Causes and solutions of photovoltaic system switch tripping
In the photovoltaic system, the electrical switch has two main functions: one is the electrical isolation function. During installation and maintenance, the electrical connection between the photovoltaic module, the inverter, the power distribution cabinet and the power grid is cut off to provide the operator with a In a safe environment, this action is actively implemented by the operator; the second is the safety protection function. When overcurrent, overvoltage, short circuit, overtemperature and leakage current occur in the electrical system, the circuit can be automatically cut off to protect the safety of the person and equipment This action is realized automatically by the switch. Therefore, if the switch trips in the photovoltaic system, the reason is that the switch may have over-current, over-voltage, over-temperature, and leakage current. The following is a solution to the cause of each situation. 1 Current cause This kind of fault is the most common, the circuit breaker selection is too small or the quality is not enough. When designing, we must first calculate the maximum current of the circuit. The rated current of the switch should exceed 1.1 to 1.2 times the maximum current of the circuit. Judgment basis: It does not trip at ordinary times, and only trips when the weather is good and the photovoltaic system has a large power. Solution: replace the circuit breaker with large rated current or circuit breaker with reliable quality. There are two types of miniature circuit breakers, type C and type D, which are trip types. The difference between type C and type D is the difference in short-circuit instantaneous trip current, and the overload protection is the same. The C-type magnetic tripping current is (5-10) In, which means that it trips when the current is 10 times the rated current, and the action time is less than or equal to 0.1 seconds. It is suitable for protecting conventional loads. The D-type magnetic tripping current is (10-20) In, which means that it trips when the current is 20 times the rated current, and the action time is less than or equal to 0.1 seconds. It is suitable for protecting equipment with high inrush current. When there is electrical equipment such as a transformer before and after the switch, and there is an inrush current after power off, D-type circuit breakers should be selected. If the line does not have inductive equipment such as transformers, it is recommended to choose C-type circuit breakers. 2 Voltage cause This kind of fault is relatively rare. There is a rated voltage between the two phases of the circuit breaker, generally the single pole is 250V. If it exceeds this voltage, it may trip. There may be two reasons: one is the wrong selection of the rated voltage of the open circuit; the second is that when the power of the photovoltaic system is greater than the electrical power used by the load, the inverter increases the voltage and sends out electricity. Judgment basis: measure the breaking voltage with a multimeter, which exceeds the rated voltage of the circuit breaker. Solution: Replace the circuit breaker with a higher rated voltage or a cable with a larger wire diameter to reduce the line impedance. 3 Reasons for temperature This kind of fault is also more common. The rated current marked by the circuit breaker is the maximum current that the device can pass for a long time at a temperature of 30 degrees. The current decreases by 5% for every 10 degrees of temperature increase. The circuit breaker is also a source of heat due to the presence of contacts. There are two reasons for the high temperature of the circuit breaker: one is the poor contact between the circuit breaker and the cable, or the contact of the circuit breaker itself is not good, and the internal resistance is large, which causes the temperature of the circuit breaker to rise; the second is the local environment where the circuit breaker is installed Closed heat dissipation is not good. Judgment basis: when the circuit breaker is operating, touch it by hand and feel that the temperature is too high, or see that the terminal has a high temperature, or even a scorched smell. Solution: rewire or replace the circuit breaker. 4 Reasons for leakage The line or other electrical appliances are faulty, other electrical equipment is leaking, the line is leaking, and the insulation of components or DC lines is damaged. Judgment basis: the insulation resistance between the positive and negative poles of the module and the AC phase wire, and between the positive and negative poles of the module, the phase wire and the ground wire is low. Solution: Detect and replace faulty equipment and wires. When tripping due to a leakage fault, you must find out the cause and eliminate the fault before re-closing, and it is strictly forbidden to close it forcibly. When the leakage circuit breaker is tripped, the handle is in the middle position. When it is closed again, the operating handle must be pulled down (breaking position) to make the operating mechanism re-buckle, and then closed. How to choose a leakage protector for the photovoltaic system: Because the photovoltaic module is installed outdoors, the DC voltage is very high when multiple channels are connected in series, and the module will have a small amount of leakage current to the ground. . Generally, the conventional 30mA leakage switch is only suitable for installation in a single-phase 5kW or three-phase 10kW system. If this capacity is exceeded, the protection value of the leakage current should be appropriately increased. If the photovoltaic system is equipped with an isolation transformer, the leakage current can be reduced, but if the isolation transformer wiring is wrong, or there is a leakage problem, it may also trip due to the leakage current. to sum up The switch trip event occurred in the photovoltaic system. If the power station is installed for a long time, the cause may be the wiring problem of the circuit or the switch aging problem. If it is a newly installed power station, there may be problems such as improper switch selection, poor line insulation, and poor transformer insulation. Steel Tendons,Prestressed Tendon Wire,PC Strand Prestressed Tendon,Tendon In Prestressed Concrete Shandong Xindadi Holding Group Co., Ltd , https://www.xindadipcwire.com