Why should the transformer be specially protected by a self-recovery fuse?

The damage of the transformer is mainly due to low-level overvoltage, secondary short-circuit, and overcurrent. This will cause the transformer's "copper loss" (heat loss when current flows through the coil) and "iron loss" (loss caused by "eddy current") to increase dramatically in a short period of time, and cause the temperature of the coil to rise; The cause of over-current is usually a short circuit or reverse polarity; this way the loop current becomes larger.
The coil of the transformer is usually thinner. When the large electricity flows smoothly, the coil will have a fever and the temperature will rise. Above a certain temperature (under normal circumstances, the upper layer oil of the transformer does not exceed 85°C, and the maximum does not exceed 95°C), the insulating paint outside the coil melts. This is easy to short-circuit, and even cause the circuit to smoke or catch fire, so as to damage the components in the circuit, and it will also be overloaded. In severe cases, the transformer will fail due to overheating, and the local circuit will be damaged.

How to protect the transformer?

People usually connect thermal fuse (thermal fuse) in series in low-level circuit or connect electric fuse (current fuse) in series in secondary circuit to protect transformer. The biggest disadvantage of this scheme is that it uses disposable protective components. If the fuse is blown, the transformer will be scrapped, which greatly increases the maintenance cost of the equipment. Recoverable circuit breaker is another overcurrent protection method in the circuit, but its cost is too high, so it is not suitable for use in all circuits. Some use bimetallic segment circuit protector, its limitation is that it repeatedly turns on and off when the fault is not eliminated; And its protection is that it has been working for a period of time (about 50 seconds) at a limited temperature, and it has already damaged the insulated coil of the transformer, which is very dangerous. For this reason, we recommend using self-recovery fuses as transformer protection components to avoid the shortcomings of the above protection methods.

The failure of power supply equipment with transformers is mainly caused by overcurrent. The cause of overcurrent is usually a short circuit or reduced load;
When a fault occurs, it will cause the circuit to smoke or catch fire, so as to damage the circuit and the interface.

The transformer of the lamp body of the low-voltage halogen lamp structure often fails due to a short circuit.
If the installation and connection between the transformer and the lamp body are improper, it is more prone to damage.
Since the lamps are used in parallel, the current is particularly large when short-circuited.
Install the resettable fuse on the second coil of the transformer to prevent short circuit and overload faults.