Brief Analysis of Coil Insulation Structure

For motor products, the winding is the heart of the motor, and the winding itself should be insulated from the iron core and other parts. If it is a three-phase motor, the phases of the winding should also be insulated.

Coil insulation structure
The insulating structure is a structure formed by combining the same or several insulating materials through a specific process, which is called an insulating structure. It mainly involves turn-to-turn insulation, ground-to-ground insulation, and outsourcing insulation. If it is a three-phase motor, it will also involve phase-to-phase insulation.

Turn-to-turn insulation
Turn-to-turn insulation refers to the insulation between turns of the same coil, and its function is to separate conductors with different potentials in the motor windings from each other to avoid short-circuit between turns. For enameled wire winding, the inter-turn insulation is the insulating varnish on the surface of the electromagnetic wire, while for wire-covered wire and mica wire, it is a composite insulating material bonded by specific insulating materials and insulating glue.

In general, the turn-to-turn insulation only depends on the insulation of the magnet wire itself, such as enameled wire, single glass wire or double glass wire. Glass fiber enameled wire, polyimide film sintered wire, etc. have their own insulation. Turn-to-turn insulation is the most important and usually relatively weak insulation in the insulation structure of the motor. Therefore, attention should be paid to the selection of materials when designing the turn-to-turn insulation. During the manufacturing process, attention must be paid to the fact that the wire should be smooth and free from flashes, burrs, etc. The inter-turn insulation cannot be damaged by mechanical strain.

Insulation to ground
Insulation to ground refers to the main insulation on the outside of the coil. It mainly bears the rated voltage of the motor or the possible overvoltage. Its working voltage is relatively high, so its electrical, mechanical and thermal properties must meet the requirements of the motor's operating state. The thickness of the insulation to the ground generally depends on the rated working voltage of the motor and the electrical and mechanical properties of the insulating material. The higher the rated voltage of the motor, the more layers of insulation wrapping to the ground, or the thicker the paint film.

Outsourcing insulation
Outer insulation refers to the insulation wrapped around the coil to the main insulation. And its main function is to protect the main insulation from mechanical strain and make the whole coil firm and neat, which plays a reinforcing role in the main insulation. Most of the outer insulation is made of glass ribbon. You can see the enameled square aluminum wire.

Insulation between phases
Phase-to-phase insulation is the unique insulation of three-phase motors, and it is the insulation between phases. For scattered windings, interphase blocks are used to separate the two phases, and insulating hoses are also used at the ends of the windings; the interphase insulation of hard windings is realized by plate-shaped insulating materials or relative distance spaces.

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