Hipot tests are frequently applied to stator windings to assure the electrical insulation in winding is with good quality.
However,several questions are frequently raised: When should a hipot test be applied? Which hipot test should be applied? What should be the hipot test levels? Does hipot test damage a good winding?
Hipot test is performed to asssure that the winding insulation has a minimum level of electrical strength to survive electrical stresses in normal service.
Hipot tests are performed with three different types of voltages. The AC hipot tests,DC hipot tests and proof test
Do Hipot Tests Damage a Good Winding?
The answer is NO to this question raised often by managers,
who have to approve the hipot tests. Maintenance hipot tests
do not introduce any significant degradation in a machine with
good insulation system. Machines, which failed a hipot test,
have always been found to have a poor insulation system in an
examination following the failure.
When to Apply (or not Apply) Hipot Tests?
New windings: For new windings (also coils), the hipot tests
are and should be used universally as acceptance and quality
assurance tests. Generally AC hipot tests are used with other
diagnostic tests such as insulation resistance (IR), polarization
index (PI), dissipation factor (DF), and/or partial discharges
(PD).
Windings in service: To reduce the risk ofa costly forced
outage, a regular maintenance program, including hipot tests,
is necessary. The winding may be tested during maintenance
outages often every 3 to 6 years and somewhat longer for large
generators.
Contact:Emily
Email: emily@motor-machinery.com
Skype: motor.machinery
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Website: http://www.motor-machinery.com; http://www.coilswinding.com
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Emily