Causes and Countermeasures of Abnormal Tripping of Stabilized Power Supply
When people use some regulated power supplies, they often encounter this phenomenon. When the power is turned on, the overcurrent protection device trips suddenly, and the current in use is lower than the rated current of the overcurrent protection device; sometimes it trips frequently during use. In the design of a regulated power supply, there are generally two protections for current and voltage. There are several reasons for tripping: some are because the capacity of the transformer in the regulated power supply is not enough, some manufacturers cut corners in order to reduce costs, and the quality of the workmanship cannot pass the test. If the input voltage is low, the current of the transformer will be too large. As a result, it is easy to generate heat and cause the coil to burn out, so the protection current value is deliberately lowered, causing the overcurrent protection device to trip frequently; the other is the problem of the quality of the components of the protection device itself; if these problems do not exist, it is stable. The electronic control circuit of the piezoelectric power supply is not equipped with a soft-start device in the design, which causes the instantaneous surge current of the regulated power supply to cause tripping when it is turned on. Another reason is that the input voltage of the power grid is too low or too high, which has exceeded the scope of use of the regulated power supply. The low-voltage or high-voltage protection device of the regulated power supply is activated to protect household appliances, which is normal work. to solve
We can consider these issues from the following aspects:
1. The load matches the regulated power supply
The load has a direct relationship with the capacity and input voltage of the regulated power supply. In the case of a certain load, if the voltage of the power grid is low, then the regulated power supply should be selected
Choose a model with a larger capacity and a wider input range. For household appliances with inductive loads, such as air conditioners and refrigerators, which have certain requirements on the input voltage, the output voltage precision should be selected.
The temperature is 200V ± 10% and there is a regulated power supply with voltage and time delay protection devices to avoid damage to household appliances.
2. Selection of components
The quality of a component will affect the normal operation of the regulated power supply, so manufacturers must strictly control when purchasing components to avoid malfunctions of the regulated power supply.
3. Rational design of the circuit
Since some regulated power supplies do not have a soft-start device in the design, the reactance is small, and the instantaneous surge current can reach several times or even dozens of times the normal operating current.
In order to solve this problem, the inductance of the transformer can be increased, but the cost increase is too large.
After referring to the relevant data and many tests, we think that in addition to rationally adjusting the time constants of the reference voltage, sampling voltage and comparison voltage to reduce malfunctions, a soft start circuit can be selected according to the situation. This kind of circuit mainly adds a soft-start relay to the original circuit. When the regulated power supply is in the instant state of starting up, the soft-start relay does not act. At this time, the circuit reactance is the largest, reducing the surge current, and then the soft-start relay acts. The power supply regulator is in working condition, thus solving the tripping phenomenon caused by the instantaneous surge current generated by starting up.
