IEEE Std 433:2009 pdf free download

IEEE Std 433:2009 pdf free download.IEEE Recommended Practice for lnsulation Testing of AC Electric Machinery with High Voltage at Very Low Frequency.
4.7 Sectionalizing the winding
When feasible, cacti phase should be isolated and tested separately with other phases grounded. The two ends of each phase should be connected together and grounded while the other phase is under test. Testing one phase at a time gives a comparison between phases that is useful in evaluating the condition of the winding and is useful for historical records. Testing all phases at one time is suggested for machines only if the neutral connections are inaccessible. In this case, the three line leads of the winding should be connected together to avoid surges at an open end in the event of failure or Ilashover. When testing all phases at one timc, only ground insulation is tested, and no test is made on the phase-to-phase insulation as when each phase is tested separately with other phases grounded.
The two ends of the circuit under test should be connected together. The ends of the circuits not under test should be connected together and to ground, or if in different locations (such as hydrogenerators with distributed neutrals) may be connected to the machine frame and local ground.
4.8 Equipment clearances and area isolation
Prior to performing high-voltage tests, the equipment to be tested must be deenergiied and disconnected from other equipment or parts of the circuit that will not be tested. The test specimen must be placed under the appropriate clearances to block potential sources of hazardous energy.
Physical barriers, safety tape. warning signs. andor observers must be put in place to restrict access to the testing area and the equipment under test. This safety measure is necessary to prevent personnel from inadvertently coming into contact with energized equipment.
Test participants and others in the vicinity should be notified that high-voltage tests arc going to be perfornied. Flashing lights, loudspeakers, two-way radios, and other equipment are sometimes used to communicate with personnel in the area.
4.9 Grounding precautions
All specimens should be properly grounded so that personnel hazards are minimized. Ungrounded objects in proximity to the equipment under test should be solidly connected to ground to prevent induced voltages.
Appropriate grounding provisions should be available for use upon completion of the test and in case of an emergency during the test. Ground connections must be strong and secure to minimize the risk to personnel. As a minimum, the current capacity of the uninsulated ground leads should exceed that necessary to carry the maximum possible ground current. Stranded wire size 13.30 mm (AWG 6) or larger is recommended. The clamping device used to connect the ground wire to plant ground should have sufficient mechanical strength to prevent unintentional disconnection from ground. The continuity of ground connections should be visible; tape and rubber clip insulators should not be used on ground connections. The wire strands should be visible at tugs and clips and not covered in any way.