Surge testing method in decompressed atmosphere for a small-size electric machine and apparatus thereof

• US 5,594,348 A
• Filed: 05/25/1995
• Issued: 01/14/1997
• Est. Priority Date: 06/17/1994
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Iijima, Yasuo, Tsubokawa, Masahiro
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): DO, DIEP N
• Application Number:
  US08/450,638
• Time in Patent Office: 600 Days
• Field of Search: 324/522, 324/523, 324/527, 324/536, 324/541, 324/544, 324/545, 324/546, 324/551, 324/772, 324/388, 340/646, 340/647, 340/648
• US Class Current: 324/546
• CPC Class Codes: G01R 31/1227 of components, parts or materials G01R31/1209, G01R31/1218, G01R31/18 take precedence; circuits therefor G01R31/14; testing vessels of electrodes G01R31/16
• CPC Class Codes: G01R 31/16 Construction of testing vessels; Electrodes therefor
• CPC Class Codes: G01R 31/34 Testing dynamo-electric machines

Abstract

To carry out a non-destructive test for testing insulation of a small-size electric machine having a coil, a surge voltage is applied to the coil of the electric machine mounted in a decompression tank whose inner pressure is kept from 15 to 25 [Torr] so as to generate glow discharge in case there exists a flaw in the coil.

Claims

1. A non-destructive insulation testing method for a small-size electric machine having a coil, comprising the steps of:

mounting said electric machine in a container whose inner pressure is kept from 15 to 25 [Torr];

applying a surge voltage to said coil; and

detecting whether a glow discharge is generated or not from said coil.

2. A non-destructive insulation testing method in accordance with claim 1, wherein

said surge voltage is applied to said coil in a first direction which is from a beginning point of winding to an end point of winding in said coil and in a second direction reverse to said first direction.

3. A non-destructive insulation testing apparatus for a small-size electric machine having a coil, comprising:

a container for mounting therein said electric machine, said container having an inner pressure kept from 15 to 25 [Torr];

surge applying means for applying a surge voltage to said coil; and

surge detection means for observing a surge voltage waveform appearing between both ends of said coil, said surge detection means including;

means for measuring a first time period which is correlative with a wavelength of said surge voltage waveform in a state that a reference surge voltage is applied to said coil;

means for measuring a second time period which is correlative with a wavelength of said surge voltage waveform in a state that a surge voltage higher than said reference surge voltage is applied to said coil;

means for obtaining a difference between said first time period and said second time period; and

means for comparing said difference with a reference value.