GENERATOR FIELD Sample Clauses

GENERATOR FIELD. 11.8.2.2.1 OVERSPEED AND BALANCE (OBSERVE) OVERSPEED TEST--The overspeed test is intended to expose the components of the field assembly to forces higher than normal and demonstrate the ability of the field assembly to withstand such forces. The field is set up in the high speed balance facility, it is held for three minutes at a speed 20% above the rated speed of the unit. HIGH SPEED BALANCE--The generator field will undergo a high speed balance. The primary objective of precision balancing is to reduce the residual unbalance of the field to the lowest possible level. The approach used in balancing fields is called modal balancing. Each mode of vibration, or critical speed, is balanced in turn, starting with the lowest speed, on first mode. The process proceeds to each critical in turn from the first to the highest critical within the operating speed range. After all criticals are balanced to a small residual vibration level, balance at rated speed is evaluated. 11.8.2.2.2 FINAL ELECTRICAL TEST (OBSERVE) - WINDING RESISTANCE MEASUREMENT--The dc resistance of each phase is measured with a low resistance bridge. The winding temperature is also measured. - INSULATION RESISTANCE MEASUREMENT--Prior to the final winding high potential test, the insulation resistance over a ten minute period is measured with a 500 volt dc insulation tester. - High-Potential Test--The windings of the field are tested by applying 10 times the rated field voltage but not less than 1500 volts ac between the field winding and ground for field voltages of 500 volts or less. For fields rated greater than 500 volts, the test voltage is twice the rated voltage plus 4000 volts ac. This test is done per GE standard which meets or exceeds IEEE 115 and ANSI C50.10.