METHOD FOR CONTROL OF IMPREGNATED INSULATION HARDENING FOR WINDINGS OF ELECTRIC PRODUCTS Russian patent published in 2014 - IPC H02K15/12 

FIELD: electricity.

SUBSTANCE: batch of samples is prepared preliminary for an impregnating compound with different degree of dryness for each sample and dependency of the dielectric permittivity on frequency of the electromagnetic field is defined for the above samples. According to the defined dependencies two measurement frequencies are selected, one frequency f₁ lies in a dispersion region of the non-hardened insulating impregnating compound while the other frequency f₂ lies in an optical region of the non-hardened insulating impregnating compound. Using the defined frequency dependencies for the samples dryness and the dielectric permeability curves for the impregnating compound are plotted as $$\frac{\lg {\epsilon }_{ic}\left(f_2\right)}{\lg {\epsilon }_{ic}\left(f_1\right)},$$ where ε_ic(f₁) ε_ic(f₂) are values of the dielectric permeability for the impregnating compound measured at frequencies f₁ and f₂ of the electromagnetic field respectively. Thereafter for each controlled winding capacitance-to-case values C_bi(f₁) and C_bi(f₂) for two selected frequencies before impregnation and capacitance values after impregnation and drying C_ai(f₁) and C_ai(f₂) are measured, and according to the measurement results the following ratio is calculated $$\frac{{\text{lgε}}_{\text{ic}}\left({\text{f}}_{\text{2}}\right)}{{\text{lgε}}_{\text{ic}}\left({\text{f}}_{\text{1}}\right)}=\frac{{\text{lnC}}_{\text{ai}}{\text{(f}}_{\text{2}}\text{)}+{\text{ln[C}}_{\text{eq}}\left({\text{f}}_{\text{2}}\right)-{\text{C}}_{\text{bi}}\left({\text{f}}_{\text{2}}\right)\text{]}-{\text{lnC}}_{\text{bi}}\left({\text{f}}_{\text{2}}\right)-{\text{ln[C}}_{\text{eq}}\left({\text{f}}_{\text{2}}\right)-{\text{C}}_{\text{ai}}\left({\text{f}}_{\text{2}}\right)\text{]}}{{\text{lnC}}_{\text{ai}}{\text{(f}}_{\text{1}}\text{)}+{\text{ln[C}}_{\text{eq}}\left({\text{f}}_{\text{1}}\right)-{\text{C}}_{\text{bi}}\left({\text{f}}_{\text{1}}\right)\text{]}-{\text{lnC}}_{\text{bi}}\left({\text{f}}_{\text{1}}\right)-{\text{ln[C}}_{\text{eq}}\left({\text{f}}_{\text{1}}\right)-{\text{C}}_{\text{ai}}\left({\text{f}}_{\text{1}}\right)\text{]}},$$ where $${\text{C}}_{\text{eq}}\left({\text{f}}_{\text{1}}\right)=\frac{{\text{2pSε}}_{\text{0}}{\text{ε}}_{\text{e}}\left({\text{f}}_{\text{1}}\right){\text{ε}}_{\text{f}}\left({\text{f}}_{\text{1}}\right)}{{\text{3[d}}_{\text{e}}{\text{ε}}_{\text{f}}\left({\text{f}}_{\text{1}}\right)+{\text{d}}_{\text{f}}{\text{ε}}_{\text{e}}\left({\text{f}}_{\text{1}}\right)},$$ $${\text{C}}_{\text{eq}}\left({\text{f}}_{\text{2}}\right)=\frac{{\text{2pSε}}_{\text{0}}{\text{ε}}_{\text{e}}\left({\text{f}}_{\text{2}}\right){\text{ε}}_{\text{f}}\left({\text{f}}_{\text{2}}\right)}{{\text{3[d}}_{\text{e}}{\text{ε}}_{\text{f}}\left({\text{f}}_{\text{2}}\right)+{\text{d}}_{\text{f}}{\text{ε}}_{\text{e}}\left({\text{f}}_{\text{2}}\right)}$$ are equivalent capacitance values for the in-series enamel and frame insulation capacitance for the controlled winding at frequencies f₁ and f₂ of the electromagnetic field respectively, p is a number of slots in the magnet core to which the controlled part of the winding is inserted; S is a square area of the slot; ε₀=8.854187·10^-12 is an electric constant; ε_e(f₁), ε_e(f₂), are the dielectric capacitance values for the enamel film of the winding wire at frequencies f₁ and f₂ of the electromagnetic field respectively; ε_f(f₁), ε_f(f₂) are the dielectric capacitance values for the frame insulation at frequencies f₁ and f₂ of the electromagnetic field respectively; d_e is thickness of the enamel insulation of the wire; d_f is thickness of the frame insulation; thereafter according to measurement results of $$\frac{\lg {\epsilon }_{ic}\left(f_2\right)}{\lg {\epsilon }_{ic}\left(f_1\right)}$$ value dryness degree of the insulating compound in each controlled winding is determined against the dryness curve.

EFFECT: excluding necessity of self-capacitance measurements for windings at three frequencies with use of reference inductance with simultaneous and essential simplifying of measurements due to exclusion of manufacture and use for the purpose of control of such elements as a current stabiliser, a heating time metre and metre of windings temperature increment in heating process.

1 tbl, 4 dwg asd - as