What is the role of high resistance and low resistance of high voltage motor coils?
The manufacture of coils for high-voltage motors is a very cumbersome task, such as winding, forming, gelling, wrap-mastering, high-resistance and low-resistance. Today I mainly talk about the role of high resistance and low resistance band.
The insulation of the high-voltage motor windings is all on the coil. The iron core adopts an open slot. After the coil is placed in the slot, the slot wedge is finally covered. According to the specific requirements of the motor, most of the high-voltage motors adopt magnetic slot wedges.
Today we will talk about a question, why should the outer part of the coil be coated with high resistance and low resistance band? On the straight side of the motor coil, after the process is required to package several layers of mica tape, then half a stack of low resistance tape, on the straight side The high-resistance stack is used at the transition junction of the end. The purpose is to prevent corona damage to the winding, because the position of the core slot and the end of the winding are stronger than the position of the straight side, so high-resistance bands are used in these parts.
In the process of weaving, it is necessary to prevent the damage of high and low resistance materials. In many motor manufacturers, the low resistance band on the straight side is damaged during the weaving process, or the notch is scratched. Bigger damage.
About high resistance and low resistance materials
The insulating tape on the high-voltage coil of the motor is divided into a high-resistance belt and a low-resistance belt, and the high-resistance belt is made of an alkali-free glass fiber ribbon immersed in a semiconductor high-resistance paint for the end portion of the wire rod. The low resistance zone mainly consists of an alkali-free glass fiber tape containing an asbestos tape and a semiconductor low-resistance paint. The iron asbestos belt is woven from asbestos fiber yarn; the low resistance belt is used for the wire rod groove portion.
(1) Low resistance materials. There are mainly acetylene black, which is carbon which is precipitated when gaseous, liquid or solid organic matter is not completely burned, and is used as a conductive base for anti-corona paint. There is also graphite, which is a crystal of carbon.
(2) High resistance materials. Mainly silicon carbide, used to formulate high resistance nonlinear paint. Silicon carbide has a non-linear resistance characteristic, and its resistivity decreases with the applied field strength, that is, it has the ability to adjust the field strength, so that the surface potential of the outer rod end of the notch is evenly distributed. For the silicon carbide coating used at the end, the medium resistance is made of 320-400 mesh silicon carbide, and the high resistance is made of 1600-1800 mesh silicon carbide.
