Current cause

This kind of failure is most common, the circuit breaker is too small, or the circuit is aging. When designing, 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. It is recommended to replace the switch every 5 to 8 years.

Voltage cause

There is a rated voltage between the two phases of the circuit breaker. Generally, the single pole is 250V. If the DC voltage is 1000V, it needs 4 series connections to meet this voltage. The AC inverter now has output voltages of 400V, 480V, 500V, 540V, 800V, etc. A variety of specifications, pay attention to the selection when designing. There may be two reasons for the overvoltage trip: one is the wrong selection of the rated voltage of the circuit breaker; the other is that when the power of the photovoltaic system is greater than the power consumption of the load, the inverter increases the voltage and sends electricity to the outside.

temperature reasons

This kind of fault is also common. The rated current marked on the circuit breaker is the maximum current that the device can pass for a long time at a temperature of 30 degrees, and the current decreases by 5% for every 10 degrees of temperature increase. The circuit breaker is also a heat source because of the existence 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 in good contact, 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.

Cause of leakage

The insulation layer of components or DC lines is damaged, the switch selection is too small, and the lines or other electrical appliances are faulty. When the trip is caused by leakage fault, the cause must be found out and the fault is eliminated before reclosing. Forcible closing is strictly prohibited. When the leakage circuit breaker breaks and trips, the handle is in the middle position. When it is re-closed, the operating handle needs to be pulled down (breaking position) first, so that the operating mechanism is re-closed, and then closed upwards.

How to choose leakage protector for photovoltaic system

Since photovoltaic modules are installed outdoors, the DC voltage is very high when multiple channels are connected in series, and there will be a small amount of leakage current between the modules and the ground. Therefore, when selecting a leakage switch, the protection value of leakage current should be adjusted according to the size of the system. Generally, a 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.