Circuit breaker type test
The purpose of organizing type test is to prove the ability and ensure the accuracy of rated characteristics of circuit breaker. Such tests are carried out in specially built test laboratories.
1. Mechanical test - This is a type test of mechanical capability involving repeated opening and closing of circuit breaker. The circuit breaker must be closed and opened at an appropriate speed and complete its assigned work and function without any fault.
2. Thermal test - conduct a thermal test to check the thermal behavior of the circuit breaker. Due to the rated current flowing through its pole under rated conditions, the circuit breaker under test experienced steady temperature rise. The temperature rise of the rated current is less than 800A, the normal current is not more than 40 °, and the temperature rise of the current normal value 800A and above is not more than 50 °.
3. Dielectric test - Perform these tests to check the power frequency and impulse voltage withstand capability. Conduct power frequency test on the new circuit breaker; The test voltage changes with the rated voltage of the circuit breaker. In the impact test, the circuit breaker adopts a specific value of impact voltage. Conduct dry-wet test for outdoor circuit.
4. Short circuit test - conduct sudden short circuit on the circuit breaker in the short circuit test laboratory, and understand the behavior of the circuit breaker during closing, during contact breaking and after arc extinction through the waveform diagram. The study of oscillogram especially refers to making and breaking current, symmetrical and asymmetrical re-trigger voltage, and the switchgear is sometimes tested under rated conditions.
Routine test of circuit breaker
Routine tests were carried out in accordance with the reference standards of Indian Engineering Services and Indian Standards. These tests are carried out at the manufacturer's premises. Routine test confirms that the circuit breaker functions normally. Routine tests confirm the normal function of the circuit breaker. Routine tests do not necessarily include complex equipment to ensure the normal operation of the circuit breaker. Some guidelines and recommendations for these tests include routine maintenance and verification of circuit breaker performance against the manufacturer's calibration curve. It is essential that these tests are carried out under stable conditions at appropriate temperatures, so that the data will not change. Some tests are listed below.
Preventive maintenance, inspection and test of circuit breaker
Preventive maintenance depends on the operating conditions of the circuit breaker. The preliminary inspection of CB (circuit breaker) will focus on the particles that pollute the operation inside the CB. Usually, the accumulated particles can be removed by turning the lathe on the "close" and "open" switches of the circuit breaker to remove the accumulated dust
Circuit breaker trip test
Whether there is a mechanical or electrical problem can be determined by analyzing the current consumed by the tripping coil during the operation of the circuit breaker. In many cases, such problems can be localized to help find the root cause. Optionally, monitoring the voltage of the trip power supply during operation can detect problems caused by the trip battery.
Insulation resistance test
For separate circuit breaker resistance test, it is better to disconnect the load and line conductor. If not separated, the test value will also relate to the characteristics of the connecting circuit. The resistance test is crucial to verify whether the insulation materials that make up the molded case circuit breaker work properly. In order to test the insulation resistance, an instrument called a megohmmeter is used. The megohmmeter applies a known DC voltage to a given wire within a given period of time to test the resistance in the insulation layer of that particular wire or winding. The use of voltage is critical because when the potential difference is not reported, the resistance checked with an ohmmeter may be different. It should also be noted that if the voltage you apply is too high to withstand the insulation,
Connection test
Connection testing is important to ensure that proper electrical connections are available and to identify signs of overheating indicated by color differences. It is important to correctly install the electrical connections to the CB to prevent and reduce overheating.
Contact resistance test
After a long time of use, the contacts in the CB will wear normally. A simple way to identify the weakening trace in the circuit breaker is to quantify the resistance of each pole of the circuit breaker. If there is too much millivolt voltage drop on the circuit breaker, it indicates that abnormal conditions (such as contact corrosion and pollution) in the CB are obvious. The contact resistance test is very important to determine whether the circuit breaker can still work normally.
Overload trip test
The overload tripping element of the circuit breaker can be tested by inputting 300% of the rated value of the circuit breaker into each pole of the circuit breaker to determine whether it will automatically open. The purpose of this is to ensure that the circuit breaker will operate or will not operate.
In the routine test, it is important to find out whether the magnetic feature works normally and trip the circuit breaker, rather than find the precise value of the instantaneous magnetic feature.