Tmax T4 and T5. T Generation, ABB Research Delivers Innovative technology.

The Tmax range of molded-case circuit-breakers for low voltage is now completed with two sizes covering up to 600 A. The T4 and T5 are the result of a comprehensive ABB research program: this is the first time such high performance have been achieved - 150 kA at 480 V AC, 100 kA at 600 V AC - in such a small breaker.

The Tmax T4 has a 250A frame size and overall dimensions of just 8.07 inches height, 4.07" depth and 4.13" length. This is the most compact circuit-breaker of this frame size with high performance at all voltage levels.

The Tmax T5 has a 600A frame size with the same depth and height and a length of just 5.51 inches. It has the same current breaking capacities as T4.

But the innovation introduced by Tmax T4 and T5 does not stop here: high limitation of the peak short-circuit currents with consequent reduction in the electrodynamic stresses in installations and high limitation of the specific let-through energy for better protection of the system. Thanks to these many characteristics, it is therefore possible to optimise sizing of cables, busbar ducts and relative supports, as well as all the coordinated apparatus on the load side.

Thanks to the patented device, the T4 and T5 circuit-breakers also stand out for the high levels of selectivity reached with other devices installed on the load side - a characteristic indispensable for molded-case circuit-breakers up to 600 A - with the aim of obtaining ideal coordination in low voltage installations.

The availability of a complete range of electronic and thermomagnetic trip units, is another distinguishing characteristic: the electronic PR221DS and PR222DS trip units are the ideal solution for protection of installations in alternating current and are characterised by the simplicity, precision and wide range of settings, whereas the TMA thermomagnetic trip units are ideal for protection of installations in direct current and guarantee the possibility of adjusting the protection threshold against overload and that of the protection against short-circuit. All the trip units are also interchangeable, with great benefit in terms of flexibility and reduction of stocks.

In the tradition of ABB, the Tmax series of molded-case circuit-breakers confirms the offer of solutions suitable for all requirements, thanks to development of the dedicated ranges: in fact, apart from the range for power distribution, a range of molded case switches and a range dedicated to motor control protection are available, thanks to the PR221DS-I instantaneous only trip units.

Double insulation, positive operation, behaviour to isolation and the high degrees of protection guaranteed in the different configurations are product characteristics which are also present in the T4 and T5 sizes, as is the case in the whole Tmax series, and which confirm ABB's constant commitment to the safety of its protection devices.

A complete range of common accessories for the two sizes is a further advantage of Tmax T4 and T5. The main news in this field is the availability, for the first time, of a stored energy motor operator. Finally, the proposal of connection terminals is extremely varied and complete, able to provide an adequate solution for all the different installation requirements.