The purpose of organizing the type test is to prove the ability and ensure the accuracy of the rated characteristics of the circuit breaker. Such tests are carried out in specially built testing laboratories.
1. Mechanical test - this is a type of mechanical capability test involving repeated opening and closing of circuit breakers. The circuit breaker must be closed and opened at an appropriate speed and complete its assigned work and functions without any failure.
2. Thermal test - perform a thermal test to check the thermal behavior of the circuit breaker. As the rated current flows through its pole under rated conditions, the circuit breaker under test experiences steady-state temperature rise. The temperature rise of rated current is less than 800A, the normal current is not more than 40 °, and the temperature rise of current normal value 800A and above is not more than 50 °
3. Dielectric tests - perform these tests to check the power frequency and impulse voltage withstand capability. Power frequency test on the new circuit breaker; The test voltage changes with the rated voltage of the circuit breaker. In the impulse test, the circuit breaker adopts the impulse voltage of a specific value. Conduct dry and wet test for outdoor circuits.
4. Short circuit test - conduct a sudden short circuit to the circuit breaker in the short circuit test laboratory, and understand the behavior of the circuit breaker during closing, contact opening and arc extinguishing through the waveform diagram. The study of oscillogram especially refers to the making and breaking current, symmetric and asymmetric re triggering voltage, and the switchgear is sometimes tested under rated conditions.
Routine test of circuit breaker
Routine tests are 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 test to 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 verifying whether the performance of the circuit breaker conforms to 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 testing of circuit breakers
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 internal work of CB. The accumulated particles can usually be removed by turning the lathe on the "off" and "on" switches of the circuit breaker to remove the accumulated dust.
Circuit breaker trip test
By analyzing the current consumed by the tripping coil during the operation of the circuit breaker, it can be determined whether there is a mechanical or electrical problem. In many cases, such problems can be localized to help find the root cause. Alternatively, monitoring the voltage of the tripping power supply during operation can detect problems caused by the tripping battery.
Insulation resistance test
For separate circuit breaker resistance tests, the load and line conductors are preferably disconnected. If not separated, the test value will also relate to the characteristics of the connected circuit. The resistance test is very important to verify whether the insulating material constituting the molded case circuit breaker is working properly. In order to test the insulation resistance, an instrument called a megger is used. The megger applies a known DC voltage to a given wire within a given period of time to test the resistance in the insulation on that particular wire or winding. It is important to use voltage because the resistance checked with an ohmmeter may be different when the potential difference is not reported. It should also be noted that if the voltage you apply is too high for the insulation to withstand
Connection test
Connection tests are important to ensure that appropriate electrical connections are available and to identify signs of overheating represented by color differences. It is important that the electrical connections are correctly installed to the CB to prevent and reduce overheating.
Contact resistance test
After long-term use, the contacts in CB will wear normally. A simple method 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 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 open automatically. The purpose of this is to ensure that the circuit breaker will operate or not operate.
In routine tests, it is important to find out whether the magnetic characteristics work properly and trip the circuit breaker, rather than finding the exact value of the instantaneous magnetic characteristics.
