Tips & News - Spring 2018

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Table 1. Bushing products offered by Hubbell

BUSHING APPLICATION MEDIUM

POC ®

PRC ®

SDC TM

Air - Oil Oil - Oil Air - Oil Air - Oil Air - Air Air - Air Air - H2

25kV - 500kV

15kV - 72.5 kV

15kV - 145kV 15kV - 145kV 15kV - 35kV 15kV - 145kV 15kV - 69kV 15kV - 145kV 15kV - 30kV 15kV - 145kV

Power Transformer

- -

GSU Transformer Oil Circuit Breaker

25kV

25kV - 230kV

15kV - 72.5 kV

Switchgear Wall / Floor

- - - - -

Generator

Air - Oil / Air - Air

Special Application

Varies

Selection process When it comes to selecting a bushing for a transformer or similar equipment, there are many factors and considerations involved in the choice of the type of bushing to use, and within the selection process, the type of bushing to use is not always obvious. Parameters such as voltage, current, strike distance, creep distance and CT pocket length are the usual selection criteria; however, consideration

PCORE is the only bushing manufacturer in the world to offer a 500 kV oil-filled, porcelain bushings certified to the IEEE-693 seismic standard

to this are the complexities revolving around choosing within the myriad of bushing technologies now available in the market, where there is a wide range and mix of traditional and new insulating technologies not limited to those summarized in Table 2, each providing its own set of features and benefits.

for transformer overloading conditions (both overload ratio and duration), temperature (ambient and temperature of the transformer), environment (enclosed or exposed), seismic requirements, angle of installation, and many other application specifics play a determining role in selecting the right bushing. Adding

Figure 2. The range of applications for each of the three bushing types offered by Hubbell

34.5

115

138

161

230

345

500

CURRENT

PRC

Quick- Link

SDC

POC

400A DL 600A DL 800A DL

1200A 2000A 3000A 4000A 5000A 6000A 7500A

10,000A 14,000A 18,500A 21,500A APPLICATIONS Transformer OCB GSU (high current)

Wall / Floor Switchgear Generator

SDC - Solid-Dielectric-Capacitor Type, cast epoxy composite bushing, capacitance graded, oil-free. PRC - Paper-Resin-Capacitor Type, resin-impregnated paper composite core bushing, capacitance graded, with upper porcelain insulator, available oil-filled and oil-free. POC - Paper-Oil-Capacitor Type, oil-impregnated paper core bushing, capacitance graded, with upper and lower porcelain insulators. QUICK-LINK - PRC or POC type, with the convenience of a draw-lead bushing and the current capability of a bottom-connected bushing.

20 | HUBBELL POWER SYSTEMS

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