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High current generator temperature rise test

time:2021/1/22   source:华天电力  reading:234 time

The high current generator adopts an energy-saving high-permeability current booster, and is equipped with a digital stopwatch, which can meet time measurement. It has the characteristics of large output power, strong anti-overload ability, clear reading, flexible movement, etc., suitable for power system technology It is used for personnel inspection of current transformer, protection device and secondary circuit current test.


The temperature rise test of the large current generator is carried out by the large current generator. The test principle adopts the direct load method, that is, the electrical equipment is operated with actual load, and the various electricity and the temperature rise of each part are measured, and the temperature rise test is passed. To check the aging and damage of insulation materials and structural parts.


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1. Basic requirements for temperature rise test of large current generator


1. In order to make the measurement data of the temperature rise test accurate, the accuracy of the meter used to measure the electric quantity of the stator shall not be lower than 0.5 grade, and the accuracy of the meter used to measure the rotor shall not be lower than 0.2 grade.


2. The temperature rise test of the generator is a long-term thermal stability test. Each load test requires the rotor current to remain stable, and the variation range should not exceed 1% of the test current; the stator voltage, current and power should also be as much as possible To maintain stability and three-phase balance, the variation range should not exceed 3% of the test value. For this reason, the voltage automatic regulator should be cut off during the test, and the power factor should be maintained at the rated value.


3. During the test of the large current generator, the temperature θ0 of the cooling medium should be at or close to the rated value, and the temperature change of the cooling medium under each test load should not exceed 1K.


During the test, after stabilizing for 1h under each load, measure the measured power and temperature every 15min or 20min until stable. The so-called thermal stability refers to the change of the temperature of each part of the motor within 1h No more than 2K, the time required to reach thermal stability depends on the type and capacity of the motor, generally about 3-4h.


2. Preparations before the temperature rise test of the large current generator


1. Familiar with technical information


Before the high-current generator test, the test personnel should be familiar with the instructions and relevant technical data provided by the electrical equipment manufacturer, especially to understand the insulation mechanism of the equipment winding, the insulation class, the specified value of the allowable temperature (temperature rise) of each part, and the operating conditions And the buried position of the temperature measuring element.


2. Develop a test plan


The high-current generator will work with the relevant technicians of the power plant to formulate a temperature rise test plan for the high-current generator according to the situation it has mastered.


3. Measure the DC resistance of the stator and rotor windings


In the generator temperature rise test, the cold state DC resistance of the stator and rotor windings of the generator is a very important basic data in the temperature rise test. This is because when measuring the average temperature of the stator and rotor windings, it is necessary to use The cold resistance is used as the reference value to convert the average temperature of the winding, so its measured value directly affects the accuracy of the temperature rise test. Therefore, the quasi DC resistance value should be measured before the test.


Precautions for temperature rise test of high current generator:


1. The test work should not be less than two people, one person to operate, and one person to supervise the operation to ensure safety;


2. The shell must be grounded. Don't neglect to prevent personal safety accidents due to low voltage;


3. The wire from the secondary to the tested product should not be too long, the cross-sectional area should be sufficient, and the contact surface should be cleaned, otherwise the joint will heat up and the current will even fall below the rated value;


4. Check that the power supply has sufficient capacity before work, otherwise the power cord will become heated and the voltage drop will affect normal operation;


5. There should be no flammable materials at the work site, and sufficient fire extinguishing equipment should be prepared for the temperature rise test;


6. For the continuity (heating) test, there should be someone on-site, and regularly check the heating of the up-current source equipment, wires, and connectors, and make a record. Due to the change of the grid voltage, pay attention to adjust the TD to maintain the rated test current;


7. The test work shall comply with the relevant provisions of the electrical safety work regulations and formulate practical safety measures.

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