The influence of three-phase load imbalance? 1. Low voltage network loss increases. According to the root mean square current method, the power loss: Δ P = 3I2R 10-3, the three-phase load imbalance is larger than the balanced load loss. 2. The imbalance of three-phase load affects the output of operating equipment. The capacity design of power supply equipment is determined by the condition of three-phase load balancing. if the three-phase load is unbalanced, the equipment capacity can only be limited to the maximum one phase of the three-phase load, so the output of the equipment is reduced. For example, the secondary rated current of 100kVA distribution transformer is 144A. If IA=144A, IB and IC are 72A respectively, the output of distribution transformer is only 67%. 3. The three-phase load is unbalanced, the neutral line current increases, and the three-phase voltage is unbalanced. The three-phase load is unbalanced and the neutral line has zero-sequence current through the generation of zero-sequence flux in the core, but it is not offset by the flux from the primary side and overlaps on the main flux of the original positive phase sequence. This zero-sequence flux will induce zero-sequence potential in the primary and secondary side coils and add it to the terminal voltage of each phase, resulting in three-phase voltage asymmetry and displacement of the neutral point. When the load of the phase in the three phase is large, the phase voltage decreases, while the phase voltage of the phase with small load increases (when the welder is used in normal operation, the voltage of one phase of the welder decreases, and the light bulb on the other two phases is damaged.). For this reason, it is stipulated that the neutral current shall not exceed 25% of the secondary rated current of the distribution transformer. If the control neutral current does not exceed 25%, the neutral point displacement will not seriously affect the three-phase voltage asymmetry. 4. If the neutral current is too large, the operating temperature of the distribution transformer will rise, and if it is serious, the distribution transformer will be damaged. When the neutral current is too large, the zero sequence flux produced by the zero sequence current will pass through the oil tank wall and steel structure, resulting in a large power loss, thus increasing the operating temperature of the distribution transformer. 5. The imbalance of three-phase load results in the imbalance of three-phase voltage, which affects the output power of the motor and increases the temperature of the winding. When the three-phase voltage is unbalanced, a reverse rotating magnetic field is generated in the stator of the induction motor, and the induction motor runs under the action of positive and inverse magnetic fields. Because the positive sequence rotating magnetic field is larger than the reverse rotating magnetic field, the rotation direction of the discharge motor is still the same as the positive sequence direction, but the existence of the rotor reverse sequence magnetic field produces a larger reverse sequence braking torque, which reduces the output power of the motor and increases the winding temperature. thus endangering the safe operation of the motor. 6. The imbalance of three-phase load affects the accuracy of watt-hour meter and increases the error of watt-hour meter. In the active watt-hour meter 1 from the error curve of the three-phase two-element watt-hour meter, when the position of curve 2 (the error curve of one-phase current at 00:00) is translated, the position (degree) of the translation depends on the change of the three-phase load.