Combined 34.5 kV Vacuum Circuit Breaker &

VDH/GSMIMechanically InterlockedGrounding Switch

U.S. Patent Pending

TM

VDH/GSMI Series

VDH/GSMI series is particularly suitable for application with wind farm collection circuits. This

model combines a main breaker with a high speed, mechanically-interlocked grounding switch

within the same outdoor enclosure, and totally replaces traditional use of grounding

transformers in wind generation installations.

Main breaker connects generator collection circuits to the transformer bus, while grounding switch

connects collection circuits automatically to ground, immediately after the main breaker opens.

The primary characteristic of the overall system is that the complete switching operation (time

duration for opening main breaker through closing grounding switch) is accomplished in less than

1 cycle (between 12 to 16 milliseconds).

When a conventional wind farm substation breaker opens and the wind turbines are still in operation

the voltage will rise on the 34.5 kV collection system cables between the turbines and the

substation. If the voltage is allowed to rise then the surge arresters at the substation and at the ends

of the 34.5 kV cable runs will be subjected to an overvoltage. The turbine controllers can also be

subjected to an overvoltage. It’s essential to keep the voltage down to the withstand limits of the

surge arresters and the turbine controllers.

Some wind generation installations traditionally use grounding transformers in order to limit that

voltage rising. But VDH/GSMI series provides a very fast switching time to ground which holds

transient voltage excursion to very low levels, thereby eliminating the need for grounding

transformers, with very important advantanges as follows:

*Eliminates need for grounding transformer for each collection circuit, resulting in elimination of:

first cost for expensive grounding transformers, grounding transformers installation labor costs and

grounding transformers installation materials costs.

*Eliminates grounding transformers core losses, which amounts to a very large savings over project life.

Enclosure is metal enclosed, self-supporting and free standing construction, with weatherproof

design suitable for installation in an unprotected environment, equipped inside with the following

main components:

*Three-pole main vacuum breaker combined with a high speed, mechanically-interlocked three-

pole vacuum grounding switch.

a spring

*Epoxy resin bushings including 4 hole flat pad stud connectors.

*Epoxy insulated ring-core current transformers installed around the bushings (up to two current

transformers per bushing)

*Frontal & rear low voltage compartments including control push-buttons, indicating lamps,

current transformers terminal blocks and auxiliary devices.

All exterior parts fabricated from steel sheet with cataphoresis protection as anticorrosive process

which provides longlasting perfomance in corrosive or contaminated environments. Roof assembly

particularly fabricated in aluminium to prevent eddy currents around bushings.

Manufactured and tested to meet ANSI C37 and IEC 62271-100 standards, this series provides easy

installation and accessibility, minimal maintenance and long service life.

*Commutation & oper ting mechanism, stored energy type.

Combined Vacuum Circuit Breaker & Grounding SwitchMechanically Interlocked

TM

TM

TM

VDH/GSMI SeriesElectrical Ratings

Dimensions and Weights

Ra

ted

Vo

lta

ge

-

Ra

ted

Co

ntin

uo

us

Cu

rre

nt

630/2000

A

Ma

kin

g C

ap

ab

ility

(pe

ak

va

lue

)

65

32.5

kA

Die

lec

tric

Str

en

gth

Imp

uls

e F

ull

Wa

ve

(BIL

)

200

kV

Rate

d O

pe

ning

Tim

e

mseg

Rate

d C

losin

g T

ime

mseg

Rate

d A

rcin

g T

ime

mseg

Sho

rt T

ime

With

sta

nd

Cu

rre

nt

25

12.5

kA (3 sec)

Die

lec

tric

Str

en

gth

With

sta

nd

60

Hz

1 m

in

80

kV mseg

Rate

d M

ec

hani

ca

lC

om

mut

atio

n Tim

e

Sym

me

tric

al I

nte

rrup

ting

Ca

pa

bilit

y

25

kA

-

70.9 inches1800 mm

14

7.6

inc

he

s3

75

0 m

m

70.9 inches1800 mm

5 6

7 7

8

8 1 3

2

4

10 11

9

Approximate weight: 4070 pounds / 1850 kg

7 CURRENT TRANSFORMERS

MAIN BUSBARS

GROUNDING BAR

COMPARTMENT

CONTROL PUSH-BUTTONS INDICATING LAMPS

AUXILIARY & TERMINAL BLOCKS

&

8

9

1 MAIN VACUUM BREAKER

VACUUM GROUNDING SWITCH

OPERATING MECHANISM

MECHANICAL INTERLOCK

BUSHINGS (WIND FARM SIDE)

BUSHINGS (TRANSFORMER SIDE)

& COMMUTATION

2

3

4 10

5

6

11

Ra

ted

Ma

xim

um

Vo

lta

ge

38

kV

34.5

kV

groundingswitch

mainbreaker

Rate

d F

rec

uenc

y

60

Hz

3030 4 to 11

12 to 16

- - -

TM

VDH/GSMI SeriesTM

Ema Electromecánica S.A. - Av. San Martín 4970 (B1604CDX) Florida - Buenos Aires - Argentina - Phone: (54 11) 4760-0051 - Fax: (54 11) 4761-0646E-mail: gcom@ema-sa.com.ar - Website: www.ema-sa.com.ar

Due to the continuous development of standars as well as materials, the characteristics and dimensions indicated in this catalogue should be considered as binding only on confirmation from EMA.

© Ema Electromecánica S.A. 2007. All rights reserved.

1012

E 1

0/20

07 D

V

REPRESENTATIVE

The Main Breaker & Grounding Switch Unit

Commutation Oscillogram

C h a n n e l 1 i s t h e a n a l o g i c a l

representation of the main breaker

contact traveling, while channel 2 is

the logical representation of the

contacts posi t ion of both main

b reaker and g round ing sw i tch,

connected in a parallel circuit.

This real oscil logram shows that

complete switching sequence (time

duration for opening main breaker

through closing grounding switch) was

accomplished in 14.76 msec, and the

main breaker contact traveled more

than 75% of its total stroke when the

grounding switch closed.

main breakeropening grounding

switch closing

main breaker contact traveling

channel 1

channel 2

FRONTAL VIEW SIDE VIEW REAR VIEW

Main breaker (upper vacuum interrupters) connects generator collection circuits to the transformer bus, while high

speed, mechanically-interlocked grounding switch (lower vacuum interrupters) connects collection circuits

automatically to ground, with a complete switching sequence lower than 1 cycle (between 12 to 16 msec). The

transient voltage doesn’t rise enough in 1 cycle to be above the withstand of the arresters or the allowable rise at the

wind turbine controllers.

VDH/GSMI SeriesTM

VDH/GSMI SeriesTM