1. New Capacitor Analysis and Maintenance Process at Centerpoint Energy Presented at SWEDE Conference 2005 by Richard Moffatt

4. Why do we have Capacitors? (Power Factor = KW / KVA) KW’s KVARS KVA

5. Process Improvement Recommendation ·Goal: Reduce Capacitor Maintenance Expense ·Send capacitor crews directly to circuits with problem capacitors, and thus eliminate their random search for failed capacitors (Time, temp, fixed banks). ·Develop program (CAPSURE) to detect capacitor banks that are switching but experiencing a partial failure on 1 or 2 phases. Uses load survey data for circuits (KW & KVAR) on 15 minute intervals. ·Produce “Bank Shot Report” ·Produce “Low Power Factor Report”

6. Bank Shot Report ·Identifies KVAR changes greater than the minimum threshold value based on the smallest cap on circuit. ·Looks for single phase or two phase failures. ·Two tests: ·Magnitude of KVAR change (15 min intervals) compensated by KW load change. ·KVA phase angle change. ·In most cases, can infer the probable bank size based on the magnitude of the change in KVARS. ·Pull in caps on circuit from Capacitor Database. ·Pull in PF at peak for identified circuits.

7. 52386317593852236449116710211386137110501503 AR 4212:4697.596.598.097.5602653696390623054576697147411231532145911381619 BA 0110:0110098.198.698.9123213901464123714271506277393229251-7-244 BA 0120:0197.398.198.698.914061601157514481596151630324-239356462266 BA 0410:31-100100.0-99.8-99.6108998997811371000984261277198287-118-181 BA 0417:1699.3100.0-99.8-99.6179116331427186516271432219-228-42432420855 BAR435:1698.994.995.395.1334132683020347233563151802248-72802306379 BAR4310:3196.894.995.395.15690 5165579256755150188213281503194012981036

10. Report Sent to Field Forces

11. Low Power Factor Report ·Pulls in power factor at peak, 4:46 PM, for every circuit on the system for 5 consecutive days. ·Pulls in caps from capacitor database. ·Calculates the theoretical power factor with all caps on, as well as the number of KVARS off-line. ·The key is to look for circuits with a low power factor over those 5 days (less that 98%) and with a meaningful magnitude of KVARS off-line. ·There is no reason to send a crew to a circuit with a poor power factor if all of the caps are working, and there is no reason to send a crew to a circuit with excellent power factor even if some of the caps are off-line.

13. Report Sent to Field Forces

14. Results ·Piloted this effort during the 2nd half of 2004. ·Good success rate. ·In almost all cases, the crews were finding problems on the circuits identified. ·Crews were entering their work into the Capacitor Database. ·Needed to develop tracking mechanism and provide monthly reports on the progress of the crews.

15. Issues ·Needed to integrate this analysis effort into larger capacitor maintenance / capacitor construction program. ·Issues: ·Capacitor crews & supervision had other priorities. ·Work orders & construction of new capacitors was not timely. ·Material shortages at certain times of the year (Long lead times on materials, plus inventory reduction). ·New products such as vacuum switches & cutouts. ·The creator of Capacitor Database left the company.

16. Capacitor Program ·Capacitor construction strategy ·Capacitor material strategy ·Capacitor maintenance strategy

17. Capacitor Construction Strategy Established timeline for new capacitor construction: 1. Identify & issue material requirements to Purchasing based on development plans by 9/1 2. Issue next year’s construction schedule by 9/1 3. Engineering to write work orders by 10/30 4. Material purchases to be driven by bill of materials on work orders via SAP 5. CW Utilities to assemble materials in kits for each work order & deliver to S/C via cross-dock with central stores 6. Complete construction by 3/31 7. Track orders via SAP (10/1 - 3/31)

18. Capacitor Construction Strategy Benefits: Caps completed sooner in the year so crews will be available for maintenance as the weather warms up. (Previous focus was simply to get the banks built by 6/1) Materials for construction will ordered based on material requirements of work orders. Better utilization of materials since construction crews will not be taking the materials needed for maintenance or for other construction jobs.

19. Capacitor Material Strategy Goal: Accurately identify material needs for new construction Accurately identify material needs for maintenance Acquire materials on a more timely basis Utilize better materials where necessary

20. Capacitor Material Strategy Revised inventory purchase thresholds based on: 1. Annual & monthly maintenance requirements (avg & peak values to account for weather impacts) 2. Lead time for each material Perform monthly review of materials on hand, on order and at CW Utilities. Order specific materials if necessary. Establish metrics on material acquisition and usage to measure how effective we are on material strategy.

21. Capacitor Material Strategy Metric: Fill rate = % of time material is available when you need it. 2004 overall fill rate was 84% Goal for capacitor materials is 98 - 100% Fill rate will be calculated for each material item

22. Capacitor Maintenance Strategy ·Established priorities for capacitor crews: 1. Banks identified by Capacitor Analysis 2. Banks identified by RCCS 3. Switching orders for banks taken out of service 4. Banks with hot spot identified by infra-red 5. Field reports of banks out of service 6. Construction for planned capacitor work 7. Other work ·Held meetings with crews & their management to review priorities. ·Established flow chart for entire maintenance process.

24. Conclusion ·Implementation currently underway. ·Will see how it works in the 2005 - 2006 season.