Caltech Facilities Newsletter Caltech Electric Grid Modernization Update Richard J. Bravo, Senior Electrical Engineer California Institute of Technology 1200 East California Boulevard, M/S 0-66 Pasadena, CA 91125 rjbravo@caltech.edu (626) 395-2155
Caltech Facilities is continuing the Caltech Electric Grid Modernization with the replacement of 2,400-volt switchgears from the early 1960s. This electric grid modernization will be performed in multiple phases, as described below. Accomplishments: 1) In Phase 1, electrical substation #1 and #2 transformers were replaced. These transformers were from the early 1960s and supply power to a vast number of Caltech buildings. 2) Replaced an oil leaking 17,000-volt switch and more than 5,000-feet of cable from the 1930s. 3) Provided protection to the 17,000-volt circuits feeding Satellite Plant with resettable fault interrupters (RFI). 4) Relocated Substation#1 17,000-volt switches from an adjacent pedestrian area to an enclosed safe area where malfunctions can be properly contained. 5) Replaced “T-Bodies” with actual “17,000-volt switches.” Switches will provide redundancy because circuits now can be sectionalized during emergency or abnormal conditions. 6) Replaced 3 protection relays at substation #3 due to premature failures. T-Body
SWITCH
Fig. 1 (left) T-Body, (right) Typical Switch where multiple inputs can be switchable.
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Phase 2: Electrical Substation 2,400-volt Switchgears Replacement (timeline 2024 & 2025) Present Caltech electrical substation #1 and substation #2 distribution network switchgears 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. These switchgears were ordered in late 2021 and early 2022 respectively. They were scheduled to be delivered in 2023 but due to supply chain delays they will be delivery summer 2024 and fall 2024. Substation #1 switchgear is expected to be delivered by summer 2024. 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 after the 2nd quarter of 2024. Substation #2 switchgear is expected to be delivered by 3rd quarter of 2024 thereafter will begin its installation. Facilities will also be scheduling outages to move building 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 many cases less than 10 minutes. The new electrical substation switchgear will have the following advantages: 1) Equipped with electronic protection relays for very fast protection; existing OLD protection relays are mostly electro-mechanical and their protection functions are limited. 2) Equipped with infrared windows to assess cable integrity while energized; existing switchgear requires outage to perform this work. 3) Equipped with high accuracy electric meters to allow troubleshooting after events; older switchgear only has RMS values that are very limited for troubleshooting capabilities. 4) Protected in an air-conditioned switchgear room; existing indoor switchgears are located outdoors. Old Switchgear
New Switchgear
Fig. 2 (left) vintage existing 2,400-volt switchgear, (right) new 2,400-volt Switchgear Prototype.
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Phase 3: Substation#3 Protection Relays Replacement (timeline 2024-2025) Caltech Substation#3 had multiple 20+ year-old relays failures between September and November 2023. These relays just stopped working and in 2 events multiple buildings (BI, Braun Lab, Schlinger) experienced outages. The existing relays have been obsoleted by the manufacturer. Facilities replaced the failed relays with same type relays for now plus acquired some for spare purposes. It is in Facilities plans to upgrade all Substation#3 protection relays with present safe and reliable technology and will require no outages for these replacements. The new relay technology can: 1) Accept voltage inputs, existing relays do not have voltage inputs 2) Record events to allow prompt troubleshooting, existing relays do not record events 3) Record voltage and current, existing relays do not have recording capabilities 4) Display real time measurements, existing relays cannot display any voltage/currents. 5) Secure communications protocol, existing relays do not have secure communications protocol 6) Provide touch screen interface where users can navigate through the different features Existing Relay
New Relay
Fig. 3 (left) existing older relays, (right) new electronic relays with touch screen interface.
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Phase 4: 17,000-volt Automatic Transfer Switches and Controls Replacement (timeline 2025) Caltech has three dedicated 17,000-volt PWP circuits from three different PWP substations. These three dedicated circuits rely on Automatic Transfer Switches “ATS” to transfer load in case of circuit failures. The existing PWP ATS technology is older, slow, and not reliable. The three existing ATS will be replaced with new ATS technology and will require no outages. The new ATS and its new digital controller can. 1) Transfer within 0.1 seconds, existing ATS if not blocked will transfer in about 10 seconds 2) Disregard inrush currents from loads, old ATS can block from operating after high inrush currents. Caltech suffered outage due to ATS blockage. 3) Control in a precise, secure, and reliable manner, old ATS controls are electromechanical. 4) Communicate if needed in a safe and reliable manner Existing ATS
New ATS
Fig. 4 (left) existing ATS, (right) new dielectric fast Automatic Transfer Switch.
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Phase 5: Distribution 2,400-volt Non-Shielded Cables Replacement (timeline 2026) Caltech has some old (> 50 years) distribution 2,400-volt circuits cables that are nonshielded. 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; shielded cables dissipate insulation leakage electrical current into the grounded shield. 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 6: 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.
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