The incoming compartment, where power is connected to the capacitor bank, is normally configured based on the availability of existing breakers, disconnect switches, and the rating of the capacitor bank. Typical configurations options are provided below.

ACCESSORIES FOR INCOMING COMPARTMENT

The following items are available for placement in the incoming compartment.

The capacitor compartment may consists of one capacitor bank or multiple capacitor stages. A capacitor bank or stage normally consists of the capacitors, capacitor fuses, and where applicable, a switching device and transient inrush reactors. Typical bank or stage configuration options are provided below. The capacitor bank/stage compartment is compartmentalized and isolated from the incoming compartment to allow for maintenance and repair.

The capacitor bank can be connected in a number of different ways depending upon bank rating and protection requirements. Typically, banks are provided with an ungrounded wye or ungrounded split-wye connection, but a grounded wye and Delta connection are also available.

Air Disconnect Switch
Externally operated chain-drive operated 3-pole air-disconnect switch to provide a "visible-break" and electrical isolation of the power capacitor bank during maintenance and repair.

Ground Switch
Externally operated chain-drive or direct-drive operated 3-pole ground switch to ground the load-side terminals of the incoming air-disconnect switch, breaker, and/or capacitors for safety during maintenance. The ground switch is key interlocked with the upstream disconnecting device to prevent closing of the ground switch onto a live bus.

Main Incoming Fuses
Main incoming current limiting fuses (with local and remote blown fuse indication) for short circuit protection of the power capacitor bank.

Main Incoming Breaker
Main incoming drawout or fixed-mounted circuit breaker for protection, isolation, and switching of the power capacitor bank.

Lightning Arresters
Lightning arresters are provided as standard on NEPSI's equipment to protect the power capacitor bank and incoming cables from lightning and switching transients.

Control Power Transformer(s) (CPT)
Control power transformers to supply control power and voltage sensing to the capacitor bank's, metering, protection, and control system.

Current Transformers (CT)
Current tranformers to supply a current signal for the capacitor bank's metering, protection, and control system.

Bus Duct Entry
Bus duct entry to allow for direct bus connection to switchgear.

Dead-Front Entry
Dead-front design entry that allows for 200 amp and 600 amp separable elbow connectors.

Roof Bushing Entry
Roof bushing entry to allow for direct connection to overhead bus within substations.

Capacitors
Low loss, double bushing capacitors that meet or exceed IEC 871, IEEE 18 and CSA standards. Capacitors are typically connected ungrounded-wye or ungrounded split-wye. Internal discharge resistors reduce the residual voltage to less than 50 volts within 5 minutes of de-energization. The dielectric fluid is environmentally friendly, biodegradable, non PCB, with low toxicity. Internally fused capacitors are available upon request.

Capacitor Fusing
Capacitors are individually fused with current limiting fuses. These fuses reduce the possibility of case rupter on capacitor failure and allow the power capacitor bank to continue to operate when a capacitor fails. The fuses are equipped with blown fuse indicators and can also be equipped with direct fuse operation sensors for blown fuse detection.

Capacitor Switches
Single stage and multi-stage power capacitor banks are equipped with vacuum contactors (for voltages less than 6.6kV), capacitor switches, or circuit breakers (fixed or drawout) for capacitor switching.

Transient Inrush Reactors
NEPSI's TI-Reactors™ are provided on multi-stage power capacitor banks to limit the frequency and magnitude of inrush currents associated with back-to-back capacitor bank switching. These reactors are required to prevent premature capacitor switch or breaker failure and are sized by NEPSI.

Current Transformers
Multi-stage capacitor banks can be equipped with stage current transformers to allow for metering and protection of individual stages.

Air Disconnect Switch
Externally operated, key interlocked, 3-pole air-disconnect switch(s) that isolates a single stage of a multi-stage capacitor bank, allowing for partial bank operation during maintenance.

Ground Switch
Externally operated, key interlocked, 3-pole ground switch(s) that grounds the capacitor terminals to ensure all trapped charge has been removed from the capacitors.

Automatic Capacitor Bank Controllers
Automatic Power Capacitor Banks are equipped with various types of controllers to automatically turn power capacitor banks (stages) on and off based on var flow, watt flow, voltage level, current-flow, time-of-day, or day-of-week. Controllers are integrated with the protection system and other components to form a fully integrated system.

Protection
Power Capacitor Banks can be equipped with various protection relays, meters, and sensors to protect the capacitor bank as well as the system from over-voltage, out-of-balance operation from capacitor failure, internal faults, and over-temperature due to fan failure. Protection devices are integrated with the control system and other components to form a fully integrated system.

Logic Controllers (PLC, Smart Relays)
Various logic controllers are available to provide auxiliary control functions such as timing, interlocking, blocking, and permissives. Controllers also provide a communication gateway between plant DCS systems and the power capacitor bank.

Arc Flash Mitigation
See NEPSI’s technical note on arc flash mitigation in metal-enclosed capacitor banks and harmonic filter banks. This technical note provides over 30 mitigation strategies available from NEPSI to minimize the level of exposure to arc flash events as well as ways to reduce the probability that an arc flash event will occur in the first place.

Enclosure
Free standing, compartmentalized, all welded, 11 gauge galvanneal steel construction with 3 point pad-lockable latching handles and stainless steel hinges. The enclosure is painted with Engineered Siloxane, a Marine paint with rated salt spray of 5500 hours. NEMA 3R (IP64) construction is standard, NEMA 12 (IP65) and 4X (IP66) are available as an option. Base of enclosure as well as capacitor supports are formed from C4 structural steel. Door stays and windows are standard.

Key Interlock System
As standard, a key interlock system is provided that dictates proper sequence of operation and safe entry into the enclosure. Upstream devices may be included in the interlock sequence.

Ground and Phase Bus
A 1/4" X 2" Tin plated ground bus (or Silver when specified) is provided through the width of the enclosure to assist in grounding during maintenance. All phase bus is rated at a minimum of 135% of the bank nominal current rating.