FFXI Haven - Ваш Источник #1.

Power factor tests have little value when made at freezing temperatures.

(3) Relative humidity should be less than a maximum of 80 percent.

(4) Insulation being tested should be dry and clean.

(5) Insulation temperature must be known and should not be less than the air temperature; otherwise, condensation will take place and hot-collar losses will be high because of surface leakage. Temperature may be measured with a thermometer in contact with the porcelain.

(6) Current leakage by creepage along insulation surfaces should be eliminated by the application of the proper guard circuit of the tester. Guard circuits vary with testers of different types, and the manufacturer's recommendations should be followed.

e. Test comparisons. In order to yield better results that can be compared, power factor tests on the same item should be made at the same voltage and frequency. Measurements at different temperatures should be corrected to 68 degrees F (20 degrees C) to facilitate comparisons and establishment of a power factor trend. See table 3-3 for correction factors.

(1) Power factor is a "worst condition" value, and it is necessary to isolate bushings from the rest of the equipment being tested only if the test indicates trouble. In such a case, each item must be tested separately to determine which is failing; a

Table 3-3. Temperature correction factors for power factor1

Temperature Correction factor (K)

50°F (10°C).................. 1.25

59°F (15°C).................. 1.11

68°F (20°C).................. 1.00

77°F (25°C).................. 0.89

86°F (30°C).................. 0.80

95°F (35°C).................. 0.71

104°F (40°C)................. 0.65

113°F (45°C)................. 0.57

122°F (50°C)................. 0.51

131°F (55°C)................. 0.46