High-power DC stabilized power supply protection type
Overcurrent protection mainly includes two types of short circuit protection and overload protection.
Overload current:
The electrical circuit is overloaded due to too many connected electrical equipment or overloaded power supply equipment (for example, the mechanical load of the connected motor is too large). Its current value is not much more than the current carrying capacity of the circuit, and the consequence is that the working temperature exceeds the allowable value, which will accelerate the deterioration of the insulation and shorten the life span, and it does not directly cause disasters. The characteristics of overload protection are small set current and inverse time limit action. Thermal relays and time-delayed electromagnetic current relays are often used as overload protection components. Fuses are also commonly used as overload protection components without too much inrush current. In the TN system, when using fuses for short-circuit protection, the rated current of the melt should be less than 1/4 of the single-phase short-circuit current; when using circuit breakers for protection, the setting of the overcurrent release for instantaneous action or short delay action of the circuit breaker The current should be less than 2/3 of the single-phase short-circuit current.
Short circuit current:
The short-circuit protection of high-power DC stabilized power supply is characterized by large set current and instantaneous action. Electromagnetic current releases (or relays) and fuses are often used as short-circuit protection components. When the loop insulation is damaged for various reasons (including overload), conductors with unequal potentials conduct through the fault point with negligible impedance, which is called a short circuit. Since the paths of this short circuit are all metal paths, this short circuit is classified as a metallic short circuit, and its short circuit current value can reach hundreds or even thousands of times the current carrying capacity of the loop conductor, which can generate abnormally high temperature or huge mechanical stress. resulting in various disasters.
