One size fits all in novel MCCB range

An ABB Automation Tech (LV Products) product story

Edited by the Engineeringtalk editorial team Dec 24, 2003

A new generation of Tmax moulded case circuit breakers is designed to cover virtually any low-voltage application up to 250A in a range of just three frame sizes with a common frame depth.

ABB's new generation of Tmax moulded case circuit breakers (MCCBs) is designed to cover virtually any low voltage application up to 250A in a range of just three frame sizes with a common frame depth of 70mm which allows standardisation of fixing supports.

The Tmax range has been developed to combine a very high level of performance, comparable to larger sized circuit breakers, with reduced overall dimensions, easy installation and increased safety for installers and operators thanks to the double insulation which is a first on this size of circuit-breaker.

All three frame sizes feature an adjustable thermal threshold, while the mid-size T2 unit is also available with an electronic release for even greater flexibility.

Tmax T1 is the most compact 160A MCCB on the market.

It has a short-circuit breaking capacity up to 36kA at 415V AC and its high performance when used as a general switchboard circuit breaker means that the short-circuit withstand control tests (IEC60439-1) do not have to be carried out.

All the installer has to do is follow ABB's instructions to obtain a certified AS (Standard Apparatus) or ANS (Nonstandard Apparatus) switchboard.

In addition, ABB has developed a single-pole circuit breaker, Tmax T1 1P, able to cover currents up to 160A at service voltages up to 240V AC.

It is identical to the standard T1 with the exception of its width, which is the 24.5mm size typical of single-pole circuit breakers.

It can therefore be installed in distribution switchboards using a base plate, or even side by side with other Tmax circuit breakers.

Tmax T2 is the only 160A circuit breaker on the market which is capable of offering a short-circuit breaking capacity of 85kA at 415V AC in such compact dimensions.

This is made possible by an advanced double breaking system with forked moving contacts.

In addition to the adjustable thermomagnetic release common to the Tmax series, the T2 also offers an optional electronic release that provides a large and varied selection of setting curves to broaden the available selectivity functions for even greater flexibility.

Tmax T2 also facilitates co-ordination for motor protection up to 45kW at 415V AC.

Extensive research and development has enabled ABB to create Tmax T3 as the most compact 250A MCCB on the market.

Thanks to the same 70mm frame depth as the T1 and T2, the T3 can use the same standardised fixing supports.

This means that everything from a 250 to 50A circuit breaker can now be installed on a DIN EN50022 rail.

Tmax T3 also facilitates co-ordination for motor protection up to 90kW at 415V AC.

An important feature across the Tmax range is a new design of arcing chamber that rapidly reduces peak currents.

Both fixed pattern circuit circuit breakers and the fixed base plug-in versions have the same terminals and the Tmax is compatible with the Unifix H flexible distribution system for rapid assembly.

Cutouts are standardised at 45mm for all three frame sizes while a patented flange eliminates the need for drilling and fixing screws.

A new range of residual current protection devices has been designed to complement the Tmax series.

The three-pole and four-pole releases are designed and constructed to optimise space within the switchboard and can be simply and easily coupled to the circuit breaker with no need for workshop fitting.

Up to three changeover auxiliaries plus one alarm signal auxiliary can be fitted internally to the Tmax circuit breakers.

A new range of unified and standardised accessories has been developed to complement the Tmax design including a new door mounted rotary handle and service releases as well as a variety of mounting solutions.