Overview

One of the most portable moulded case circuit breakers (MCCB) available today, the TMAX XT from ABB can handle currents of up to 250 amps. The entire Tmax XT family, which carries IEC marking as well, is a widely known product. TMAX-XT features four main divisions: XT1, XT2, XT3, and XT4, which are only available in 3-pole and 4-pole configurations. It can be classified into fixed type, plug-in type, and withdrawable type depending on how it is installed.

All models are interchangeable between two trip units, thermal magnetic trip and electronic trip unit. The Tmax XT2 and Tmax XT4 models can be equipped with the cutting-edge, high-performance electronic trip unit Ekip, which is a new feature. How is Ekip put to use? When the green LED light is on, the trip unit is functioning normally; however, if there is another light present, it denotes that abnormal conditions are present. Another fascinating feature of this series is that the Ekip trip unit may exchange information or communicate with other devices by just being inserted into the moulded case circuit breaker with the Ekip Com module.

Tmax-XT Series Structural Characteristics

1.     Double insulation;

2.     Reliable operation;

3.     Isolation performance;

4.     Electromagnetic compatibility;

5.     Temperature and humidity environmental conditions;

6.     Anti-shock and vibration;

7.     Top or bottom line;

8.     ABB molded case circuit breakers have flexible installation positions, and can be horizontal, vertical or flat, without derating;

9.    ABB molded case circuit breakers do not need derating when installed at an altitude of less than 2,000 meters. If it exceeds 2,000 meters, the changes in atmospheric conditions will have a certain impact on equipment parameters, so derating methods are required to use.

Practical Applications of TMAX-XT Series

Power distribution protection- They can be installed and used throughout from low voltage distribution to the distribution of the electrical system due to the characteristics of high let-through energy, and also has the current limiting function to protect the load-side loop and equipment. As a thermal magnetic or electronic release is optional, then ABB's molded case circuit breakers can play the role of overload, short circuit, ground fault and indirect contact protection in the low-voltage distribution network.

Motor protection purposes- Whilst selection of a starting monitoring system for the motor, the safety and reliability of the solution are the most important to consider. Therefore, whether it is the motor itself or its power supply system, the starting stage is the most critical period. Even if it enters the normal operating state, it is still necessary to properly monitor and protect it to deal with any failures that may occur.It is now only necessary to configure an ABB moulded case circuit breaker with all protection and monitoring functions, and a contactor for start-stop motors.

Generator protection purposes- ABB's TMAX XT series of molded case circuit breakers can be equipped with thermal-magnetic trip units with very low magnetic tripping thresholds, effectively providing protection solutions for small generators and distribution networks with long cables, due to the relatively high cable impedance and a slight fault current occurs at the end of the cable. Therefore, the generator protection requirement is that the magnetic tripping threshold should be very low, usually about three times the rated current of the molded case circuit breaker, to reliably cut off the short-circuit current in the "transient zone" of the generator fault current decay curve.

Use of neutral wire protection- ABB's molded case circuit breaker TMAX XT series with neutral line protection is suitable for the occasions where the neutral line is overloaded due to harmonics or unbalanced loads and single-phase currents. Under these conditions, there will be a certain amount of current flowing through the neutral line, especially the third harmonic and related integer multiples of harmonics will be superimposed on the neutral line, resulting in the current of the neutral line being constantly rising, or even increasing. exceeds the phase current. Therefore, in an electrical system with a neutral line cross-section larger than the phase line cross-section, it is necessary to use a molded case circuit breaker with a neutral line protection function to provide appropriate protection.