Dummy Removable Element, Type Pvd; Ground And Test Device - GE POWER/VAC 4.16 Instructions Manual

The fuses are mounted on a movable carriage equipped
with primary and secondary disconnecting devices
.
Single
phase control power transformers of 15 kVA and smaller and
their secondary breaker are mounted on the carriage with
the
fuses
.
See Fig
. 15
.
Larger control power transformers
,
up to 37.5 kVA single
phase
or 45 kVA 3 phase , are located in
the cable compartment
behind their associated fuse carriage
and their secondary breaker
is located behind a hinged cover
on the upper cable
compartment
.
When the
fuses are disconnected , they
are
at
a safe strik
-
ing
distance from all live parts of the switchgear
.
In addition
a grounding
device is
provided
which contacts the fuses
after
they
are
disconnected , effectively
removing any
static
charge
from the fuses
.
In this
position the
fuses
may be safely re
-
moved and replaced
.
The disconnecting devices are capable
of interrupting transformer
magnetizing
current
,
but should
not be used to interrupt load current
.
Mechanical or key
interlocks are applied to prevent operating the disconnect
-
ing device while the load is connected
.
This is generally
ac
-
complished
by interlocking
so that the transformer secon
-
dary breaker must be locked in the open position before the
disconnecting
device can be connected or disconnected
.
Current
-
limiting fuse and
control power transformer roll
-
outs
are
located
in auxiliary units
.
The key
for
the dummy element
interlock
will usually be
obtained from a transfer lock
at
which all the source keys are
accumulated and captured
before
the dummy element key
can be obtained
.
<
GROUND AND TEST DEVICE
This
device is
designed to make either the upper or
lower
primary conductors in the breaker unit readily accessible
.
The type PVV manual ground
and test device , provides a
convenient means of grounding the cables or the bus
in
order to safeguard personnel who may be working on
the
cables or the
equipment
.
The device can be used for apply
-
ing power for high
-
potential tests or for fault location
.
It
can
be used to
measure insulation resistance ( megger )
.
By
using voltage
transformers , it can also
be used
for phasing
out cables
.
Refer to the instruction book provided for this
device
.
If " hotsticks
" are used ,
they
should be insulated
.
See
GEK 39686 .
CAUTION
—
NOTE THAT THE MAIN SWITCH
-
GEAR BUS IS CONNECTED TO THE LOWER STUDS
WHEN THE DEVICE IS INSTALLED IN AN UPPER
COMPARTMENT
AND TO THE UPPER STUDS
WHEN THE DEVICE IS INSTALLED IN A LOWER
COMPARTMENT
.
Refer to Fig
.
9 , which shows a side
section view of the switchgear
,
for
clarification
.
DUMMY
REMOVABLE
ELEMENT
,
TYPE PVD
(
GEK 39678
)
#
In addition
to the
device described above , there is avail
-
able the deluxe power
-
operated type GMV device which has
a self
-
contained bus or line selector switch and a separately
controlled , power operated , three
-
phase grounding switch
.
The GMV device is
a
dead
-
front design with mechanical and
electrical interlocks
, provision for
remote control and plug
-
type cable testing and phasing
.
The primary conductors re
-
quired
for grounding are self
-
contained
,
with no
external
cable connections required
.
The
GMV device is designed for maximum safety
to
personnel
while accomplishing
all the
basic required
grounding and testing functions
.
Refer to the instruction
book GEK 39684 for more details
.
Dummy removable elements are
used
as
a
means
of
isolating circuits
or
bus
sections
where operation is in
-
frequent and
a
circuit breaker cannot be economically ) usti
-
fied
.
The device
consists of
a
circuit breaker mechanism
frame
and primary insulator supports
with six
primary
studs including disconnecting devices
.
Copper rods
are
bolted in the location
normally occupied by vacuum inter
-
rupters
.
The stationary structure
is
the
same as
for
a circuit
breaker
.
When the device is fully racked in , it
connects the
top set of metal
-
clad primary disconnects to the bottom set
.
An interlock system ,
consisting of a side extension identi
-
cal to the positive
interlock extension of a standard circuit
breaker when the
breaker is closed
,
insures that the dummy
element cannot be
racked in or
out unless all
sources
to
which it may connect
are
de
-
e nergized
.
A key lock is
provided on the dummy element
.
It takes
a
key
which becomes available only when all
sources to
which
the dummy might connect are de
-
energized
.
When
the
key
is available
,
the
key interlock can be operated to withdraw
the positive interlock extension
.
The dummy element
now
looks like
an open breaker ,
Mnd
it can be racked in or out
.
As long as the positive interlock extension is withdrawn , the
key
is captured and it cannot be released
unless the dummy
element is in the
CONNECTED or TEST position or com
-
pletely withdrawn
.
Hence , the sources to which the dummy
may connect cannot be re
-
energized until the dummy is in
one
of these three positions
.
20