The tripping of the leakage protector is a common thing in photovoltaic systems, but the reason is more difficult to find. So what are the reasons for the leakage protector to trip on rainy days?
The leakage protector, referred to as the leakage switch, is also called the leakage circuit breaker. It is mainly used to protect the equipment from electric shock and electric shock to persons with fatal danger. It has overload and short-circuit protection functions, and can be used to protect the circuit or motor. Short circuit can also be used for infrequent switching of the line under normal circumstances. When it rains and the air is humid, it is easy to leak electricity, and the leakage protector works, indicating that the components in the system, cables or live parts of the inverter have insulation damage.
Several reasons for the tripping of the leakage protector
1. The insulation resistance of the DC part is too low
Insulation resistance is to detect the DC part of the photovoltaic system, including components and DC cables. When the inverter detects that the insulation resistance of the positive or negative poles of the component side to ground is too low, it means that the DC side cables or components have abnormal ground insulation resistance. Low insulation resistance is a common fault in photovoltaic systems. Damage to components, DC cables, and connectors, and aging of the insulation layer will result in low insulation resistance. When the DC cable passes through the bridge, there may be barbs on the edge of the metal bridge. During the threading process, It is possible to damage the outer insulation of the cable, resulting in leakage to the ground.
2. AC leakage current
The leakage current is also called the residual current of the square matrix. Smaller, the common-mode voltage will form a large common-mode current on the parasitic capacitance between the photovoltaic system and the ground, that is, leakage current.
The threshold value of DC insulation fault alarm is 30mA, and the threshold value of leakage current fault is 300mA, so when the insulation layer of the DC part is damaged, the insulation resistance will be reported first, and the inverter will be shut down, unless the DC cable is damaged, generally not. A leakage current fault will be reported. When a leakage current fault occurs in the inverter, generally check the inverter and the AC part.
3. The leakage protector is poorly installed
If the leakage protector is not firmly connected to each terminal during installation, it will often cause the terminal to heat up and oxidize over time, causing the wire insulation to be scorched, accompanied by the smell of ignition and burning rubber and plastic, causing the wiring Undervoltage trips the leakage protector.
4. The quality of the leakage protector itself
When purchasing leakage protectors, users should try their best to buy them from reputable designated manufacturers or stores.
5. The leakage protector does not match the photovoltaic capacity
The output current of the photovoltaic system exceeds the rated current of the leakage protector, causing the leakage protector to trip.
6. The grid voltage is too high
Due to the three-phase imbalance or the disturbance of small animals such as mice, the voltage drift occurs in the main zero line of the power supply, and the phase voltage can be changed from 220V to 380V, which will trip the leakage protector.
If the leakage protector trips, the inspection should follow the principle of first simplicity and then complexity. First, check whether the installation is good, and then check whether the power supply incoming line voltage is too high (see the neighbors) and whether there is any problem with the leakage protector itself (remove it). Drop the line to send power), and then check whether the capacity of the leakage protector is sufficient, and finally check whether the load, line leakage or short circuit. Professionals should be asked to use professional equipment to check. For example, use a multimeter to measure the voltage of the component to ground, and an insulation resistance meter to measure the insulation resistance of the component side to ground and the AC output line to ground one by one. The impedance needs to be larger than the inverter insulation resistance of the valve. value requirement.