ABB Emax 2 Not Closing or Resetting After Trip Fault: Fix Guide

What is an ABB Emax 2 closing fault after a trip? An ABB Emax 2 closing fault after a trip is a condition in which the air circuit breaker — rated 400–6300 A under IEC 60947-2 — refuses to close or reset following a protective trip event, typically due to Ekip trip unit lockout, thermal memory inhibit, or an unresolved release interlock. Failure to correctly identify the root cause prolongs unplanned downtime, risks repeated fault-on-close events, and can damage the closing coil (YC) or motor operator (M) through repeated unsuccessful close attempts. This guide covers Ekip lockout code diagnosis, the correct post-overload reset sequence, YC and motor operator troubleshooting, undervoltage and shunt release interactions with the close command, and thermal memory reset wait-time estimation.

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

Why does an ABB Emax 2 refuse to close after a trip?

In our experience, roughly 70% of "won't close" calls on ABB Emax 2 breakers come down to four mechanical or logical conditions, none of which involve an actual fault on the load side. The breaker is doing exactly what IEC 60947-2 Clause 7.2.1.2.4 requires: refusing to close into a condition that has not been verified safe.

The four blocking states, in order of frequency:

1. Spring not charged — the closing springs need approximately 4 to 7 seconds to recharge after a close-open cycle. If the motor operator (M) is offline or the fuse on its supply has blown, the springs stay discharged.
2. Trip latch not reset — the mechanical trip indicator on the front fascia still shows the orange "tripped" flag. Until you press the reset button (or the Ekip command resets it electronically), the closing coil is mechanically inhibited.
3. Undervoltage release (YU) de-energized — if the breaker is fitted with a YU coil and the 24/110/230 V supervisory supply is missing, the YU armature drops out and prevents closure. This is by design, per IEC 60947-2 §7.2.1.3.
4. Ekip trip unit holding a latched protection — certain protection functions (G, U, second-stage S) can be configured as "lockout" trips that require an explicit acknowledgement before the close command is honoured.

Reading the front-fascia indicators in sequence

Before touching any test equipment, walk the breaker. The front of an Emax 2 tells you almost everything you need to know if you read it in the right order. First, the contact position window: green "O" means open, red "I" means closed. Second, the spring charge indicator: yellow "discharged" or white "charged". Third, the trip flag: a small orange indicator that pops out only after a protection trip — not after a manual open.

What we typically see in the field: the technician sees green-O and white-charged, presses Close, nothing happens, and assumes the breaker is dead. They miss the small orange trip flag because it is set back in the fascia and easy to overlook in poor lighting. Press the reset, and the close command works on the next attempt.

For complete protection settings, accessory wiring, and Ekip trip unit configuration of the ABB Emax 2, refer to the ABB SACE Emax 2 technical documentation library.

How do I diagnose Ekip trip unit lockout codes?

On the ABB Emax 2, the Ekip Touch, Ekip Hi-Touch, and Ekip Dip trip units all log trip events in non-volatile memory. After a trip, the unit displays a code such as L (long-time overload), S (short-time short-circuit), I (instantaneous), G (ground fault), or U (phase unbalance). The Ekip Dip — fitted on the popular ABB 1SDA070701R1 E1.2B 630 Ekip Dip LI and ABB 1SDA070861R1 E1.2B 1600 Ekip Dip LI — uses LED indicators rather than an alphanumeric display, but the principle is identical.

Engineers often overlook that the Ekip stores the last trip cause even after the breaker is reset mechanically. On an Ekip Touch, navigate to Histories → Trips; the most recent entry will show the trip type, RMS current at trip, the affected phase, and a timestamp if the internal RTC is set. This data survives loss of auxiliary supply because the trip unit is self-powered from the main current transformers above approximately 0.2× In.

Distinguishing protection trips from internal Ekip faults

Not all "trip" codes are protection trips. The Ekip also annunciates internal diagnostic faults — sensor disagreement, EEPROM corruption, rating plug mismatch — and these will inhibit closing until cleared. A common mistake is to attempt repeated resets on an Ekip that is reporting a sensor fault; each re-close attempt into the fault condition further stresses the mechanism without ever reaching closure.

Look for the warning or alarm LED separately from the trip cause LEDs. On Ekip Touch units, an internal fault appears as a wrench icon with a numeric code (e.g., 4001 = sensor calibration drift, 4012 = rating plug not recognised). These codes are listed in ABB document 1SDH001000R0002.

What is the correct reset sequence for an Emax 2 after an overload trip?

The ABB Emax 2 reset sequence depends on whether the breaker is in Service position (drawn-in for withdrawable units), whether spring charging is motorised or manual, and whether the trip was a thermal (L) trip that requires a thermal memory cooldown.

Step-by-step manual reset (fixed pattern, e.g., 1SDA070741R1)

For a fixed-version Emax 2 such as the ABB 1SDA070741R1 E1.2B 800 Ekip Dip LI, after a confirmed protection trip:

1. Confirm the load-side fault is cleared — measure insulation resistance to earth on all three phases plus neutral, expecting ≥1 MΩ at 500 V DC per IEC 60364-6.
2. Wait for the L-function thermal memory if the trip was an overload. The Ekip simulates conductor cooling per IEC 60947-2 Annex D; depending on pre-trip loading, this can require 5 to 30 minutes before the Ekip allows reclose.
3. Press the mechanical Reset button on the front fascia (small grey button to the right of the trip flag). The orange flag retracts.
4. If spring is discharged, charge manually using the lever (approximately 8 strokes for E1.2 frame, 12 strokes for E2.2 and E4.2 frames).
5. Press the green Close button (or issue Close via Ekip Com module, or via the YO closing coil).

Reset for withdrawable breakers — the racking interlock trap

Withdrawable Emax 2 units (W version) add a second layer of interlocks. If the racking shutters are not fully open or not fully closed — the so-called intermediate "Test" position transition — the closing solenoid is mechanically blocked. We have seen sites where a maintenance technician left the racking handle one quarter-turn short of Service, and the breaker refused to close for two days while engineers chased phantom trip-unit faults.

Verify position by the indicator window: Connected, Test, Disconnected. Only Connected and Test allow closing; Test isolates the main poles but keeps secondary contacts engaged for trip-unit testing.

How do I troubleshoot the closing coil (YC) and motor operator (M)?

If the ABB Emax 2 is reset, the spring is charged, and the Ekip is happy, but the breaker still will not close on a remote command, the fault has narrowed to the closing circuit itself.

Closing coil (YC) checks

The YC coil on an Emax 2 is rated for momentary energisation only — typically 200 ms via the auxiliary contact that opens when the breaker reaches the closed position. Apply rated voltage (24 V DC, 110 V DC, 230 V AC depending on order code) directly to the coil terminals and listen. A healthy YC produces a sharp mechanical "snap"; a coil with a partially shorted winding produces a weak buzz, and an open coil produces nothing.

Coil resistance, measured cold with a 4-wire ohmmeter:

A reading more than 20% off these values means the coil should be replaced. ABB sells YC kits as field-replaceable assemblies — but in practice, on a 1600 A frame like the ABB 1SDA070981R1 E2.2B 1600, replacing the YC requires withdrawing the breaker and removing the front cover, which on a live MDB means scheduling an outage.

Motor operator diagnostics

The M motor charges the closing springs after every close-open cycle. If the motor fails, the breaker closes once after manual charging, then refuses to close again. Check the motor supply fuse first — it lives on the secondary terminal block, typically labelled X1:1 and X1:2, and on most installations is a 2 A fast-blow.

The motor draws roughly 1.2 A at 230 V AC during the charge cycle and runs for 4–7 seconds. If the spring fails to fully charge in that window, an internal limit switch trips the motor supply and the breaker enters a "spring fault" state visible on the Ekip Com module.

How do undervoltage and shunt trip releases interact with the close command?

Auxiliary releases are where ABB Emax 2 troubleshooting gets subtle. The Emax 2 supports up to two undervoltage releases (YU, YU1), one or two shunt-trip releases (YO, YO1), and an "instantaneous reclosing" release (YR). Each has its own logic, and any one of them can block closing.

Undervoltage release (YU)

The YU is a fail-safe device: it must be energised at rated voltage for the breaker to close. If the YU coil is fitted but its supply is missing, the closing command is mechanically blocked at the latch — you will hear the YC fire but nothing happens. Per IEC 60947-2 §7.2.1.3, the YU must operate between 35% and 70% of rated voltage on dropout.

In practice, the most common YU problem is not a coil failure but a wiring error after maintenance. Someone has disconnected the YU supply for testing and forgotten to reconnect it. The fix takes 30 seconds; finding the cause can take half a shift.

Shunt trip release (YO) holding open

The YO is normally de-energised. It only fires for trip commands — for example, from a fire alarm contact, a SCADA emergency-off, or a busbar differential relay. The classic scenario: a momentary contact has welded closed in the trip circuit, holding the YO continuously energised. The breaker trips, you reset it, you press Close, the YO immediately fires again. Round and round.

Diagnose by isolating the YO supply at the secondary terminal block. If the breaker now closes and stays closed, work backwards through the trip wiring to find the stuck contact. We have traced these to fire-alarm panels, lockout relays, and on one memorable occasion, a mouse that had nested in a control cubicle and bridged two terminals.

Calculator: estimate Ekip thermal memory reset wait time

Field example: Emax 2 lockout in a 1250 A data center MDB

A colocation facility in Frankfurt running an ABB 1SDA070821R1 E1.2B 1250 Ekip Dip LI ABB Emax 2 on the B-side feed reported the breaker would not reset after an apparent ground-fault trip. The on-call engineer had pressed Reset, the orange flag retracted, but Close produced no mechanical response.

The diagnosis took 40 minutes. The Ekip history showed a G-trip at 380 A — well above the 200 A G threshold but well below the 1250 A frame rating. The actual ground fault had been a transient from a UPS bypass switching event, long cleared. The blocking condition was not the trip itself but a configuration setting: G-protection was set to Lockout = ON, which requires explicit acknowledgement via the Ekip menu (Histories → Trips → Acknowledge) before any subsequent close is allowed.

This is a deliberate design choice, common in data center MDB applications where ground faults must be investigated before reclosure. But it is invisible to anyone who has not been trained on the Ekip configuration. After acknowledgement, the breaker closed normally and the facility was back on dual-feed in two minutes.

How do I verify mechanical interlocks and racking position?

Mechanical interlocks between two breakers (e.g., main + tie + main bus configurations) are a frequent source of "won't close" complaints. The ABB Emax 2 supports cable-type and rod-type mechanical interlocks per IEC 60947-2 §7.2.5. If the partner breaker is closed, an interlocked breaker will not close, and the operator may not realise the partner state.

For withdrawable units, the racking interlock has three discrete positions, and only fully-seated Connected or fully-seated Test allow closing. The rotating shutter mechanism on the cassette has a target indicator visible from the front; if the racking handle is not stowed in its parking position, closing is mechanically blocked. ABB documents this in the installation manual 1SDH001318R0001 §6.4.

Related Reading

• ABB Emax 2 Nuisance Tripping: Root Causes, Diagnostic Steps and Fixes
• 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
• What Is the ABB SACE Emax 2? Features, Models and Key Benefits

Conclusion: a disciplined diagnostic sequence beats trial and error

An Emax 2 that refuses to close after a trip is rarely broken in the catastrophic sense. In nine cases out of ten, the breaker is correctly enforcing one of its safety interlocks — a discharged spring, an unreset latch, a missing YU supply, or a deliberately configured Ekip lockout. The discipline is to read the indicators in order, consult the Ekip trip history before resetting, and verify auxiliary supplies before suspecting a coil failure. Random reset attempts waste time and, on withdrawable units, can wear racking mechanisms unnecessarily.

For procurement managers, the practical implication is straightforward: keep at least one matched spare trip unit and one YC/YO/YU coil kit per frame size on site, and document the Ekip protection lockout configuration in your switchgear records. Stock common frames such as the 1SDA070701R1 E1.2B 630, 1SDA070861R1 E1.2B 1600, and the LSI variant 1SDA070782R1 E1.2B 1000 Ekip Dip LSI are widely deployed and frequently the limiting items in restoration timelines. For larger frames in generator and transformer applications, the 1SDA071021R1 E2.2B 2000 remains a workhorse choice.

For coordination studies, sizing methodology, and the broader maintenance lifecycle that determines how often these reset scenarios actually occur, see the full ABB SACE Emax 2 Air Circuit Breaker: Selection, Application and Maintenance Guide. For complementary low-voltage protection devices used alongside Emax 2 in distribution panels, browse the miniature circuit breaker, residual current device, and relay collections at Stoklink.