The stator core is formed by laminating thin silicon steel sheets coated with insulating paint on the surface. Since the silicon steel sheets are thin and insulated between the sheets, the core eddy current loss due to the passage of alternating magnetic flux is reduced. Today, the editor of Dalan Motor specifically introduces the insulation effect of each silicon steel sheet of hydraulic oil pump motor.
1. The silicon steel sheet itself is also an electrical conductor. Under the action of AC magnetic flux, an induced current is also generated in the core. This cannot be avoided.
2. If the iron core is a whole, it is equivalent to a conductor with a large area, the circuit is short, and its resistance value is very small. Although the induced voltage is not high, the current is very large. This produces great eddy current (circulation) losses. In severe cases, the iron core will be locally melted, commonly known as the iron core "fire".
3. After the insulating paint is applied between each piece, the section where the iron core is produced is divided into many small section conductors. In this way, its resistance becomes larger. Therefore, although the painted iron core also has eddy current loss (part of the iron loss), it is also much smaller.
4. Therefore, the thinner the silicon steel sheet, the smaller the loss. Normally, the insulating paint on the surface of cold-rolled silicon steel sheet has been painted before leaving the factory. As long as we don't damage him, we don't need to paint again.
There are two types of insulating coatings currently in use:
One is phosphoric acid monochromic acid coating, the coating liquid is dark orange transparent liquid, the use temperature is 70 ～ 80 ℃, the interlayer resistance is 5 ～ 50Ω • cm2 / sheet; the other is resin and chromic acid Coating, the coating liquid is milky yellow mucus, the use temperature is less than 30 ℃, the interlayer resistance is the same as the previous one
The requirements for paint film thickness and insulation resistance are:
(1) Apply paint once: 8000kVA and below, voltage 35kV and below, double-sided paint wax thickness 0.01-0.015mm, insulation resistance 10Ωcm2 / piece.
(2) Apply the paint twice: 8000 to 31500kVA, 110kV and below, the thickness of the double-sided paint film is 0.015 to 0.02mm, and the insulation resistance is 15Ωcm2 / piece.
(3) Apply paint three times: more than 31500kVA, voltage higher than 110kV, double-sided paint film thickness of 0.02-0.025mm, insulation resistance of 20Ωcm2 / piece.
(Whether the insulation resistance of the silicon steel sheet paint film is as large as possible
?
answer:
no.
Because the iron core should be a path to the ground
(
use
500V
Shake the meter to measure the widest part of the upper iron yoke and the upper clip with the grounding lug
Pieces should be access
)
. If the insulation resistance of the lacquer wax is too high, it may cause the core to not be completely grounded.
)
Is the insulation resistance of the silicon steel film of the motor greater?
Answer: No. Because the iron core should be a path to the ground (use a 500V shake meter to measure the widest part of the upper iron yoke and the upper clip with the grounding piece should be a path). If the insulation resistance of the lacquer wax is too high, it may cause the core to not be completely grounded.
----- Responsible Editor: Dalan Oil Pump Motor 02-Procurement Consultant
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