It can be mainly divided into 4 types, including XT1, XT2, XT3, XT4. The maximum frame current can reach 250A. At the same time, the number of poles of the ABB MCCB Tmax XT series can be divided into 3 poles and 4 poles. According to the installation method It can be divided into fixed type, plug-in type and withdrawable type. All models can be equipped with a new generation of thermal magnetic trip unit or electronic trip unit protection device, and at the same time, the two trip units can be interchanged. ABB molded case circuit breakers are suitable for motor protection, energy metering, Neutral protection, generator protection and any other use.
It is also equipped with a new high-performance electronic trip unit Ekip, which can be installed on the Tmax XT2 and Tmax XT4 model molded case circuit breakers for use. When the green LED light is always on, it means that the trip unit is in normal operation. In addition, all Ekip trip units are specially equipped with another LED light, which is mainly used to indicate abnormal conditions of all protection functions. If you want the Ekip trip unit to communicate with other equipment or exchange information, you only need to insert the Ekip Com module into the molded case circuit breaker.
I.ABB Molded Case Circuit Breaker Tmax XT Series Nameplate Instructions
The characteristics of the circuit breaker are marked on the nameplates on the front and side of the case, as shown in the figure below.
- Circuit breaker name and performance level*;
- In: rated current*;
- Uimp: rated impulse withstand voltage*;
- Ui: insulation voltage*;
- Ics: rated operating short-circuit breaking capacity*;
- Icu: rated ultimate short-circuit breaking capacity*;
- Ue: rated working voltage*;
- Isolation performance*;
- Reference standard IEC60947-2*;
- Serial number;
- Anti-counterfeiting signs;
- Test button;
- CE mark;
- Use category;
- Reference standard NEMA-AB1;
Note: * means according to IEC60947 standard.
II.ABB Molded Case Circuit Breaker Tmax XT Series Structural Characteristics
- Double insulation;
- Reliable operation;
- Isolation performance;
- Electromagnetic compatibility;
- Temperature and humidity environmental conditions;
- Anti-shock and vibration;
- Top or bottom line;
- ABB molded case circuit breakers have flexible installation positions, and can be horizontal, vertical or flat, without derating;
- 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.
III.The scope of application of ABB molded case circuit breaker Tmax XT series
- Power distribution protection
From the low-voltage main distribution cabinet to the distribution box of the electrical system, it can be installed and used. Because it has the characteristics of high let-through energy, and also has the current limiting function to protect the load-side loop and equipment. If 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
When selecting and manufacturing a starting monitoring system for an electric motor, the safety and reliability of the solution are important aspects 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, so as to deal with it in time. 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. When selecting operating and protective devices, several factors must be considered, including the electrical characteristics of the motor (type, rated power, efficiency, power factor), the type of starting and the electrical diagram, and finally the power grid where the motor is located. Part of the fault current and voltage, etc.
- 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.
