Preface: In our daily life and production process, unbalanced three-phase load often occurs. The problem of electricity consumption has always been the country’s attention, so we need to understand the principle of the occurrence of three-phase imbalance. Understand the hazards and solutions of three-phase unbalance.
The principle of three-phase unbalance is that the amplitudes of three-phase current or voltage in the power system are inconsistent. The amplitude difference exceeds the specified range. The uneven load distribution of each phase, the non-simultaneity of unidirectional load power consumption and the access of single-phase high-power load are the main reasons for the three-phase imbalance. It also includes the inadequacy of power grid construction, transformation and operation and maintenance, which is an objective reason. To give the simplest example, in daily life, most household appliances and lighting equipment are single-phase loads. Due to the large number and different activation times, the voltage of some users will be low, resulting in the failure of some electrical appliances to work normally. The high voltage of some users will cause more serious harm to the aging of circuits and insulators. These can be summed up as the harm caused by the three-phase imbalance.
The harm caused by the three-phase imbalance is the first to bear the brunt of the harm to the transformer. Due to the unbalanced three-phase load, the transformer operates in an asymmetric state, resulting in an increase in the loss of electric energy, which includes no-load loss and load loss. The transformer runs under the unbalanced state of the three-phase load, which will cause excessive current. The temperature of local metal parts increases, and even leads to the damage of the transformer. In particular, the copper loss of the transformer is increased, which not only reduces the output quality of electric energy, but also easily causes inaccurate measurement of electric energy.
In addition to the harm to the transformer, it has an impact on other electrical equipment, because the imbalance of the three-phase voltage will lead to the imbalance of the current, which will increase the temperature of the motor, increase the energy consumption, and generate vibration. The service life of electrical equipment is greatly reduced, and the maintenance and repair costs of daily equipment are increased. Especially in the event of overload and short circuit, it is easier to cause other losses (such as fire). At the same time, as the voltage and current imbalances increase, this also increases the line loss of the circuit.
Faced with the three-phase imbalance that has created many harms for us, how should we come up with solutions? The first should be the construction of the power grid. At the beginning of power grid construction, it should cooperate with relevant government departments to carry out reasonable power grid planning. Strive to solve the problem of three-phase imbalance at the source of the problem development. For example, the construction of the power distribution network should follow the principle of “small capacity, multiple distribution points, and short radius” for the location selection of distribution transformers. Do a good job of low-voltage meter installation, so that the distribution of the three phases is as uniform as possible, and avoid the phenomenon of load phase deviation.
At the same time, because the three-phase imbalance will cause current to appear in the neutral line. Therefore, multi-point grounding of the neutral line should be adopted to reduce the power loss of the neutral line. And the resistance value of the neutral line should not be too large, and the resistance value is too large, which will easily increase the line loss.
When we understand the principle of three-phase imbalance, its harm and how to deal with it, we should strive to make the three-phase balance. When the current passes through the line wire in the power supply network, because the line wire itself has a resistance value, it will cause power loss for power supply. Therefore, when the three-phase current develops in balance, the power loss value of the power supply system is the lowest.
The three-phase unbalance control device produced by Hongyan Electric can effectively control the problems of three-phase unbalance, low terminal voltage, and bidirectional compensation of reactive current in the transformation and upgrading of distribution network.
Post time: Apr-14-2023