Siemens GM-SG

Instrument
Transformers
Current
Transformers
The toroidal
current
transformers
shown installed
in
a
unit
in
Figure
34
are
the
most
commonly
used
type
in
metal
-
clad
switchgear
equipment
.
The circuit breaker
primary
studs
pass
through
the
transformers
when
in
the
CONNECT
position
.
Types
MD
or
MDD
current
transformers
are
of
the
toroidal
type
mounted
in
the
circuit
breaker
compartment
behind the
shutter
barrier
.
Up
to
two
standard
or
one
high
accuracy
current
transformers
may
be mounted around each
primary
insulator tube
.
Figure
34
.
Type
MD
CT
'
s
Installed
on
Lower
Disconnects
.
(
CT
Barrier Removed
for
Photo
)
A
zero
sequence
toroidal
current
transformer
can
be
furnished for
ground
sensing
circuits
.
This
transformer
is mounted
in
the
primary
cable
area
at
a
convenient
height
for
receiving
purchaser
'
s
cables
.
Zero
sequence
current
transformers
may
require
that
conduits
for
multiple
bottom
entrance
cables be
recessed
.
See
Figure
25
.
37
Courtesy of NationalSwitchgear.com