Caltech Electrical Grid Modernization Richard J. Bravo, Campus Senior Electrical Engineer California Institute of Technology
Mike Anchondo, Campus Electric Supervisor California Institute of Technology
1200 East California Boulevard, M/S 0-66 Pasadena, CA 91125 rjbravo@caltech.edu (626) 395-2155
1200 East California Boulevard, M/S 0-66 /TP75 Pasadena, CA 91125 mike.anchondo@caltech.edu (626) 395-4999
Caltech Facilities began the Caltech Electric Grid Modernization project with the replacement of four transformers. Replacing the six-decades-old transformers will provide safe and reliable power to the Caltech community for many decades to come. Facilities will perform this electric grid modernization in four phases, as described below. The first phase has been completed. Phase 1: Electrical Substation Transformer Replacement Four Caltech distribution transformers at electrical substation #1 (behind Gates-Thomas) and substation #2 (behind Steele) have been replaced as of April 2022. These vintage transformers were manufactured in the early 1960s so it was time to replace them with new units. Substations #1 and #2 supply power to about 80 percent of the Caltech campus. The new transformers have the following advantages over the vintage transformers: 1) They use FR3 oil that is biodegradable, nontoxic, and non-hazardous; older transformers contained thousands of gallons of mineral oil that had some PCB contaminants. 2) They are more efficient; older transformers had about 80% more mass and had higher power consumption. 3) They have the same configuration as the substation #3 and substation #4 transformers (Delta/Wye), which will allow Caltech to parallel all Caltech substation transformers in the future; vintage transformers were Delta/Delta that did not allow all Caltech substations to be paralleled. 4) They have infrared windows to safely assess cable termination point integrity while energized. The older transformers did not have the means to accomplish this without an extended outage to the transformer. OLD TRANSFORMER NEW TRANSFORMER
Fig. (left) vintage transformer; Fig. (right) shows the new transformer with Caltech Electricians Group and Senior Electrical Engineer.
June 1, 2022
1
Phase 2: Electrical Substation Switchgear Replacement Caltech electrical substation #1 and substation #2 switchgear are from the early 1960s and have reached the end of their service life. The new switchgear will enhance safe and reliable power to Caltech buildings. Each switchgear will cost approximately $3 million (hardware cost) and has a 50week lead time for design, manufacture, and delivery. Substation #1 switchgear is expected to be delivered by summer 2023. Soon after installation begins, Caltech Facilities will schedule outages to move building power circuits from the old switchgear to the new switchgear. Switchgear replacement will happen by the 2nd and 3rd quarters of 2023. Substation #2 switchgear will be ordered by the 3rd quarter of 2022 and will be installed between the 3rd and 4th quarters of 2023. Facilities will also be scheduling outages to move those building power circuits from the old switchgear to this new switchgear. The outages will be scheduled weeks in advanced and we will work closely with building managers for a smooth transition. All outage durations will be kept to a minimum, in most cases less than several minutes. The new electrical substation switchgear will have the following advantages over the old switchgear: 1) They will be equipped with electronic protection relays; most of the existing protection relays are electro-mechanical and protection functions are limited. 2) They will be equipped with infrared windows to assess cable termination point integrity while energized; older switchgear does not have the means to assess termination health and require outage to perform this work. 3) They will have high accuracy electric meters (waveform and rms) to allow troubleshooting after events (short circuits, interruptions, etc.); older switchgear only have RMS values, which are very limited for troubleshooting. 4) They will be protected in an enclosed, air-conditioned room; existing switchgear are located outdoors. During or before the substation switchgear replacement, the substation #1 PWP 17,000-volt switches will be relocated inside the substation vault room where malfunctions can be properly contained. In addition, some buildings may be provided a second feeder circuit to minimize outages during the transition to the new switchgear. Phase 3: Distribution 2,400-volt Non-Shielded Cables Replacement Caltech has some old (> 50 years) distribution 2,400-volt circuits cables that are non-shielded. Although these non-shielded cables are much easier and cheaper to install, they have great disadvantages over shielded cables, such as: 1) They do not carry short circuit electrical current in order for protection relays to work properly; shielded cables carry short circuit electrical current; therefore, protection devices will work fast and properly to protect the lines during short circuits. 2) They have high stress on their insulation; shielded cables limit voltage stress on their insulation, which makes these cables last longer. 3) They have some leakage electrical current that could become a safety hazard for high voltage workers; shielded cables dissipate insulation leakage electrical current into the grounded shield. June 1, 2022
2
4) They have capacitive electrical current that could become a safety hazard for high voltage workers; the new shielded cables remove capacitive electrical current. During or soon after the 2,400-volt non-shielded cables are replaced, Caltech Facilities will link substation #1 to substation #4 and substation #2 to substation #3 to add an extra layer of redundancy. Currently, substation #1 and substation #2 are linked at the 2,400-volt level, which provides redundancy. This feature has been utilized many times to allow for maintenance and repair of main service equipment without affecting service to the Caltech campus, most recently when the new transformers were installed. Phase 4: Automatic Power Factor Correction Caltech has three dedicated 17,000-volt lines that come from Pasadena Water and Power (PWP). Caltech has been incurring power factor penalties from PWP. This can be mitigated by installing capacitors at the substation and local levels. Resolving the power factor issue will: 1) Reduce/eliminate power factor penalties. 2) Improve efficiency in the 17,000-volt and 2,400-volt lines so that more power can be pushed through these lines if needed. 3) Improve campus system voltage.
June 1, 2022
3