Usually, the arc suppression coil supports the earthing transformer. It realize the fault protection when the grid single phase grounding through the computer control and load tap. Its aims are to blowout the arc and avoid the system power cut for the tripping operatiom.
The 66kv and below power supply system of China mainly applies neutrality point insulation way to supply power that is not earthing operation mode. And therefore in order to complete grounding protection it need to equip the earthing transformer to supply the neutrality point.
Arc suppression coil is the adjustable inductor connection between grid neutrality point and the ground. Its function is to compensate the capcitance current of the single phase grounding of the power supply system when single phase grounding faults happen, and thus to reduce the grouding fault current and eliminate the arc grounding role.
There are two types of mode of the arc suppression coil supply the emotional current: one is adjust turn and capatity and the other is second side regulate capacity.
There are several taps on the arc suppression coil of the adjustable turn arc suppression coil, and it applies the load tap to regulate the turn of arc suppression coil to change the inductance value. When the grid normally operated, computer controller calculates the capacitance current of the grid through real time measurement of amplitude of the arc suppression coil current and phase changes, and it adjust the on-load voltage regultion tap by the controller according to teh presetted minimum residual value or the mistune. And thus make it on the needed compensation block, the residual flow of the fault site can be limited on the arranged scope. It applies the over compensation way, arc suppression coil in the grounding circuit sereis the damping resistance when normally operated.
The differenct current regulation and different tap of the arc suppresion coil products can be developed according to the actual situation. The max current adjustmant range can up to 4:1, and the largest tap can up to 25 class. And there are two distribution ways of the each class current gradient, one is arithmetic distribution and the other is geometric distribution. The user can make choice according to the design.
Adjustable capacity arc suppression coil adds second side capacitance load windings on the base of arc suppression coil. In the second side as the load shunt with several groups of controlled sillicon (vacuum switch) tap capacitor to regulate the capacitance resistance value of the second side capacity. According to the impedance conversion principle, to regulate secondary side capacitance resistance value can chage the inductive current of the first side. There are a variety of combination way of the capacitance value and the number of groups to meet the requirements of regulation scope and accurancy.
The adjustable range of the general adjustable capacity arc suppression coil current is large: up to 10:1, and the output voltage of the secondary side classified as 400V, 600V, 800V. The system is 4％－10％ of its short circuit impedance voltage 10 KV, and 6％－15％ of the 35KV system. CNEKE transformers can be designed according to the service conditions and the user can also make choice.
The function of are suppression coil is to outlet the arc, cross connect between the neutrality poit and grounding, and therefore its the single phase structure. The function of the earthing transformer is provide a earthing neutrality point for the △ vector group grid, and at the same time the earthing transformer increase the secondary winding (400V), and can be used as a substation distribution transformer. The general vector group of earthing transformer is Zn,yn11, the earthing transformers without secondary side is provide the zero sequency impedance of the single phase grounding of the three phase grid.
The supporting parameter of the earthing transformers and arc suppression coil are the match of the grounding current, that is, the rated 2h grounding current (the toatal of zero sequency three phase) of earthing transformer equals to rated 2h grounding current (the max working current of arc suppression coil) arc suppression coil.
The resin casting formed dry earthing transformers and arc suppression coil of CNEKE transformers are both core reactors products, F-class high temperature insulation structure.