Auto recloser comparison of technical routes

The auto recloser is an important piece of equipment in the distribution network. According to the breaking capacity, it can be divided into auto circuit recloser and load switches breakers. The load switch breaker has a cost advantage in the early stage. However, with technological progress in recent years, production efficiency has improved. The cost advantage is not big, so the usage is getting less and less, so today we mainly look at the auto circuit recloser.

There are many types of pole-mounted auto circuit reclosers in use in the market. Let’s compare these breakers and take a detailed look at the characteristics of each type of breaker.

At present, the pole-mounted auto circuit reclosers on the market are divided into column type and common box type according to their structural forms, and they are divided into air insulation and SF6 insulation according to their insulation methods (oil insulation is basically useless), according to the arc extinguishing method. Divided into vacuum arc extinguishing and SF6 arc extinguishing.

The above-mentioned different structures, insulation, and arc extinguishing forms are combined to produce these types of switches: In addition, there are several new types of pole-mounted circuit breakers on the market. Let’s take a look at them below.

LW3 (LW56) Load Breakers Switch

Advantages:

  1. SF6 insulation is adopted, SF6 arc extinguishing, because it is SF6 arc extinguishing, the opening distance of the switch is relatively large,
  2. The fracture distance is greater than 35mm, and the fracture can be used as an isolation switch to using with obvious breaking points.

Disadvantages:

  1. A switch that needs to be charged with positive pressure SF6 gas, the charging pressure is about 3-4 atmospheres, and the positive pressure will increase the probability of air leakage, and the temperature change will make the air box bear more pressure, so the process requirements for the air box very high.
  2. The amount of SF6 used in the switch is relatively large, which is not good for environmental protection and needs to be properly disposed of at the end of its life.
  3. The breaking capacity is weak, it is difficult to reach the current mainstream 20kA, and the electrical life is also limited.
  4. External electromagnetic PT is used to take power, an electromagnetic transformer is used for measurement and protection, and there is a risk of ferromagnetic resonance.

ZW20 Load Breakers Switch

Advantages:

  1. SF6 insulation is adopted, but the inflation pressure is zero pressure, the risk of air leakage is reduced, and the air box is required.
  2. Arc extinguishing vacuum arc extinguishing, strong breaking capacity.

Disadvantages:

  1. There is still SF6 gas, although the amount of inflation is small, a large number of applications will still have a bad impact on the environment.
  2. The external electromagnetic PT is used to take power, and the electromagnetic transformer is used for measurement and protection, and there is a risk of ferromagnetic resonance.

ZW32 Recloser

Advantages: Zero SF6 gas usage, environmentally friendly. Vacuum arc extinguishing, strong fault-breaking capacity, and high electrical life. The overall structure of the switch is simple and the stability is good.

Disadvantages: External electromagnetic PT takes power, and an electromagnetic transformer is used for measurement protection, which has the risk of ferromagnetic resonance.

ZW68 Breakers Switch

The ZW68 switch is a new type of on-column switch developed by the Electric Power Research Institute, and a certain fee is required to obtain production technology.

Advantages:

  1. Built-in direct-acting isolating switch, which is the only one at present.
  2. Dry air + solid insulation, environmentally friendly and pollution-free.

Disadvantages:

  1. The volume and weight are large, about 1.5 times that of the existing switch, and the difficulty of on-site installation is higher.
  2. Using the cast aluminum shells, the cost rises significantly.
  3. The operating mechanism is too complicated, and the more complicated things are, the higher the probability of failure.

ZW32 Auto Circuit Recloser

The ZW32 auto circuit recloser completely inherits the advantages of the traditional ZW32 recloser, including simple and reliable structure, no SF6 gas, environmentally friendly, high mechanical life, and electrical life. At the same time, all the traditional electromagnetic transformers are replaced by electronic transformers to eliminate the influence of magnetic saturation. a new type of capacitor power-taking device is used in the power extraction, which avoids the risk of PT explosion caused by ferromagnetic resonance. With the continuous progress of electronic sensors and capacitive power acquisition technology in recent years, this kind of switch will be the first choice product worthy of widespread use in the future.

Summary: The technical development of the auto circuit recloser should be based on the actual needs of users. The technology that is simple, reliable, economical, and practical, and can solve the actual problems of users is a good technology.

Strong Power Electric ZW32 auto circuit recloser was designed on the basis of ZW32 recloser. The integrated solid-sealed pole column integrates a variety of advanced power equipment construction technologies, micro-power electronic sensing technology, wireless communication technology, and online power extraction. Technology, etc.; 11 electronic sensors (4 currents, 7 voltages) are integrated, with three-phase current, power supply voltage, load-side voltage, zero-sequence voltage and zero-sequence current, of which the current reaches 0.5s and the voltage reaches 0.5 level; the partial discharge of the whole machine is less than 10pC. The bottom and side double signs make the operation more user-friendly. The switch body can have its own 20W power supply, lithium battery + super capacitor dual backup power supply, and the FTU(recloser controller) has a single-phase grounding algorithm, which adopts a steady-state criterion and a variety of transient criteria for comprehensive judgment; the product has been tested by RTDS simulation system and the China Electric Power Research Institute The true type detection, the true type detection has passed the high-resistance 4K fault grounding and arc grounding detection. At present, the high resistance fault judgment ability of Strong Power Electric has reached 6K.

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