.
A practical commissioning checklist we use: verify Ekip firmware matches the latest stable release, confirm CT ratio matches the rating plug, perform secondary injection at 1× In, 2× In, and 6× In, validate trip times against IEC 60255-151 inverse-time curve tolerances (±15%), and capture the test report as part of the maintenance record. Skip any of these and you're flying blind.
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
- ABB Emax 2 vs Schneider MasterPact MTZ: Technical Specs, Features and Price Compared
- ABB Emax 2 Nuisance Tripping: Root Causes, Diagnostic Steps and Fixes
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Frequently Asked Questions
Is the Emax 2 cradle backward-compatible with the original Emax cradle?
No. The cradles are mechanically and electrically different. ABB provides retrofit transition kits that allow an ABB Emax 2 breaker to be installed in the original Emax cubicle position, but the cradle itself must be replaced. Always order the retrofit kit alongside the breaker — it includes the secondary disconnect adapter and shutter mechanism required for safe withdrawal operations.
Can I reuse my existing PR121/PR122 settings on the new Ekip trip unit?
Use them as a starting point only. Ekip trip units have higher resolution and slightly different curve shapes, so direct copy-paste of pickup and delay values can produce coordination mismatches. We strongly recommend re-running the full selectivity study. See our Emax 2 sizing calculator for an updated workflow.
How long does a typical Emax retrofit take?
For a fixed unit, plan 4–6 hours per breaker including isolation, removal, installation, and commissioning. For withdrawable retrofits with a new cradle, plan 1–2 days per cubicle. Multi-breaker projects benefit from a planned outage window of 3–7 days, depending on plant complexity and whether you can use bypass or temporary feeds.
Do I need to update arc-flash labels after the retrofit?
Yes, in nearly all cases. Faster trip times under Ekip generally reduce incident energy, which means your existing labels are conservative — but per IEEE 1584-2018 and NFPA 70E, the labels must reflect the actual installed equipment. Re-run the arc-flash study and reissue labels as part of project closeout.
What's the typical price premium for new Emax 2 versus refurbished legacy Emax?
In the 800–2000A range, expect a 15–25% premium for new Emax 2 over a reputable refurbished E1/E2 unit. Above 2500 A, the gap narrows because refurbished E3/E4 inventory is scarce and prices have risen sharply since 2020. Factor in warranty, calibration, and the cost of a future spare-parts hunt — the new unit usually wins on total cost of ownership.
Can Emax 2 communicate with my existing SCADA over Modbus RTU?
Yes. Ekip Touch and Ekip Hi-Touch support Modbus RTU, Modbus TCP, Profibus DP, Profinet, EtherNet/IP, and IEC 61850 via plug-in Ekip Com modules. If your existing SCADA was polling a PR122/P over Modbus RTU, register mapping has changed in the Ekip family, so the SCADA configuration needs an update — but the physical RS-485 wiring can typically be reused.
Is partial retrofit (some old, some new) acceptable in the same switchboard?
Technically yes, and we see it often during phased capex programs. The caveat is selectivity: legacy PR121 and modern Ekip have different curve tolerances, so the coordination study must be redone for the mixed configuration. Document clearly which breakers are scheduled for the next phase to avoid confusion during future maintenance.
Conclusion
Retrofitting obsolete Emax E1–E6 ACBs to the Emax 2 platform is one of the highest-leverage lifecycle decisions a facility can make. The mechanical compatibility is good but not perfect — cradles, busbar interfaces, and lug positions all need verification before the PO is issued. The Ekip trip unit ecosystem delivers genuine engineering value: faster clearing times, better selectivity resolution, modern communication protocols, and a parts pipeline that will be supported for the next two decades. None of that matters if the project is rushed, the coordination study is skipped, or the retrofit kit arrives a week late.
In our experience, the projects that succeed share three traits: drawings are overlaid before ordering, retrofit kits are bundled with the breakers in a single PO, and commissioning includes secondary injection testing on every unit. The projects that fail skip one or more of these steps and discover the problem at energization — when the cost of fixing it has multiplied by ten.
For the full selection methodology, coordination study workflow, and maintenance framework, return to our ABB SACE Emax 2 selection, application and maintenance guide. For sourcing, the full Emax 2 range is in stock at Stoklink with global dispatch and full ABB factory warranty — including the most-requested retrofit SKUs from 630 A through 6300 A.
