How to Select the Correct Ekip Trip Unit for ABB Emax 2 Breakers

What is an Ekip trip unit? An Ekip trip unit is the microprocessor-based protective relay module installed within ABB Emax 2 air circuit breakers, governing overcurrent protection across frame sizes from 400 A to 6300 A under IEC 60947-2, with variants spanning basic fixed-function to fully programmable, communication-capable configurations. Specifying the wrong variant — mismatched protection function code, incorrect frame-to-rating alignment, or absent ground-fault (G) or neutral (N) protection — risks failed selective coordination, nuisance tripping, or IEC 61439 switchboard non-compliance. This guide covers protection function codes (LI, LSI, LSIG, LSIGN), frame-size-to-load-current matching, Ekip Touch versus Hi-Touch versus Dip interface selection, selectivity-driven trip unit choices, and communication and cybersecurity module requirements.

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

If you have ever opened a switchboard and found a 1600 A frame fitted with an Ekip Dip LI when the single-line diagram clearly required short-time delay (S) and ground-fault (G), you already know why this topic matters. The trip unit is the brain of the breaker. Frame, breaking capacity, and accessories are mechanical; the Ekip is what determines whether the installation actually coordinates with the rest of the protection scheme.

What Exactly Is an Ekip Trip Unit, and Why Does the Variant Matter?

The Ekip family is ABB's electronic trip unit platform for the ABB Emax 2 and Tmax XT ranges. Unlike the older PR121/PR122/PR123 units used on the original Emax, Ekip is modular: the same physical housing can host different protection function sets, measurement modules, and communication daughter-cards. That modularity is a blessing for the catalog manager and a trap for the specifier who treats "Ekip" as a single product.

In our experience working with EPC contractors across the Gulf and Southeast Asia, roughly 60% of specifications written by junior engineers either over-specify (Ekip Hi-Touch LSIG with measurement on a simple motor feeder) or under-specify (Ekip Dip LI on a main incomer where ground-fault detection is mandated by the local code). Both errors cost money. Over-specification inflates the BOM and delays delivery because higher Ekip variants have longer lead times. Under-specification gets caught at FAT and forces a swap, which on Emax 2 is straightforward mechanically but painful logistically.

The Ekip Hierarchy at a Glance

ABB groups Ekip units into five tiers, each with progressively richer functionality:

• Ekip Dip — DIP-switch configurable, LI or LSI protection, no display, no measurement.
• Ekip Touch — colour LCD, full LSIG protection, basic measurement (I, V, P, E).
• Ekip Hi-Touch — adds advanced protections (directional, voltage-based, frequency), Class 1 metering.
• Ekip G Touch / G Hi-Touch — adds dedicated ground-fault transformer input.
• Ekip M Touch / M Hi-Touch — motor protection variant (thermal image, locked rotor, phase loss).

Each tier is then suffixed with the protection function code: L (long-time, thermal-equivalent overload), S (short-time delay, selective short-circuit), I (instantaneous), G (ground-fault), N (neutral protection), D (directional), U (under/overvoltage), F (frequency).

For complete technical specifications and protection function details of the ABB Emax 2 air circuit breaker family, refer to ABB's official SACE Emax 2 product documentation, which covers the full range of frames, Ekip trip units, and accessories certified to IEC 60947-2.

How Do I Read the Protection Function Code (LI, LSI, LSIG, LSIGN)?

The function code is the part most engineers get wrong on the ABB Emax 2. It looks simple but encodes which curves the trip unit can produce. A common mistake is assuming "more letters equals more protection always wins" — wrong, because each added function requires a tested coordination study. Adding S without verifying selectivity with the upstream transformer secondary protection can create blind spots.

L — Long-Time Protection (Always Required)

L is the thermal overload function. Per IEC 60947-2 §8.3.3.1.1, the L curve must trip at 1.3 × Ir within the conventional time (typically 2 hours for currents below 630 A, 4 hours above). The Ir setting on Emax 2 ranges from 0.4 to 1.0 × In in steps of 0.01, which is finer than the 0.05 steps you find on most MCCBs. That granularity matters when you are coordinating with a downstream MCCB that has its own Ir setting — a 5% mismatch in pickup can collapse the selectivity margin.

S — Short-Time Delay (Selective Short-Circuit)

S is the function that gives Emax 2 its selectivity advantage. By holding the trip for a defined delay (50 ms to 800 ms, with optional I²t curve), the upstream Emax can wait for a downstream device to clear a fault. Without S, you are stuck with instantaneous-only tripping, and the upstream breaker will race the downstream — usually winning, which is exactly what you do not want.

I — Instantaneous

I is the high-current cutoff. Settings on Emax 2 range from 1.5 to 15 × In, plus an OFF position. Many engineers leave I enabled by default; in coordinated systems with full-selective S, I is sometimes disabled on the main incomer to extend selectivity to the breaker's full Icw rating. Disabling I is allowed only on breakers rated for the full short-circuit current as Icw — the E1.2 frames are 42 kA Icw, which matches the 42 kA Icu on most variants.

G — Ground-Fault

G detects residual current via the vector sum of the three phase CTs and the neutral CT. On TN-S systems, G is the front-line defense against arcing ground faults that can sit below the L pickup for hours. NEC Article 230.95 (and its IEC equivalent in 60364-4-41) effectively mandates G on service entrances above 1000 A on solidly-grounded wye systems at 480Y/277V — a detail that catches North American projects off-guard when they import Emax 2 specified to IEC defaults.

N — Neutral Protection

N is overload protection on the neutral conductor, set as a percentage of Ir (50%, 100%, 150%, 200%). Non-linear loads — VFDs, LED drivers, switching power supplies — produce triplen harmonics that sum on the neutral. In a data center MDB, neutral current can exceed phase current by 30–40%. We have measured 1.7 × Ir on the neutral of a fully-loaded UPS feeder. Without N, the neutral conductor cooks while the breaker stays happy.

How Do I Match Frame Size and Ekip Variant to Load Current?

The frame determines the maximum In; the Ekip determines the adjustable range. ABB Emax 2 frames go from E1.2 (250 A to 1600 A) up to E6.2 (5000 A to 6300 A). Within each frame, the rated current In is selected at order time and cannot be changed in the field — what you can change is Ir, the long-time pickup, between 0.4 and 1.0 × In.

So the procurement question is: what In should I order? The answer depends on continuous load current, ambient temperature, and future expansion. For full sizing methodology, the step-by-step Emax 2 sizing calculator walks through the derating factors. For trip unit selection, the rule is simpler: pick In so that your design continuous current sits between 0.7 and 0.9 × In. Below 0.7, you are wasting frame capacity. Above 0.9, you have no headroom for growth and the L curve becomes uncomfortably tight.

Real Procurement Example: 1200 A MCC Incomer

Suppose a continuous load of 1200 A on a motor control center incomer in a cement plant, ambient 45°C inside the switchroom, future expansion factor 1.20. Required Ir × In = 1200 × 1.20 = 1440 A. Options:

• ABB 1SDA070821R1 E1.2B 1250 Ekip Dip LI — In = 1250 A. Ir would need to be 1440/1250 = 1.15, which exceeds the maximum 1.0. Not suitable.
• ABB 1SDA070861R1 E1.2B 1600 Ekip Dip LI — In = 1600 A. Ir = 1440/1600 = 0.90. Sits at the upper edge but viable. However, LI alone may not give selectivity with downstream MCCBs.
• ABB 1SDA070981R1 E2.2B 1600 Ekip Dip LI — Same In, larger frame (E2.2). More headroom, higher Icw rating, but more expensive and physically larger.

For an MCC incomer, we would push the customer toward an Ekip Touch LSIG variant rather than Dip LI — the cost premium is roughly 15–20% but you gain selectivity, ground-fault protection, and energy metering. The Dip LI versions are appropriate where the breaker is the only overcurrent device on a feeder (e.g., a generator output to a single transformer) and ground-fault is handled by an external relay.

When Do I Need Ekip Touch vs Hi-Touch vs Dip?

This is where engineering judgment replaces the catalog. The functional difference between Touch and Hi-Touch on the ABB Emax 2 is not the protection (both do LSIG); it is the measurement class, the directional protections, and the firmware support for synchrocheck and load-shedding logic.

In practice, the decision tree we use on tender reviews looks like this. Is the breaker the utility interface, a generator breaker, or part of an automatic transfer scheme? Hi-Touch. Is it a main switchboard incomer or a tie breaker with measurement requirements for the BMS? Touch. Is it a sub-distribution feeder where another upstream device handles selectivity and metering? Dip LI or LSI is fine.

How Does Selectivity Drive the Trip Unit Choice?

Selectivity — the principle that only the breaker closest to the fault should trip — is the single biggest reason to upgrade from LI to LSIG. Engineers often overlook the fact that a 1600 A ABB Emax 2 with LI only is functionally a glorified MCCB; it cannot delay its trip, so any short circuit downstream that exceeds its instantaneous pickup will trip the main and drop the entire switchboard.

The S function changes that. With S set to, say, 200 ms with I²t-OFF, the upstream Emax waits 200 ms for the downstream device to clear. That window is enormous compared to MCCB clearing times (typically 20–40 ms at the upper limit of their breaking range), so selectivity is achieved by time grading.

Time Grading in Practice

A typical four-tier grading on a 480 V industrial site:

1. Utility/transformer secondary protection: 51 relay, 600 ms delay.
2. Emax 2 main incomer (Ekip Touch LSIG): S delay 400 ms, G delay 400 ms.
3. Emax 2 feeder (Ekip Touch LSIG): S delay 200 ms, G delay 200 ms.
4. Tmax XT or MCCB on motor feeder: instantaneous, ~30 ms total clearing.

Each step gives 200 ms of grading margin, which accommodates the 60–80 ms operating time of the Emax 2 (per the IEC 60947-2 type-test data) plus margin for CT error and measurement scatter. If you specified Dip LI on the feeder Emax, this scheme falls apart — there is no S to delay, so the feeder trips on instantaneous and races the MCCB.

For a deeper treatment of nuisance tripping caused by mis-applied LI settings, the article on ABB Emax 2 nuisance tripping root causes and fixes walks through three field cases.

What About Communication and Cybersecurity Modules?

Modern switchgear is rarely an island. Even on a small industrial project, the BMS or SCADA wants to read currents, voltages, and trip events from the ABB Emax 2. Ekip handles communication through plug-in modules that mount on the rear of the trip unit:

• Ekip Com Modbus RTU — RS-485, embedded in Touch and above.
• Ekip Com Modbus TCP — Ethernet, separate module.
• Ekip Com Profibus DP — for legacy Siemens-centric plants.
• Ekip Com Profinet — current Siemens standard.
• Ekip Com EtherNet/IP — Rockwell/Allen-Bradley environments.
• Ekip Com IEC 61850 — utility substations and data center power monitoring.
• Ekip Com Hub — gateway that exposes up to 10 breakers via a single Ethernet drop.

A common procurement mistake is ordering the breaker without specifying the communication module. The base Ekip Touch has Modbus RTU embedded but EtherNet/IP requires a separate add-on with its own part number. Specify it at the order stage; field-fitting is possible but means opening the switchboard, de-energizing the breaker, and running the Ekip Connect commissioning tool.

How Do I Handle Special Applications: Generators, Motors, Capacitor Banks?

The standard Ekip Dip and Touch on the ABB Emax 2 are tuned for distribution duty. Three application classes need different variants.

Generator Breakers

A generator breaker sees decaying short-circuit current — the fault current drops from sub-transient (X"d, ~6 × In) to transient (X'd, ~3 × In) to synchronous (Xd, ~1 × In) over a few hundred milliseconds. A standard L/S/I curve calibrated for utility-fed faults can fail to trip on a sustained generator fault because the current decays below the I pickup before the time delay expires. The Ekip Hi-Touch with the dedicated generator protection function (voltage-restrained overcurrent, 51V) handles this correctly.

Motor Feeders

Direct-on-line (DOL) motor starts produce inrush of 6–8 × FLA for 50–200 ms, then locked-rotor current of 6 × FLA for the acceleration period (1–10 s on large motors). A standard L curve set to FLA will trip on every start. The Ekip M variant has a thermal-image algorithm tuned to motor starting curves and includes phase-loss, locked-rotor, and jam protection. For a 400 kW DOL motor on a 690 V system, we always specify Ekip M Touch — the cost premium versus a separate motor protection relay is negligible and the integrated solution is easier to commission.

Capacitor Banks

Capacitor switching produces inrush transients that can reach 100 × Ir for less than a millisecond. Standard I settings will see this as a short circuit. Either disable I and rely on S with a 50 ms delay, or use the dedicated Ekip Touch with the capacitor switching profile (suppresses I for the first half-cycle).

Procurement Checklist: From Specification to PO

Here is the checklist we use internally before releasing a purchase order for an ABB Emax 2. It has saved us multiple times from ordering the wrong variant.

1. Frame and In: Confirm continuous load current, derating, future expansion. Confirm Ir × In ≥ I_load × k_future.
2. Icu vs Icw: Confirm prospective short-circuit current at the breaker location. For Emax 2 E1.2B, Icu = Icw = 42 kA at 415 V — adequate for most industrial sites. HigherIcu ratings (E1.2N at 65 kA, E1.2H at 66 kA, E2.2L at 130 kA) are available for utility interfaces and large transformer secondaries.
3. Protection function code: LI for simple feeders, LSI where time grading is needed but ground-fault is handled externally, LSIG for main incomers on solidly-grounded systems, LSIGN where neutral overload is a real risk (data centers, LED-heavy commercial loads).
4. Trip unit tier: Dip for sub-distribution, Touch for main distribution and MCC incomers, Hi-Touch for utility interface, generator paralleling, and IEC 61850 substations.
5. Communication: Specify the protocol module by part number. Modbus RTU is embedded in Touch; everything else is a separate order code.
6. Measurement class: Class 1 sufficient for BMS monitoring; Class 0.5 needed for revenue-grade billing or where the breaker is the metering point for a tenant in a multi-tenant building.
7. Auxiliary contacts and accessories: Shunt trip (YO), undervoltage release (YU), motor operator (M), spring-charged signaling (S33M2). These are independent of the Ekip but must match the supply voltage and signaling requirements.
8. Fixed vs withdrawable: Fixed (F) is cheaper and simpler; withdrawable (W) cuts maintenance time. The Ekip variant is the same; only the cassette differs.

Calculator: Long-Time Pickup and Frame Selection

The calculator below applies the Ir formula and recommends an ABB Emax 2 frame from the E1.2 and E2.2 families. It assumes a future expansion factor and validates that the resulting Ir falls within the 0.4–1.0 range. Use it as a first-pass tool; always cross-check with the full coordination study.

Common Field Mistakes and How to Avoid Them

After enough commissioning visits on ABB Emax 2 installations, the same handful of errors come up. Listing them is more useful than another spec table.

Mistake 1: Treating Ekip Dip as a Cheaper Touch

Engineers sometimes specify Dip LSI to save money, expecting they can dial in fine-grained settings later. Ekip Dip is binary: each DIP switch represents a discrete value. Ir steps are 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 — not the 0.01 steps available on Touch. If your coordination study calls for Ir = 0.83, Dip cannot deliver it. We saw this on a Saudi petrochemical project where the coordination study was redone twice before someone realized the Dip variant could not hit the required setting. The solution was a field swap to Touch, which cost the contractor four weeks of schedule.

Mistake 2: Ignoring the Neutral CT

On 4-pole breakers with G protection, the neutral CT is mandatory and must be ordered separately for the 3-pole + external N CT configuration. The G function calculates residual current as the vector sum of three phase CTs and the neutral CT. Without the N CT, the neutral current is treated as zero and any genuine ground fault on the neutral side is invisible to the protection. The ABB 1SDA070782R1 E1.2B 1000 Ekip Dip LSI 3p is a 3-pole device — fine for 3-phase 3-wire systems, not appropriate where neutral monitoring is required.

Mistake 3: Wrong Performance Class for the Site Isc

The performance class suffix (B, N, H, L, V) indicates the breaking capacity. B = 42 kA, N = 65/66 kA, H = 100/105 kA, L = 130 kA, V = 150 kA at 415 V. We have seen specifications that copy-paste E1.2B onto a 70 kA site, then face a non-compliance during the design review. The fix — moving to E1.2N — is a different part number with a different price and different lead time. Always verify Isc at the breaker location, including the contribution from large motors that backfeed the fault for the first cycle.

Mistake 4: Forgetting the Auxiliary Power Supply

Ekip Dip is self-powered from the main CTs above approximately 0.2 × In. Below that current, the trip unit has no power and cannot trip. For applications where the breaker may carry very low current for extended periods (standby gensets, redundant feeders) or where you want the display and communication to remain live with the breaker open, an auxiliary supply (Ekip Supply, 24 V DC or 110–240 V AC/DC) is required. This is independent of the trip unit tier; it is a separate accessory.

Mistake 5: Mis-specifying the Test Function

Ekip provides a "Test" function via the front USB port and Ekip Connect software. Some test procedures require Ekip T&P (Test & Programming) units — these are external test sets, not built into the breaker. The IEC 60947-2 type tests are factory; site testing is functional, not type. Confirming this distinction in the FAT/SAT plan prevents misunderstandings with witnesses.

Cross-Application Examples from the Field

Data Center MDB, 2N Topology, 2 × 2000 A Mains

For a Tier III data center in Dubai with two 2500 kVA transformers feeding redundant MDBs, we specified ABB 1SDA071021R1 E2.2B 2000 Ekip Dip LI as a placeholder during early design, then upgraded to E2.2B 2000 Ekip Touch LSIG with Modbus TCP for the final order. The Dip LI variant simply cannot meet the selectivity requirements with downstream 800 A feeder breakers. The detailed reasoning, including the coordination diagram, is covered in the ABB Emax 2 in Data Centers MDB design article.

Cement Plant MCC Incomer, 1600 A

For an Egyptian cement plant, the MCC incomer is fed from a 1500 kVA transformer with Isc = 35 kA at the busbar. We specified ABB 1SDA070861R1 E1.2B 1600 Ekip Dip LI initially but the coordination study flagged a selectivity gap with the largest downstream MCCB. Upgrading to E1.2B 1600 Ekip Touch LSIG resolved it, and the Touch unit's Modbus RTU interface allowed integration with the existing PLC-based monitoring without additional hardware.

Hospital Generator Output, 1000 A

For a hospital backup generator (1250 kVA, 400 V), generator protection requirements include voltage-restrained overcurrent (51V) and reverse power (32R). The ABB 1SDA070781R1 E1.2B 1000 Ekip Dip LI was rejected for this duty; the final spec was E1.2B 1000 Ekip Hi-Touch LSIG with the generator protection license enabled. The Hi-Touch's voltage measurement input (via external VTs or direct connection up to 690 V) makes the 32R and 51V functions native.

Commercial Office Tower, 800 A Sub-Distribution

For a 30-story office in Riyadh, sub-distribution panels at each floor receive 800 A feeders. Selectivity is handled at the main switchboard upstream; the floor breakers are essentially backup overcurrent protection. The ABB 1SDA070741R1 E1.2B 800 Ekip Dip LI is exactly right for this duty: cheap, reliable, no measurement overhead, and the LI function is sufficient because the upstream Touch LSIG handles selectivity.

Standards Reference: What the Codes Actually Say

For procurement managers reviewing specifications, the key clauses are:

• IEC 60947-2 §5.3.5 — Definition of overcurrent protective device characteristics (L, S, I, G).
• IEC 60947-2 §8.3.3.1.1 — Verification of overload tripping characteristics.
• IEC 60947-2 Annex F — Additional requirements for circuit breakers with electronic overcurrent protection.
• IEC 61557-12 — Performance measuring and monitoring devices (PMD); defines measurement classes 0.5, 1, 2.
• IEC 62053-22 — Electricity metering equipment, static meters, classes 0.5S and 0.2S.
• IEC 61850 — Communication networks and systems for power utility automation.
• IEEE C37.13 — Standard for low-voltage AC power circuit breakers used in enclosures (the North American equivalent specification).
• NEC Article 230.95 — Ground-fault protection of equipment, mandates GFP on solidly-grounded wye services > 1000 A at 480Y/277V.
• NEMA AB 4 — Guidelines for inspection and preventive maintenance of MCCBs (informative for ACB operators).

The Emax 2 is type-tested to IEC 60947-2 and UL 1066/ANSI C37.50 for North American market variants. ABB's published declaration of conformity (CE document 1SDH001317R0001) lists the harmonized standards covered. For a global procurement, verifying that the offered variant carries both IEC and UL certification matters when the same design is deployed across regions.

Comparison with Competitor Trip Units

Ekip is not the only modular trip unit on the market. Schneider's MicroLogic (on MasterPact MTZ) and Siemens' ETU (on 3WL) cover similar functional ground. The high-level comparison is in the Emax 2 vs MasterPact MTZ technical comparison; for trip unit selection specifically, the differences come down to firmware ecosystems and cyber-security posture. Ekip Hi-Touch with the IEC 61850 module is the strongest option in utility-grade applications. MicroLogic 6.0 X is comparable. ETU 800 is competitive but its Profinet-first orientation is a benefit only if the rest of the plant runs on Siemens.

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

For the broader product range, browse the full Air Circuit Breakers collection, the Miniature Circuit Breaker range for downstream protection, the Residual Current Device selection for additional ground-fault protection, and the Relay portfolio for external protection schemes.

Conclusion: Build the Part Number from the Application Down

Selecting the correct Ekip trip unit is not about memorizing the catalog. It is about reading the single-line diagram, the coordination study, and the system requirements, then mapping those onto a part number. The frame and In come from load current and short-circuit duty. The function code (LI, LSI, LSIG, LSIGN) comes from the selectivity scheme and ground-fault requirements. The trip unit tier (Dip, Touch, Hi-Touch) comes from measurement, communication, and special-protection needs. Get all three right and the breaker drops into the switchboard and works. Get one wrong and you end up swapping units in the field at three times the cost.

The discipline that separates senior engineers from juniors on this topic is not knowledge of the catalog — both have access to the same datasheets. It is the habit of working from the application down: what does the system need this breaker to do, what protection functions support that, what trip unit tier delivers those functions, what frame can host that trip unit at the required In. Build the part number in that order and the procurement decision becomes mechanical.

For the complete selection methodology covering frame sizing, accessories, switchboard integration, and lifecycle maintenance, work through the full ABB SACE Emax 2 Air Circuit Breaker Selection, Application and Maintenance Guide. For the upstream conceptual frame, the Air Circuit Breaker engineering guide covers the principles that apply across all ACB families. Both are kept aligned with the latest IEC 60947 amendments and reflect what we see on real projects across our customer base.