接地变压器简称接地变，根据填充介质，接地变可分为油式和干式；根据相数，接地变可分接地变压器为三相接地变和单相接地变。

Grounding transformer or change, according to the filling medium, grounding variable type can be divided into oil and dry; According to the phase number, grounding for earthing transformer is variable can be divided into three phase change and single-phase grounding. 

三相接地变：接地变压器的作用是在系统为△型接线或Y型接线中性点无法引出时，引出中性点用于加接消弧线圈或电阻，此类变压器采用Z型接线，与普通变压器的区别是，每相线圈分成两组分别反向绕在该相磁柱上，这样连接的好处是零序磁通可沿磁柱流通，而普通变压器的零序磁通是沿着漏磁磁路流通，所以Z型接地变压器的零序阻抗很小（10Ω左右），而普通变压器要大得多。按规程规定，用普通变压器带消弧线圈时，其容量不得超过变压器容量的20%。Z型变压器则可带90%～100%容量的消弧线圈，接地变除可带消弧圈外，也可带二次负载，可代替所用变，从而节省投资费用。

Three-phase grounding: the role of the earthing transformer is in type system for delta connection or Y type of neutral point can't elicit elicit neutral point is used to add arc suppression coil or resistance, this transformer USES Z connection, and is the difference between the ordinary transformer and coil of each phase is divided into two groups, respectively, reverse around the magnetic pole, the benefits of such connections are zero sequence magnetic flux can flow along the magnetic column, the zero sequence and ordinary transformer magnetic flux is along the magnetic flux leakage magnetic circuit circulation, so the zero sequence impedance Z earthing transformer is small (about 10 Ω), and ordinary transformer is much larger. According to the provisions of the rules of using ordinary transformer with arc suppression coil, its capacity shall not exceed 20% of the transformer capacity. Z type transformer can take 90% ~ 100% capacity of the arc suppression coil, grounding besides can take away loop, also can bring secondary load, can be used instead of change, so as to save investment costs. 

单相接地变：单相接地变主要用于有中性点的发电机、变压器的中性点接地电阻柜，以降低电阻柜的造价和体积。

Change is mainly used for single-phase grounding: single phase grounding of the neutral point of generator, transformer neutral point grounding resistance cabinets, to reduce the cost of the ark of the resistance and volume. 

1）单相接地电弧发生间歇性的熄灭与重燃，会产生弧光接地过电压，其幅值可达4U（U为正常相电压峰值）或者更高，持续时间长，会对电气设备的绝缘造成极大的危害，在绝缘薄弱处形成击穿；造成重大损失。

1) single phase earthing arcing intermittent out with renewed, can produce arc grounding overvoltage, its amplitude can be up to 4 U (U) as normal phase voltage peak or higher, duration is long, can cause great harm to electrical equipment insulation, the insulation breakdown is weak; In heavy losses. 

2）由于持续电弧造成空气的离解，破坏了周围空气的绝缘，容易发生相间短路。

2) caused by continuous arc air dissociation, damage the insulation of the surrounding air, and prone to short circuit. 

3）产生铁磁谐振过电压，容易烧坏电压互感器并引起避雷器的损坏甚至可能使避雷器爆炸。这些后果将严重威胁电网设备的绝缘，危及电网的安全运行。

3) produce ferroresonance overvoltage, easy to burn out voltage transformer, and cause the damage of the surge arrester and even may make arrestor explosion. The consequences will be serious threat to the insulation of the power grid equipment, endanger the safe operation of power grid. 

为了防止上述事故的发生，为系统提供足够的零序电流和零序电压，使接地保护可靠动作，需人为建立一个中性点，以便在中性点接入接地电阻。接地变压器（简称接地变）就在这样的情况下产生了。接地变就是人为制造了一个中性点接地电阻，它的接地电阻一般很小（一般要求小于5欧）。另外接地变有电磁特性，对正序负序电流呈高阻抗，绕组中只流过很小的励磁电流。由于每个铁心柱上两段绕组绕向相反，同心柱上两绕组流过相等的零序电流呈现低阻抗，零序电流在绕组上的压降很小。即当系统发生接地故障时，在绕组中将流过正序、负序和零序电流，该绕组对正序和负序电流呈现高阻抗，而对零序电流来说，由于在同一相的两绕组反极性串联，其感应电动势大小相等，方向相反，正好相互抵消，因此呈低阻抗。

In order to prevent the accidents, for the system to provide enough of the zero sequence current and zero sequence voltage, make reliable earthing protection action, need people to establish a neutral point, so that the neutral point connected to the grounding resistance. Earthing transformer (ground) is produced in such a situation. Grounding variable is manufactured to a neutral point grounding resistance, the grounding resistance usually is very small (less than 5 o general requirements). Additional grounding transformer are electromagnetic characteristics, the positive sequence, negative sequence current in high impedance in the winding only through a small excitation current. With two on each of the core column winding around the opposite, concentric cylinder on two winding equal zero sequence current flows through the present low impedance, zero sequence current in the winding on the pressure drop is small. When system ground fault occurs, in the heart of the winding through the positive sequence, negative sequence and zero sequence current, the winding of positive sequence and negative sequence current presents high impedance, and for zero sequence current, due to the reverse polarity in the same phase of two winding in series, the induced emf equal, in the opposite direction, just cancel each other out, so a low impedance. 

由于很多接地变只提供中性点接地小电阻，而不需带负载，所以很多接地变就是属于无二次的。接地变在电网正常运行时，接地变相当于空载状态。但是，当电网发生故障时，只在短时间内通过故障电流。中性点经小电阻接地电网发生单相接地故障时，高灵敏度的零序保护判断并短时切除故障线路，接地变只在接地故障至故障线路零序保护动作切除故障线路这段时间内起作用，中性点接地电阻和接地变才会通过零序电流。

Because only provide many earth changes small neutral grounding resistance, without load, so a lot of ground is to belong to no secondary. Grounding during normal operation of power grids, variable is equal to the idle state. But, when a fault happens in, only through the fault current in a short time. Neutral point via small resistance grounding grid of single-phase grounding fault occurs, high sensitivity of zero sequence protection and short resection fault lines, grounding is only between ground fault and fault line zero sequence protection action to remove the fault line work this period of time, neutral point grounding resistance and the change will only be through the zero sequence current. 

接地变是人为的制造一个中性点，用来连接接地电阻。当系统发生接地故障时，对正序负序电流呈高阻抗，对零序电流呈低阻抗性使接地保护可靠动作。

Made a neutral point grounding variable is artificial, used to connect the grounding resistance. When the system ground fault occurs, the positive sequence, negative sequence current in high impedance of zero sequence current is low impedance grounding protection and reliable action.