Page 20 - PD Experience on 3-5kV

Bipolar Machine PD
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
300 300
200 200
100 e [m V ] 100
5.6 MODERATE BUT CHANGE IN 0 0
P ulse M agnitud
PATTERN -100 -100
Plant: 4kV Induction Motor, 1250hp -200 -200
Original test date was: May 2009 (periodic) -300 -300
PD Values: Qm+ 95mV, Qm- 125mV 0 45 90 Phase Angle [deg] 225 270 315 360
135
180
Pulse phase analysis: primarily internal PD, but may be Jun 2013
interphasal Bipolar Machine PD
Follow-up monitoring: initial increase but since Jun 1 to 3.16 pps 3.16 to 10 pps 10 to 31.6 pps 31.6 to 100 pps
2011 primarily stable [Figure 12] 100 to 316 pps 316 to 1000 pps > 1000 pps Subset 8
Comparison of Jun 2011 to Oct 2013 showed similar 300 300
100 e [m V ]
magnitudes but a significant change in PD pattern 200 200
New PD Values: Qm+ 132mV, Qm- 161mV 100
P ulse M agnitud
Current situation: continue to monitor, but consider 0 0
additional testing because of the change in PD pattern -100 -100
-200 -200
-300 -300
0 45 90 135 180 225 270 315 360
Phase Angle [deg]
Jun 2011

Bipolar Machine PD
5.7 INCREASE BUT NOT PD 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
• Plant: 4kV Induction Motor, 1.865MW 150 150
• Original test date was: Sep 2007 (periodic) 100 V ] 100
• PD Values: Qm+ 16mV, Qm- 8mV 50 50
• Pulse phase analysis: negligible PD P ulse M agnitude [m 0 0
• Follow-up monitoring: increase in Apr 2014 (see -50 -50
below) -100 -100
• Comparison of Nov 2013 to Apr 2014 shows a -150 -150
single source at or near the zero crossings that has 0 45 90 135 180 225 270 315 360
reversed polarity. This is not PD. Phase Angle [deg] Apr 2014
• Decision: continue to monitor
• New PD Values: Qm+ 56mV, Qm- 88mV
• Current situation: no problems indicated

Trend Analysis Plot Qm only Bipolar Machine PD
1 to 3.16 pps 3.16 to 10 pps 10 to 31.6 pps 31.6 to 100 pps
Machine Qm+ Machine Qm- Activity Qm+ Activity Qm-
90 100 to 316 pps 316 to 1000 pps > 1000 pps Subset 8
80 150 150
70 100 V ] 100
60 50 50
50 xis 0 0
40 A
30 Y P ulse M agnitude [m -50 -50
20 -100 -100
10
0 -150 -150
2009 2010 2011 2012 2013 2014
135
180
X Axis 0 45 90 Phase Angle [deg] 225 270 315 360
Long-term Trend Nov 2013

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18 | P age