ABB Tmax XT MCCBs NZ | XT1 XT2 XT3 XT4 Ekip Trip Units

ABB Tmax XT Moulded Case Circuit Breakers

ABB / Tmax XT moulded case circuit breakers

XT1 and XT3 cannot take an electronic trip unit. Only XT2 and XT4 can. That is the real difference between the frames, and it is not visible in the current rating.

SACE Tmax XT is the ABB moulded case circuit breaker range. Four IEC frames up to 250 A, with the trip unit, terminals, version and accessories all selected separately.

Two tiers, paired by frame size

ABB positions the range as two pairs rather than four steps.

Frame	IEC size	Tier	Trip units	Versions
XT1	160 A	Standard	Thermomagnetic only	Fixed, plug-in
XT2	160 A	High performance	Thermomagnetic and electronic	Fixed, plug-in, withdrawable
XT3	250 A	Standard	Thermomagnetic only	Fixed, plug-in
XT4	160 and 250 A	High performance	Thermomagnetic and electronic	Fixed, plug-in, withdrawable

ABB describes it directly: XT1 and XT3 for standard installations, XT2 and XT4 for technologically advanced installations.

Three consequences worth knowing

An XT1 cannot be given an Ekip electronic trip unit. If an application needs adjustable short time delay, earth fault protection or metering, it needs an XT2 regardless of current.

Only XT2 and XT4 come in a withdrawable version. If maintenance access matters, that decides the frame.

The insulation voltage differs. XT1 and XT3 are rated Ui 800 V; XT2 and XT4 are rated Ui 1000 V.

So an XT1 and an XT2 are both 160 A frames and are not equivalent devices.

The breaking capacity is a letter

This is the part of the designation people miss, because it looks like a model suffix.

Frame	Breaking capacity classes available
XT1	B, C, N, S, H
XT2	N, S, H, L, V
XT3	N, S
XT4	N, S, H, L, V

The letters run from lower to higher breaking capacity: B, C, N, S, H, L, V.

So an XT2N and an XT2V are the same frame with very different fault performance. Substituting down is a protection decision, not a parts decision, and it depends on the prospective fault current at that point in the installation.

Read the letter off the existing breaker and match it. If you need to change it, that belongs with whoever did the fault level study.

ABB notes the H, L and V classes on the UL XT2 and XT4 are current limiting.

IEC and UL frame sizes are different

A real trap on imported machinery.

Frame	IEC rating	UL rating
XT1	160 A	125 A, to 480 V delta
XT2	160 A	125 A, to 600 V
XT3	250 A	225 A, to 480 V delta
XT4	160 and 250 A	250 A, to 600 V

The same frame is rated differently under the two standards. An XT1 is a 160 A frame in an IEC catalogue and a 125 A frame in a UL one.

The UL range also extends further: XT5 at 600 A, plus XT6, XT7 and XT7M.

UL interrupt ratings include 65 kA at 480 V on the XT1, 200 kA at 480 V and 42 kA at 600 V on the XT2, 35 kA at 480 V on the XT3, and 200 kA at 480 V with 100 kA at 600 V on the XT5.

If a machine arrived from North America, check which standard the nameplate is quoting before matching a rating.

Common ratings across the range

Item	XT1	XT2	XT3	XT4
Poles	3, 4	3, 4	3, 4	3, 4
Rated service voltage Ue, AC	690 V	690 V	690 V	690 V
Rated service voltage Ue, DC	500 V	500 V	500 V	500 V
Rated insulation voltage Ui	800 V	1000 V	800 V	1000 V
Impulse withstand Uimp	8 kV	8 kV	8 kV	8 kV

ABB rates the XT3 for 25,000 mechanical operations.

Trip units

Thermomagnetic

Type	Frames
TMD, TMA	XT1, XT3
TMD, TMF	XT2, XT4
MF, MA	Motor protection, all four frames, three-pole only

The fixed and adjustable split depends on current and standard. On IEC XT2 and XT4, ABB specifies adjustable overload with fixed instantaneous through 32 A, and fully adjustable thermal magnetic at 40 A and above.

On UL, the XT2 is thermal magnetic fixed through 70 A and adjustable at 80 A and higher.

So a small frame breaker may have no adjustment at all. Worth knowing before someone goes looking for a dial that is not there.

Ekip electronic

Ekip type	Protection functions
Ekip I	Instantaneous
Ekip LS/I	Long time, short time, instantaneous
Ekip LSI	Long time, short time, instantaneous
Ekip LSIG	Long time, short time, instantaneous, earth fault
Ekip E-LSIG	As LSIG plus energy metering. XT4 only
Ekip M	Motor protection. XT2 and XT4, three-pole

The letters are the protection functions. L is overload, S is short time delay, I is instantaneous, G is earth fault, E is energy metering.

G is the one that matters most on a substitution. An Ekip LSI has no earth fault protection and an Ekip LSIG does. If the installation relies on it, the letter is not optional.

Ekip rated currents

Frame	In values available
XT2	10 A, 25 A, 63 A, 100 A, 160 A
XT4	40 A, 63 A, 100 A, 160 A, 250 A

Note the XT4 does not go below 40 A on Ekip. For a smaller electronic breaker you need the XT2.

Trip units are interchangeable

ABB states the trip units are interchangeable right from the smallest frames, and that Ekip units are interchangeable across the range.

So a trip unit failure does not always mean a new breaker. That is worth checking before quoting a complete replacement, and it is a meaningful saving on a large frame.

Tell us whether you need the breaker, the trip unit, or both.

Motor protection settings

The MF and MA magnetic-only trip units are used with a thermal relay and a contactor, and the instantaneous threshold differs by frame.

Frame	Instantaneous threshold I
XT1	In 6.3 A or below: adjustable 4 to 11 x In. Above 6.3 A: adjustable 3 to 11 x In
XT2	In 12.5 A or below: fixed at 14 x In. Above 12.5 A: adjustable 6 to 14 x In
XT3	Adjustable 6 to 12 x In
XT4	Adjustable 5 to 10 x In

The magnetic setting is made by turning a cursor on the front of the release.

Note the XT2 threshold is fixed at 14 x In below 12.5 A. No adjustment available, and 14 x In is high. On a small motor that is deliberate, to ride through starting inrush.

Ekip M motor protection

Available on XT2 and XT4 in three-pole. Protections include:

Function	Setting
Rotor locking, R	OFF, or adjustable 3 to 9 x I1
Instantaneous short circuit, I	Adjustable 6 to 13 x In
Phase loss, U	Trips if one phase falls below 0.1 x In while another exceeds 0.25 x In

The phase loss function is worth understanding. It does not simply watch for a missing phase. It compares them, tripping when one is essentially dead and another is still carrying load. That is what a single phasing motor actually looks like.

A fixed green LED indicates correct trip unit operation.

Generator protection needs a low magnetic threshold

A useful piece of engineering from the ABB catalogue that explains a specification people query.

Generator protection requires a low magnetic threshold, typically about three times the breaker's rated current, so as to cut the short circuit current in the transient zone of the decrement curve.

The same reasoning applies to distribution networks with very long cables, where the end of line fault current is low.

So a generator or long-cable circuit needs a lower trip threshold than an equivalent mains circuit, because the available fault current is smaller and a standard setting may never see it.

If a breaker is specified with an unusually low magnetic setting, that is usually why. Do not raise it to stop nuisance tripping without understanding what it was set for.

Accessories and options

Item	Notes
Ekip TT	Trip test unit. Allows trip test, LED test and signalling
Modbus communication module	For integration into a supervision system
Keylocks and padlocking	Wide range of options
Terminals	FC CuAl and others. Additional options available as loose accessories on IEC versions
Switch disconnector versions	Available across the range

The Ekip TT lets you prove a breaker trips without creating a fault. On a plant with a testing regime that is the difference between a documented test and a hopeful assumption.

Two and four pole ordering notes

From the ABB selector, worth knowing before quoting.

The two-pole version is available only as a complete circuit breaker with a TMF trip unit, though the trip units remain interchangeable afterwards.

Four-pole versions also have ordering restrictions. Tell us the pole count and we will confirm what configuration is actually orderable.

Where Tmax XT sits in the ABB range

Useful when a breaker is being replaced by something a size up or down, because the three tiers are ordered very differently.

Range	Typical duty	How it is ordered
S200 MCB	Final circuits	Selected. One part number
Tmax XT	Up to 250 A IEC	Configured. Frame, breaking capacity, trip unit, terminals
Emax, Emax 2	Main incomers and large feeders	Configured, and a withdrawable unit is two parts

The step up to Emax adds one thing that catches people. A withdrawable Emax is a moving part and a fixed part, and ordering the moving part alone leaves you with a breaker and nothing to plug it into.

See our Emax and Emax 2 page for how those are put together, and the S200 page for the smaller end.

What to send us

The frame. XT1, XT2, XT3 or XT4.

The breaking capacity letter. B, C, N, S, H, L or V.

The pole count.

The trip unit type and its In rating. TMD, TMA, TMF, MF, MA or an Ekip variant.

Fixed, plug-in or withdrawable.

Whether it is an IEC or UL device, since the frame ratings differ.

Whether you need the breaker, the trip unit, or both.

A photograph of the front covers most of that. The frame, breaking capacity and trip unit are all marked.

What we can supply

Current production. Tmax XT across all frames, breaking capacities, trip units and versions, plus terminals, auxiliaries, Ekip TT and communication modules. Quoted with a delivered lead time.

Trip units separately. If the breaker is sound and the trip unit has failed, that is the cheaper order.

Earlier Tmax and legacy SACE ranges. Surplus and tested used.

Send us your type designations

Include the breaking capacity letter, because an XT2N and an XT2V are the same frame with very different fault performance. 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, SACE, Tmax, Emax and Ekip are trademarks of ABB Ltd. All trademarks, brand names and type designations 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 electrical design advice. Breaking capacity and trip settings depend on the installation and belong with whoever is responsible for its protection design.