There are several types of protection for dry-type transformer types .Depending on the capacity of the transformer, differential protection may be added as the main protection.General dry-type substation protection includes: quick-break, over-current, zero-sequence and other protections.
1. Dry-type transformer types quick-break protection
The quick-break protection is to overcome the long operating time limit of the protection device near the power supply end of the overcurrent protection, and the method of increasing the setting value to limit the operating range is used to protect the line.
There are three protection ranges: voltage quick-break protection, current quick-break protection, and transformer differential quick-break protection.
2. Overcurrent protection
Many electronic devices have a rated current, and it is not allowed to exceed the rated current, otherwise the device will be burned.Therefore, some equipment has a current protection module.When the current exceeds the rated current, the dry-type transformer equipment will automatically cut off the power to protect the equipment.
3. Zero sequence protection
Zero-sequence protection means that after a ground fault occurs in a large short-circuit current grounding system, there will be zero-sequence current, zero-sequence voltage and zero-sequence power, and these electrical quantities are used to form a collective name for the relay protection device that protects the ground short circuit.
The three-phase temperature of dry-type transformer is an important characteristic performance.Only when the three-phase temperature of dry-type transformer types is stable can its operation be safer and more stable.
Therefore, in the use and operation of dry-type transformer types, the three-phase temperature of dry-type transformer types needs to be balanced, but sometimes what is the reason for the large difference between the thermometers?
1. First of all, you must make sure that the temperature difference of 30 degrees you get is how to get it.The accuracy of the measurement method must first be sure that there is no problem, otherwise there will be no prerequisites.
2. If the three-phase load is balanced, the difference is 30 degrees.Then you have to check the external conditions of the transformer first, such as the heat dissipation environment, including ventilation, whether the thermometer temperature probe is plugged in, and so on.
3. If everything is normal, that is, there is a difference of 30 degrees, there is a problem.
4. First change the position of the temperature measuring probe of the thermometer (for example, change phase A to phase C).Of course the power should be turned off.I think most of the time it's the thermometer.
5. If there is still a problem, it is necessary to check the condition of the coil, which is difficult to deal with.It is necessary to test whether the insulation resistance of the transformer is qualified; measure the DC resistance of the transformer to see if there is a short circuit between turns.
6. The iron core of the transformer is not working properly.This is only possible in theory, but it is almost never encountered in fact.
The above is the analysis of the reasons for the large temperature difference between the three phases of the dry-type transformer.In the operation of the dry-type transformer types, we must pay attention to the transformer at the operating temperature to ensure the stability and safety of the dry-type transformer operation.