13.8 kv - Power Operated
Outdoor Distribution
The sixty-five bays of 13.8.kv S&C Metal-Enclosed
Switchgear pictured above and highlighted in this photo sheet provide switching and protection for the multitude of individually segmented process-related loads at a large industrial facility. Segmentation of each load is essential for immediate isolation of only the faulted section without losing power to the other loads, which improves control of operations for efficient production.
Configured into two lineups (a 32-bay and a 33-bay, which are shown in facing rows above but placed in one row at the installation), each assembly includes three switched and fused bus sections, and features power operation of every feeder circuit. In addition, all feeder bays include open-phase detectors to effect automatic isolation of three-phase load circuits in the event of single-phasing conditions caused by blown feeder fuses. Furthermore, operation of each feeder switch can be initiated from a remote location.
In each lineup, control power for operation of the switch operators and open-phase detectors is provided by a 48-volt dc battery pack. A battery charger with
120-volt input/48-volt output supplies energy to keep the batteries charged. A single-phase 15-kva control power transformer provides input to the charger, and supplies power for the strip heater in each bay and for all other low-voltage components in the lineup.
Because of the large number of bays on this order, the user established particular requirements to facilitate shipment, handling, and installation. For this purpose, S&C built special lifting beams-one suitable for lifting up to 6 bays simultaneously and another for lifting an 11-bay group. The rigidity of
S&C’s enclosures made hoisting such large groups of bays possible. A major contributor to such rigidity is the 4-inch channel base furnished on every bay of
S&C switchgear. The substantial material content of this base also made it feasible for the user to weld each bay to steel reinforcing angles embedded in the concrete pad at the installation-a somewhat unique installation technique the user prefers over anchor bolts.
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The one-line diagram illustrated above depicts the power system to the installation from the serving utility’s transmission system. The serving utility has established a substation adjacent to the installation. Power enters the substation through two 230-kv, 1600-ampere S&C Circuit-Switchers that switch and protect 230-13.2-kv transformers, which are connected to a main/auxiliary split-bus arrangement with four outgoing circuit breakers. Each circuit breaker is connected to a lineup
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of S&C Metal-Enclosed Switchgear: two six-bay assemblies in the utility substation that also switch and protect circuits to the user’s installation; and the 32-bay and 33-bay assemblies highlighted in this photo sheet. For illustrative purposes, the two long lineups are shown In two rows, whereas at the installation these assemblies are placed in a single rowbut separated by a clear space of about 100 feet.
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Outdoor Distribution
13.8 kv – Power Operated
The interior view of a typical entrance bay is shown above. The main bus in the entrance bay (and in the next two adjacent bays on each side of it) Is rated for 1200 amperes continuous current and arranged for connection of three cables per phase.
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Pictured above is the interior view of a typical auxiliary bay. A 15-kva control power transformer rated 13.2-kv primary-
120-volt/240-volt secondary is mounted behind the meter panel and is not visible in the photo. This transformer provides power for low-voltage components in the lineup and 120-volt input to the battery charger. Key interlocks guard against access to high-voltage fuses on the control power transformer until its secondary load is disconnected. A screen behind the meter panel provides isolation for the control power transformer.
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Outdoor Distribution
13.8 kv - Power Operated
The Mini-Rupter Switch Illustrated above is typical of those that provide switching for up to 10 bays on each bus section of the two lineups. On this bay and the others like it, the manual switch operating handle is key interlocked to the door of the adjacent bay containing power fuses.
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The switchgear bay pictured above illustrates the interior of a typical enclosure containing only S&C Power Fuses-these bays provide protection on four of the six bus sections in the two lineups. In this bay, the screen is split, isolating the bus at the bottom of the enclosure. A horizontal steel barrier protects the bus from possible damage in the event fuses are inadvertently dropped during re-fusing. The enclosure door is key interlocked to the switch operating handle in the adjacent bay to guard against access to the fuses until the source-side interrupter switch is in the open position.
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Outdoor Distribution
13.8 kv – Power Operated
A typical power-operated feeder bay is pictured above. In addition to automatic trip-open operation in response to openphase conditions detected by S&C’s Open-Phase Detector, all feeder bays are equipped with switch operators that will also provide trip-open and trip-closed operation-initiated either locally by means of pushbuttons or remotely. Relays and associated wiring for remote Operation of the feeder bays are provided in each switchgear assembly. Switch operators, open-phase detectors, and relays are isolated from high voltage by interior barrier panels and from environmental conditions by gasketed, hinged covers.
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