Voltage impulse withstand

This is a resin-rich system. The stator is wound with pre-formed coils on similar lines as noted above. After thorough testing on each coil for the polarization index and dissipation factor (tan S), as discussed in Sections 9.5 and 9.6, and the impulse voltage withstand test, as discussed in Section 11.4.9, the individual coils are completely cured and toughened before inserting them into the slots. The rest of the process is as noted earlier. 

Impulse voltage withstand test of the insulation system for rated voltages 2.4 kV and above for machines wound with formed coils 11/261... 

Principal considerations in framing the specification for impulse voltage withstand level and underlying the test procedures 11/262... 

VI995 Rotating electrical machines Impulse voltage withstand levels of rotating a.c, machines with form wound stator coils 14222/1995 BS EN 60014-15 ... 

Impulse voltage withstand level for assemblies having a system voltage of 2.4 kV and above, according to Section 14.3.4. 

Between line and load fixed terminals of each phase. ANSI-C37/20C recommends this test to be conducted at a value 10% higher than specified in Table 14.2 for both power frequency and impulse voltage withstand tests. 

Leaving only a small part (0,05 Joules) for the machine to absorb, which it should be compable to do in view of its own impulse voltage withstand capability at = 14 kV,... 

With this particular arrester, the motor has to be specially designed for the higher level of FOW impulse voltage withstand. But the manufacturer can always modify the protective characteristics of the arrester, depending upon the system s requirements. The matter may therefore be referred to the manufacturer for recommendations. The arrester may be fitted with a 0.25, uF surge capacitor in parallel, to reduce the steepness of the FOW (for the arrester of example 17.5, it is 14/0.2 kV/jUS) to a safer value. 

Vf profile becomes flat (constant) and less than impulse voltage withstand capability (BIL) of the equipment under protection... 

For non-effectively grounded systems, having a GFF of more than 1.4, a higher level of insulation (BIL) will be essential for all equipment being used on the system to withstand a higher level of a one-minute power frequency voltage test as well as an impulse voltage withstand test if such levels (Lists I, II and III) are prescribed in the relevant standards. If not, then it may be assumed, that the prescribed test values take account of such an... 

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