Insulation tests

IEEE 43 places special emphasis on determining the insulation condition of such machines before energizing and even before conducting a high-voltage test. This can be determined by the insulation test as noted below. 

Before conducting the insulation test one should ensure that there is no self-induced e.m.f. in the windings. It is recommended that the windings be totally discharged by grounding them through the frame of the machine before conducting the test. 

Practice for insulation testing. Large a.c. rotating machines w4th high voltage at very low frequency. 

Methods for Testing Shellac Used for Electrical Insulation Test Methods Relating to Moisture Absorption Test Methods Relating to Coefficient of Thermal Expansion Test Methods for Testing Rubber Cements... 

Heat losses to the ambient are generally small for a well-insulated test section. However, they could represent a good fraction of the heat transfer rate in the test section at low airflows. A proper calibration is essential to determine these heat losses. 

Figure 8 shows the results of these calculations as a plot of test-tank apparent thermal conductivity against compressive load on the insulation. Test-tank jKapparent varied from a value of 90 x 10 Btu/hr-ft- F, at the ground-hold condition, down to about 8 x lO" Btu/hr-ft-°F, at the lowest pressure load on the insulation. Also shown in Fig. 8 is the previously published data for Linde SI-62, which fall below the present test results. Note that on the lower curve is plotted performance of a pure insulation material, while the upper... 

Standard fittings and mountings such as breather (with drying agent), junction box for (incoming) leads, and outgoing (cable/bus bar contacts) connection. Necessary test certificates for hysteresis losses at various loads, insulation tests for the windings and shell of the unit. 

Bunched wires and cables are tested according to lEC Publication 332-3 (1982, Modification 1984) in a thermally insulated test rig comprising a vertical test chamber having a width of 1000 mm, a depth of 2000 mm and a height of 4000 mm with an air inlet aperture of 800 x 400 mm at the base and with a smoke outlet of 300 x 1000 mm at the top (Fig, 3.125a). The bunch of 3.5 m long pieces of cables is fixed to a steel ladder attached to the rear wall of 1000 x 4000 mm. The number of cable pieces... 

Test criteria include ignition time, dripping, and subsequent burning. The insulation test sample is moulded on a movable fixture and pressed against the hot wire loop with a force of 1 N. The penetration distance is restricted. The exact temperature of the wire loop is measured with a miniature thermocouple. 

Adhesives Relative to Their Use as Electrical Insulation, Testing (D 1304)... 

The apparatus used in this study consists of an environmental control system and a cryogenic insulation test specimen assembly. The environmental control system, illustrated in the schematic... 

Fig. 6. Cryogenic insulation test apparatus - environmental control system.

Figures 7 and 8 are drawings of the cryogenic insulation test specimen assembly. The compartmented aluminum tank, which can accommodate 6 insulation specimens (see Fig. 7), measures 1.8 by 0.6 m (2 by 6 ft) and is 3.9 cm (1.53 in) thick. The tank was fabricated from 0.6 cm (2 ft) sections of an extruded web core structural plank. The webs form a series of cells which measure 61 by 3.9 by 4.5 cm (24 by 1.53 by 1.78 in). The cells are connected at the bottom of the tank to form separate test and guard compartments (see Fig. 8). The insulation specimens span a test compartment and one-half a guard compartment at both ends. This...

At zero power input to the insulated test section virtually adiabatic conditions existed and the wall temperature was the same as the bulk fluid temperature. Thus AT = Tb = 0 and the average of the wall temperatures equalled the... 

Insulation tests—resistance between windings and shell of the unit. 

The measurement of triboelectric charge generation is well known for its variability where relative humidity, surface contamination or abrasion, tress configuration, and other variables have to be strictly controlled. Even with the combing of up to five replicate tresses and five successive determinations, Lunn and Evans report a 95% confidence interval of 15%. The apparatus that Lunn and Evans used is shown in Figure 28. The insulated tress is combed with a hand-held insulated test comb, and after the appropriate number of strokes, the tress is released into a Faraday cage connected to an electrometer. The whole setup is enclosed in a box in which temperature and humidity are controlled. 

Paint/alloy evaluation (fastener insulation test)... 

Surface insulation tests utilize two interleaved Cu combs with an imposed dc bias across the combs. These combs may be designed into existing boards or a coupon such as the IPC-B-25 test board shown in Fig. 57.24 may be used.The measured resistance (ohms) from the comb pattern can be converted to surface resistivity (ohms per square) by multiplying the measured... 

High-voltage testers, using either a battery or a hand-cranked generator, are used in testing insulation. Testing voltages may exceed 5000 V. 

Fig. 17.7 Insulation testing between phase(s) and neutral conductors and earth.

Fig. 17.8 Insulation test between each phrase or neutral conductor and the other conductors connected together.

ASTM E2235-04, 2012. Standard test method for determination of decay rates for use in sound insulation test methods. American Society for Testing and Materials. 

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