Page 19 - PD Experience on 3-5kV
P. 19

5.5  SEASONAL PD
                                                                                       Bipolar Machine PD
                    •   Plant:  4kV Induction Motor, 1250hp                    1 to 3.16 pps  3.16 to 10 pps  10 to 31.6 pps  31.6 to 100 pps
                    •   Original test date was: Mar 2009 (periodic)            100 to 316 pps  316 to 1000 pps  > 1000 pps  Subset 8
                    •   PD Values:  Qm+ 198mV, Qm- 372mV                   750                                750
                                                                           250 e [m V ]
                    •   Pulse phase analysis:  High primarily internal PD   500                               500
                    •   Follow-up monitoring: initial decrease followed by an                                 250
                                                                          P ulse M agnitud
                        apparent increase (see below)                       0                                 0
                    •   Comparison of Mar 2009 to Feb 2011 showed no change   -250                            -250
                        in magnitude or pattern, but the Jun 2009 levels were   -500                          -500
                        lower in magnitude (see below)                    -750                                -750
                                                                                        135
                    •   Decision:  continue to monitor                        0  45  90  Phase Angle [deg] 225  270  315  360
                                                                                            180
                    •   New PD Values: Qm+ 227mV, Qm- 314mV                                             Mar 2009
                    •   Current situation:  no problems indicated

                                                   Trend Analysis Plot Qm only
                                         Machine Qm+                            Machine Qm-
                       350
                       300
                       250  xis
                          A
                         Y
                       200
                       150
                        Jan 2009  Apr      Jul      Oct    Jan 2010  Apr      Jul     Oct    Jan 2011
                                                               X Axis

                                   Bipolar Machine PD                            Bipolar Machine PD
                          1 to 3.16 pps  3.16 to 10 pps  10 to 31.6 pps  31.6 to 100 pps  1 to 3.16 pps  3.16 to 10 pps  10 to 31.6 pps  31.6 to 100 pps
                          100 to 316 pps  316 to 1000 pps  > 1000 pps  Subset 8  100 to 316 pps  316 to 1000 pps  > 1000 pps  Subset 8
                      750                                750        750                                750
                      250 e [m V ]                       250        250 e [m V ]                       250
                      500                                500        500                                500
                      P ulse M agnitud                              P ulse M agnitud
                      -250 0                             0 -250     -250 0                             0 -250
                      -500                               -500       -500                               -500
                      -750                               -750       -750                               -750
                         0  45  90  135  180  225  270  315  360       0   45  90  135  180  225  270  315  360
                                   Phase Angle [deg]                             Phase Angle [deg]
                      Jun 2009 (summer results – significantly less)   Feb 2011 (winter results – same as Feb 2009)
                              Qm+ 177mV, Qm- 216mV                          Qm+ 227mV, Qm- 314mV






















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