GE TMC21B User manual

INSTRUCTIONS
GEK
-
49940
B
THERMAL
OVERCURRENT
RELAY
TYPES
TMC
21
B
TMC
23
B
GENERAL
ELECTRIC
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GEK
-
49940
TABLE
OF
CONTENTS
PAGE
DESCRIPTION
3
APPLICATION
3
RATINGS
5
HIGH
-
SEISMIC
INSTANTANEOUS
UNIT
5
HIGH
-
SEISMIC
TARGET
5
CONTACTS
6
BURDENS
6
THERMAL
UNIT
6
HIGH
-
SEISMIC
INSTANTANEOUS
UNIT
6
CHARACTERISTICS
7
THERMAL
UNIT
7
HIGH
-
SEISMIC
INSTANTANEOUS
UNIT
7
HIGH
-
SEISMIC
TARGET
7
CONSTRUCTION
7
RECEIVING
,
HANDLING
,
AND
STORAGE
ACCEPTANCE
TESTS
8
8
VISUAL
INSPECTION
.
.
.
.
TESTING
FACILITIES
.
.
.
POWER
REQUIREMENTS
,
GENERAL
THERMAL
UNIT
9
9
9
9
HIGH
-
SEISMIC
INSTANTANEOUS
UNIT
10
HIGH
-
SEISMIC
TARGET
10
INSTALLATION
11
PERIODIC
CHECKS
AND
ROUTINE
MAINTENANCE
11
CONTACT
CLEANING
11
SYSTEM
TEST
12
RENEWAL
PARTS
12
LIST
OF
FIGURES
13
COVER
(
8043501
)
2
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GEK
-
49940
THERMAL
OVERCURRENT
RELAY
TYPES
TMC
21
B AND
TMC
23
B
DESCRIPTION
The
TMC
21
B
and
TMC
23
B
are
single
-
phase
thermal
overcurrent
relays
designed
for
motor
protection
,
and
instantaneous
overcurrent
difference
between
the
two
types
of
relays
is
as
follows
:
They
provide
both
thermal
overload
short
circuit
protection
.
The
standard
time
curve
,
Figure
6
TMC
21
B
short
time
curve
,
Figure
7
TMC
23
B
Each
relay
consists
of
an
induction
thermal
unit with
ambient
temperature
compensation
,
a
universal
target
unit
,
and
an
instantaneous
overcurrent
unit with
an
independent
mechanical
target
.
The
thermal
and
the
instantaneous
unit
each have
one
normally
-
open
contact
.
instantaneous
-
unit
contact
is
self
reset
.
thermal
-
unit
contact
are
all
reset
by
the
same
reset
mechanism
,
is
described
in
detail
in
the
text
under
the
heading
of
CONSTRUCTION
.
The
relay
internal connections
are
shown
in
Figure
4
and
the
outline
and
panel
-
drilling
dimensions
are
shown
in
Figure
10
.
The
thermal
-
unit
contact
is
hand
reset
,
while
the
The
two
targets
and
the
This
APPLICATION
The
TMC
relays
described
here
are
designed
to
provide
thermal
-
overload and
short
-
circuit
protection
for
motors
.
The
relays
are
not
intended
for
use
directly
in
primary
motor
circuits
.
They
should
always
be
applied
with
current
transformers
(
CTs
)
so
that
they
will
be self
-
protecting
on
primary
short
circuits
.
The
CTs
will
saturate
before
excessive
secondary
currents
can
be
reached
.
The
relay
thermal
-
unit
rating
should be
selected
so
that
the
maximum
full
-
load
motor
current
on
a
secondary
basis
falls
between
the
minimum
and
maximum
values
of
current
shown
in
the
RELAY
SELECTION
TABLE
.
These
instructions
do
not
purport
to
cover
all
details
or
variations
in
equipment
nor
provide
for
every
possible
contingency
to
be
met
in
connection
with installation
,
operation
or
maintenance
.
Should
further
information
be desired
or
should
particular problems
arise
which
are
not
covered
sufficiently for
the
purchaser
'
s
purposes
,
the
matter
should be
referred
to
the
General
Electric
Company
.
To
the
extent
required
the
products
described herein
meet
applicable
ANSI
,
IEEE
and
NEMA
standards
;
but
no
such
assurance
is
given
with
respect
to
local codes and
ordinances because
they
vary
greatly
.
3
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GEK
-
49940
RELAY
SELECTION
TABLE
MOTOR
FULL
-
LOAD
CURRENT
,
AMPERES
CURRENT
RATING
,
AMPERES
MODEL
12
TMC
MIN
.
MAX
.
THERMAL
INST
.
21
B
23
B
UNIT
UNIT
FORM
FORM
1.32
1.45
1.64
6
-
150
1
1
1.46
1.82
1.59
6
-
150
2
2
1.60
1.75
2.00
6
-
150
3
3
1.76
1.93
6
-
150
2.20
4
4
1.94
2.11
2.42
6
-
150
5
5
2.12
6
-
150
2.33 2.65
6
6
6
-
150
2.34
2.55
2.92
7
7
2.81
2.56
3.20
6
-
150
8
8
2.82
3.09
3.52
6
-
150
9
9
3.10
3.39
6
-
150
3.87
10
10
3.40
3.74
6
-
150
11
11
4.25
4.11
6
-
150
3.75
4.68
12
12
4.12
5.15
6
-
150
4.47
13
13
4.48
6
-
150
4.97
5.60
14
14
The
maximum
full
-
load
motor
current
is
determined
as
the
nameplate
current
multiplied
by
the
correction
factor
given
in
the
following
table
,
depending
upon
the
type
of
motor
being
used
:
TEMPERATURE
RATING
OF
MOTOR
CORRECTION
FACTOR
Continuous
,
1.15
service
factor
Continuous
,
1.0
service
factor
Short
time
,
60
minutes
Short
time
,
30
minutes
Short
time
,
15
minutes
Short
time
,
5
minutes
1.0
0.9
0.8
0.75
0.7
0.6
The
thermal
-
unit
tripping
current
is
adjustable
over
the
range
of
The
relay
is
calibrated
at
coil
rating
current
with
a
-
10
%
+
0
%
90
%
to
110
%
of
the
nominal
coil
rating
.
40
°
C
to
just
trip
at
the
If
the
motor
full
-
load
current
(
with
correction
factor
applied
)
is
near
the
maximum
of
the
current
-
selection
range
for
the
chosen
relay
,
unnecessary
tripping
may
occur
because
of
the
negative
tolerance
for
the
calibration
current
.
tolerance
.
If
such
unnecessary
tripping
the
thermal
-
unit
tripping
current
should
be
increased
The
thermal
-
unit
should
occur
,
to
110
%
of
coil
rating
to
eliminate
the
problem
,
ambient
-
temperature
compensation
is
discussed
under
CHARACTERISTICS
.
4
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GEK
-
49940
The
external
connection
diagram
for
these
relays
is
shown
Figure
5
.
protection
,
in
A
minimum
of
two
relays
is
required
for
adequate
motor
as
is
shown
.
RATINGS
The
TMC
21
B
relay
is
rated for
50
/
60
hertz
.
The
ratings
of
thermal
and
instantaneous
units
are
shown
in
the
RELAY
SELECTION
TABLE
in
the
preceding
APPLICATION
section
.
The
TMC
23
B
relay
is
rated
for
60
hertz
.
HIGH
-
SEISMIC
INSTANTANEOUS
UNIT
The
instantaneous coil is
tapped
for
operation
on
either
one
of
Selection
of
the low
or
high
range
is
See
the
Table
I
lists
the
instantaneous unit
two
ranges
(
low
or
high
)
,
determined
by
the
connections
made
to
Terminals
8
and
8
A
.
internal
connections
,
Figure
4
.
ranges
,
rating
,
one
-
second
rating
,
etc
.
TABLE I
CONTINUOUS
RATING
(
AMPS
)
HIGH
-
SEISMIC
INSTANTANEOUS
UNIT
(
AMPS
)
ONE
ftt
SECOND
RATING
(
AMPS
)
ft
RANGE
(
AMPS
)
RANGE
K
10.2
6
-
30
LOW
67
,
000
6
-
150
260
19.6
30
-
150
HIGH
tt
The
range
is
approximate
,
which
means
that the
6
-
30
,
30
-
150
may
be
6
-
28
,
28
-
150
.
one
ampere
overlap
between
the
maximum
low
setting
and
the
minimum
high setting
.
higher
range
,
since
it
has the
higher
continuous
rating
.
There
will
always
be
at
least
Whenever
possible
select the
t
+
t
Higher
currents
may
be
applied
for
shorter
lengths
of
time
in
accordance
with
the
formula
:
VK
/
T
I
HIGH
-
SEISMIC
TARGET
Ratings
for
the
target
unit
are
shown
in
Table
II
.
If
the
tripping
current
exceeds
30
amperes
,
an
auxiliary
relay
should be used
,
the
connections
being
such that the
tripping
current
does
not
pass
through
the
target
coil
of
the
protective
relay
.
5
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GEK
-
49940
TABLE II
TAP
0.2
2.0
D
.
C
.
RESISTANCE
±
10
%
(
OHMS
)
8.0
0.24
MINIMUM
OPERATING
(
AMPERES
)
+
0
-
25
%
0.2
2.0
CARRY
CONTINUOUSLY
(
AMPERES
)
0.3
3.0
CARRY
30
AMPS FOR
(
SEC
.
)
0.03
4.0
CARRY
10
AMPS
FOR
(
SEC
.
)
0.25
30.0
60
HZ
IMPEDANCE
(
OHMS
)
68.0
0.73
CONTACTS
The
contacts
will
make
and
carry
30
amperes
trip
current
and
three
(
3
)
amperes
continuously
except
as
limited
in
the
target
circuit
noted
in
Table
II
.
BURDENS
THERMAL
UNIT
The
burden
of
the
TMC
21
B
at
rated
current
is
approximately
13.5
volt
-
amperes
and
12
watts
for
60
hertz
operation
or
approximately
12.5
volt
-
amperes
and
11
watts
for
50
hertz
operation
,
the
TMC
23
B
is
approximately
10
%
higher
than the
TMC
21
B
type
relay
.
The
burden
of
The
volt
-
ampere
burden
of
the
TMC
21
B
at
five
amperes
is
approximately
equal
to
K
divided
by
the
square
of
the
current
rating
,
where
K
is
325
for
60
hertz and
305
for
50
hertz
.
The volt
-
ampere
burden
of
the
TMC
23
B
at
five
amperes
is
approximately
equal
to
K
divided
by
the
square
of
the
current
rating
where
K
is
295
.
HIGH
-
SEISMIC
INSTANTANEOUS
UNIT
The
High
-
Seismic
instantaneous
unit
burdens
are
listed
in
Table
III
.
TABLE
III
HIGH
SEISMIC
HZ
RANGE
INST
.
UNIT
(
AMPS
)
BURDENS
AT
MIN
.
PICKUP
(
OHMS
)
BURDENS
IN
OHMS
(
Z
)
TIMES PICKUP
MIN
.
RANGE
(
AMPS
)
PICKUP
(
AMPS
)
R
Jx
z
10
20
3
LOW
6
-
30 6
30
-
150
30
0.110
0.078
0.135
0.022
0.005
0.023
0.095
0.081
0.079
0.022 0.022
0.022
6
-
150
60
HIGH
LOW
6
-
30
6
30
-
150
30
0.092
0.065
0.112
0.018
0.004
0.019
0.079
0.068
-
0.066
0.018 0.018
0.018
6
-
150
50
HIGH
6
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GEK
-
49940
CHARACTERISTICS
THERMAL
UNIT
The
thermal
unit
consists
of
a
current
coil
placed
over
a
bi
-
metal
helix
that
acts
as
the
short
-
circuited
secondary
of
a
transformer
.
The
current
heats
the
helix
,
causing
it
to
rotate
in
a
direction
to
close
the
hand
-
reset
contacts
.
Tripping
current
is
adjustable
from
90
%
to
110
%
of
coil
rating
.
The
contacts
cannot
be
reset
until
the
unit
has
cooled
for
a
time
.
The
relay
is
calibrated
at
40
°
C
and
has
built
-
in
compensation
for
changes
in
ambient
temperature
;
the
compensation
is
not
perfect
.
There
is
a
2
%
variation
in
trip
point
per
10
°
C
change
in
temperature
from
the
40
°
C
calibration
temperature
.
The
trip
point
will
decrease
as
the
ambient
temperature
increases
.
The
resulting
time
of
the
TMC
relays
should
be
with
±
25
%
of
the
time
-
current
characteristic
curve
as
shown
in
Figure
6
for
the
TMC
21
B
and
in
Figure
7
for
the
TMC
23
B
.
HIGH
-
SEISMIC
INSTANTANEOUS
UNIT
The
instantaneous
unit
has
a
25
-
to
-
l
range
with
a
tapped
coil
.
There
are
high
and
low
ranges
,
selected
by
means
of
interchanging
two
leads
on
the
case
block
.
See
the
internal
in
Figure
4
.
The
time
-
current
-
characteristic
curve
for
the
instantaneous
unit
is
shown
in
Figure
9
.
HIGH
-
SEISMIC
TARGET
The
target
has
an
operating
coil
tapped
at
0.2
and
2.0
amperes
.
The
relay
is
shipped
from
the
factory
with
the
tap
screw
in
the
higher
ampere
position
.
CONSTRUCTION
The
relay
case
is
suitable
for
either
surface
or
semiflush
panel
mounting
and
an
assortment
of
hardware
is
provided
for
either
mounting
.
The
cover
attaches
to
the
case
and
also
carries
the
reset
mechanism
.
screw
connections
at
the
bottom
only
for
The
electrical
connections
between
the
The
case
has
studs
or
the
external
connections
,
relay
units
and
the
case
studs
are
made
through
spring
-
backed
contact
fingers
mounted
in
stationary
molded
inner
and
outer
blocks
,
between
which
nests
a
removable
connecting
plug
that
completes
the
circuits
.
The
outer
block
,
attached
to
the
case
,
has
the
studs
for
the
external
connections
,
and
the
inner
block
has
the
terminals
for
the
internal
connections
.
The
relay
mechanism
is
mounted
in
a
steel
framework
called
the
cradle
and
is
a
complete
unit
,
with
all
leads
being
terminated
at
the
inner
block
.
This
terminal
is
held
firmly
in
the
case
with
a
latch
at
the
top
and
the
bottom
and
by
a
guide
pin
at
the
back
of
the
case
.
The
case
and
cradle
are
so
constructed
that
the
relay
cannot
be
7
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GEK
-
49940
inserted
in
the
case
upside
down
,
making
the
electrical
connections
between
the
respective
blocks
of
the
cradle
and
case
,
also
locks
the
latch
in
place
,
is
fastened
to
the
case
by
thumbscrews
,
holds
the
connecting
plug
in
place
.
The
connecting
plug
,
besides
The
cover
,
which
To
draw
out
the
relay
unit
,
the
cover
is
first
removed
,
and
the
Shorting
bars
are
provided
in
the
case
to
short
the
The
latches
are
then
released
,
and
the
To
replace
the
relay
unit
,
the
plug
drawn
out
.
current
transformer
circuits
.
relay
unit
can
be
easily
drawn
out
.
reverse
order
is
followed
.
A
separate
testing
plug
can
be
inserted
in
place
of
the
connecting
plug
to
test
the
relay
in
place
on
the
panel
either
from
its
own
source
of
current
,
or
from
other
sources
.
Or
,
the
relay
unit
can
be
drawn
out
and
replaced
by
another
that
has
been
tested
in
the
laboratory
.
The
target
is
mounted
on
the
front
top
left
,
and
consists
of
a
small
hinged
-
type
unit
that
raises
a
target
when
picked
up
.
target
is
released
by
raising
a
rod
located
at
the
lower
left
corner
of
the
relay
cover
.
The
In
addition
to
the
target
there
is
a
hinged
-
type
instantaneous
unit
mounted
on
the
front
top
right
,
picks
up
it
raises
a
target
that
latches
up
and
remains
exposed
until
The
same
reset
rod
that
releases
the
left
target
also
releases
the
instantaneous
unit
target
.
When
the
instantaneous
unit
it
is
released
.
RECEIVING
,
HANDLING
,
AND
STORAGE
These
relays
,
when
not
included
as
a
part
of
a
control
panel
,
will
be
shipped
in
cartons
designed
to
protect
them
against
damage
.
Immediately
upon
receipt
of
a
relay
,
examine
it
for
any
damage
sustained
in
transit
,
handling
is
evident
,
transportation
company
Electric
Sales
Office
.
If
injury
or
damage
resulting
from
rough
a
damage
claim
at
once
with
the
nearest
General
file
and
promptly
notify
the
Reasonable
care
should
be
exercised
in
unpacking
the
relay
in
order
that
none
of
the
parts
are
injured
nor
the
adjustments
disturbed
.
If
the
relays
are
not
to
be
installed
immediately
,
they
should
be
stored
in
their
original
cartons
in
a
place
that
is
free
from
moisture
,
dust
,
and
metallic
chips
.
outside
of
the
case
may
find
its
way
inside
when
the
cover
and
cause
trouble
in
the
operation
of
the
relay
.
Foreign
matter
collected
on
the
is
removed
ACCEPTANCE
TESTS
Immediately
upon
receipt
of
the
relay
an
inspection
and
acceptance
test
should
be
made
to
make
sure
that
no
damage
has
been
sustained
in
shipment
and
that
the
relay
calibrations
have
not
been
8
Courtesy of NationalSwitchgear.com

GEK
-
49940
If
the
examination
or
test
indicates
that
readjustment
is
refer
to
the
section
on
SERVICING
.
disturbed
.
necessary
,
These
tests
may
be
performed
as
part
of
the
installation
or
of
the
acceptance
tests
,
at
the
discretion
of
the
user
.
Since
most
operating
companies
use
different
procedures
for
acceptance
and
for
installation
tests
,
the
following
section
includes
all
applicable
tests
that
may
be
performed
on
these
relays
.
VISUAL
INSPECTION
Check
the
nameplate
to
make
sure
that
the
model
number
and
rating
of
the
relay
agree
with
the
requisition
.
Remove
the
relay
from
its
case
and
check
that
there
are
no
broken
or
cracked
parts
or
any
other
signs
of
physical
damage
.
TESTING
FACILITIES
All
General
Electric
drawout
-
case
relays
may
easily
be
tested
in
the
case
by
using
either
the
XLA
12
A
or
XLA
13
A
test
plugs
,
has
20
fingers
,
which
bring
both
the
ten
relay
connections
and
the
ten
outside
-
world
connections
to
the
front
of
the
relay
for
easy
access
.
to
the
front
of
the
relay
,
without
disturbing
the
CT
shorting
bars
.
The
XLA
12
A
The
XLA
13
A
test
plug
brings
only
the
ten
relay
connections
For
further
information
on
these
test
plugs
,
refer
to
Section
7332
in
the
General
Electric
Apparatus
Handbook
or
contact
the
nearest
General
Electric
Sales
Office
.
POWER
REQUIREMENTS
,
GENERAL
All
devices
operating
on
alternating
current
(
AC
)
are
affected
by
Since
non
-
sinusoidal
waveforms
can
be
analyzed
as
a
frequency
.
fundamental
frequency
plus
harmonics
of
that
fundamental
frequency
,
it
follows
that
alternating
-
current
devices
(
relays
)
will
be
affected
by
applied
waveforms
.
significantly
affected
by
the
application
of
waveforms
.
AC
relays
(
and
AC
devices
in
general
)
are
non
-
sinusoidal
Therefore
,
in
order
to
test
AC
relays
properly
it
is
essential
to
use
a
test
voltage
and
/
or
current
waveform
that
is
sinusoidal
,
purity
of
the
sine
wave
(
i
.
e
.
,
its
freedom
from
harmonics
)
cannot
be
expressed
as
a
finite
number
for
any
particular
relay
;
however
,
any
relay
using
tuned
circuits
,
RL
or
RC
networks
,
or
saturating
electromagnets
(
such
as
time
-
overcurrent
relays
)
would
be
especially
affected
by
non
-
sinusoidal
wave
forms
.
The
THERMAL
UNIT
it
is
advisable
not
The
relay
has
been
adjusted
at
the
factory
;
to
disturb
the
adjustments
,
helix
and
the
compensating
bi
-
metal
should
never
be
tampered
with
at
any
time
.
It
is
most
important
that
the
bi
-
metal
9
Courtesy of NationalSwitchgear.com

GEK
-
49940
Upon
leaving
the
factory
,
the
relay
is
set
for
the
100
%
If
it
is
desired
to
adjust
the
relay
to
trip
at
a
slightly
higher
or
lower
value
of
current
,
loosen
the
adjustment
-
locking
screw
(
see
Figure
3
)
.
Then
the
adjusting
screw
can
be
turned
to
provide
the
desired
adjustment
,
adjustment
-
locking
screw
.
calibration
.
Be
sure
to
tighten
the
Tests
on
the
thermal
unit
should
be
made
with
the
cover
on
.
In
order
to
prevent
some
pre
-
heating
of
the
unit
(
such
as
would
occur
while
adjusting
the
current
in
the
test
circuit
to
the
desired
level
with
the
thermal
unit
in
the
circuit
)
,
bypass
,
rather
than
shorting
out
,
the
thermal
unit
during
the
current
setting
.
When
the
thermal
unit
is
included
in
the
circuit
,
the
magnitude
of
current
will
be
somewhat
less
,
but
its
value
can
be
determined
during
the
timing
period
to
check
the
level
of
percentage
overload
.
The
resulting
time
should
be
within
±
25
%
of
the
published
time
curves
.
HIGH
-
SEISMIC
INSTANTANEOUS
UNIT
Make
sure
that
the
instantaneous
unit
is
wired
for
the
range
in
See
Figure
4
.
range
which
it
is
to
operate
,
higher
range
,
since
the
higher
rating
.
Whenever
possible
use
the
has
the
higher
continuous
The
instantaneous
unit
has
an
adjustable
core
located
at
the
top
of
the
unit
,
as
shown
in
Figure
1
.
To
set
the
instantaneous
unit
to
a
desired
pickup
,
loosen
the
locknut
and
adjust
the
core
,
the
core
clockwise
decreases
the
counterclockwise
increases
the
pickup
,
until
the
operation
,
desired
pickup
value
is
reached
,
Turning
pickup
;
turning
the
core
Bring
up
the
current
slowly
It
may
be
necessary
to
repeat
this
Once
the
unit
picks
up
.
until
the
desired
pickup
value
is
obtained
.
tighten
the
locknut
.
CAUTION
Refer
to
Table
I
for
the
continuous
and
one
-
second
ratings
of
the
instantaneous
unit
.
applying
current
to
the
instantaneous
unit
.
Do
not
exceed
these
ratings
when
The
range
of
the
instantaneous
unit
must
be
obtained
between
a
core
position
of
1
/
8
of
a
turn
of
full
-
clockwise
and
20
turns
counterclockwise
from
the
full
-
clockwise
position
.
HIGH
-
SEISMIC
TARGET
The
pickup
and
dropout
current
is
listed
in
Table
IV
.
TABLE
IV
PICK
-
UP
CURRENT
DROPOUT
CURRENT
TAP
0.2
0.12
-
0.19
1.2
-
1.9
0.05
OR
MORE
0.50
OR
MORE
2.0
10
Courtesy of NationalSwitchgear.com

GEK
-
49940
INSTALLATION
The
relay
should
be
installed
in
a
clean
,
dry
location
,
free
from
dust
,
and
well
lighted
to
facilitate
inspection
and
testing
.
The
relay
should
be
mounted
on
a
vertical
surface
,
and
panel
drilling
is
shown
in
Figure
10
.
The
outline
internal
-
connections
diagram
for
the
relays
is
shown
in
Typical
external
connections
are
shown
in
Figure
5
.
The
Figure
4
.
PERIODIC
CHECKS
AND
ROUTINE
MAINTENANCE
In
view
of
the
vital
role
of
protective
relays
in
the
operation
of
a
power
system
,
it
is
important
that
a
periodic
test
program
be
followed
.
It
is
recognized
that
the
interval
between
periodic
checks
will
vary
depending
upon
environment
,
type
of
relay
and
the
user
'
s
experience
with
periodic
testing
.
Until
the
user
has
accumulated
enough
experience
to
select
the
test
interval
best
suited
to
his
individual
requirements
it
is
suggested
that
the
points
listed
below
be
checked
at
an
interval
of
from
one
to
two
years
.
To
substitute
a
new
current
coil
in
the
thermal
unit
,
the
procedure
should
be
as
follows
:
Remove
the
coil
leads
from
Terminals
5
and
6
.
1
.
Loosen
the
three
mounting
screws
and
remove
the
retaining
plate
(
see
Figure
2
)
.
2
.
Lift
out
the
present
coil
and
substitute
the
replacement
for
it
,
taking
care
that
the
coil
is
mounted
with
the
two
locating
pins
on
the
lower
side
.
3
.
Replace
the
retaining
plate
so
that
it
rests
squarely
against
the
end
of
the
core
.
4
.
Tighten
the
three
mounting
screws
.
5
.
Connect
the
coil
leads
to
Terminals
5
and
6
.
6
.
CONTACT
CLEANING
For
cleaning
relay
contacts
,
a
flexible
burnishing
tool
should
be
This
consists
of
a
flexible
strip
of
metal
with
an
etch
-
The
used
.
roughened
surface
resembling
in
effect
a
superfine
file
,
polishing
action
is
so
delicate
that
no
scratches
are
left
,
yet
it
will
clean
off
any
corrosion
thoroughly
and
rapidly
.
Its
flexibility
ensures
the
cleaning
of
the
actual
points
of
contact
,
knives
,
files
,
abrasive
paper
or
cloth
of
any
kind
to
clean
relay
contacts
.
Do
not
use
11
Courtesy of NationalSwitchgear.com

GEK
-
49940
SYSTEM
TEST
Although
this instruction
book
is
primarily
written
to
check
and
set
the
TMC
relay
,
overall
functional
tests to
check
the
system
operation
are
recommended
at
intervals
based
on
the
customer
'
s
experience
.
RENEWAL
PARTS
It
is
recommended
that
sufficient
quantities
of
renewal
parts
be
carried
in
stock
to
enable
the
prompt
replacement
of
any
that
are
worn
,
broken
or
damaged
.
When
ordering
renewal
parts
,
address
the
nearest
Sales
Office
of
the
General
Electric
Company
,
specify
the
quantity
required
,
the
name
of
the
part
wanted
,
and
the
complete
model number of
the
relay
for
which
the
part
is
required
.
12
Courtesy of NationalSwitchgear.com

GEK
-
49940
LIST
OF
FIGURES
PAGE
FIGURE
14
TMC
21
B
Relay
,
Front
View
1
15
TMC
21
B
Relay
,
Rear
View
2
Thermal
Unit with
Current
Coil
and
Reset
Rod
Removed
3
16
Internal
Connections
for
Type
TMC
21
B
and
TMC
23
B
Relays
17
4
Typical
External
Connections
for
Type
TMC
Relay
18
5
Time
/
Current
Characteristic
Curve
for
Type
-
TMC
21
B
Relay
*
6
19
Time
/
Current
Characteristic
Curve
for
Type
-
TMC
23
B
Relay
7
20
Transient
Overreach
Characteristics
of
the
High
-
Seismic
Instantaneous
Unit
. . . .
8
21
Time
/
Current
Characteristics
of
the
High
-
Seismic
Instantaneous
Unit
9
2 2
Outline
and
Panel
Drilling
for
Types
TMC
21
B
and
TMC
23
B
Relays
*
10
23
^
Revised
since
last
issue
13
Courtesy of NationalSwitchgear.com

GEK
-
49940
ADJUSTABLE
POLE
PIECE
TARGET
NSTANTANEOUS
UNIT
TARGET
SEAL
-
1
N
UNIT
RESET
Figure
1
(
8043502
)
TMC
21
B
Relay
,
Front
View
14
Courtesy of NationalSwitchgear.com

GEK
-
49940
INSTANTANEOUS
UNIT
ADJUSTABLE
POLE
PIECE
RESET
ROD
(
8043503
)
TMC
21
B
Relay
,
Rear
View
Figure
2
15
Courtesy of NationalSwitchgear.com

GEK
-
49940
MOUNTING
SCREWS
FOR
RETAINING
PLATE
s
.
.
mmmmm
A
M
i
h
SCALE
PLATE
ADJUSTABLE
POLE
PIECE
&
£
TARGET
_ _
-
TARGET
SEAL
-
IN
UNIT
INSTANTANEOUS
UNIT
RESET
LEVER
OPERATING
GO
IL
COMPENSATING
BIMETAL
-
ADJUSTMENT
LOCKING
SCREW
RESET
ROD
-
ADJUSTING
SCREW
STATIONARY
CONTACT
MOVABLE
CONTACT
BRUSH
Figure
3
(
8007955
)
Thermal
Unit
with
Current
Coil
and
Reset
Rod
Removed
16
Courtesy of NationalSwitchgear.com

GEK
-
49940
UNIT
!
/
t
INST
INST
UNIT
UNIT
i
E
T
E
I
I
!
8
A
ra
l
\
/
*
V
*
v
*
v
#
y
Y
V
Y
Y
V
"
TvJ
INSTANTANEOUS
SETTINGS
:
o
o
o
o
SHOWN
IN
LOW
RANGE
.
CONNECT
"
E
^
TO
8
A
AND
*
T
*
TO
8
FOR
THE
HIGH
RANGE
.
5
3
7
o
o
o
o
8
6
2
4
^
=
SHC
-
RT
FINGER
Internal
Connections
for
Type
TMC
21
B
and
TMC
23
B
Relays
Figure
4
(
0273
A
9556
)
17
Courtesy of NationalSwitchgear.com

GEK
-
49940
A
-
C
BUS
TRIP
BUS
(
O
2
3
i
3
1
49
T
OTHER
49
RELAYS
2
I
t
52
52
a
52
o
o
Tt
5
r
-
9
t
(
-
)
450
7
LEGEND
49
THERMAL
UNIT
50
INSTANTANEOUS
UNIT
T
TARGET
52
CIRCUIT
BREAKER
TC
TRIP
COIL
a
AUXILIARY
CONTACT
,
CLOSED
WHEN
BREAKER
IS
CLOSED
.
MOTOR
Figure
5
(
0275
A
4381
)
Typical
External
Connections
for
Type
-
TMC
Relay
18
Courtesy of NationalSwitchgear.com

GEK
-
49940
T
T
T
9
t
I
i
i
1
I
f
i
1
I
I
i
4
-
4
i
,
2
L
°
.
i
.
"
5
if
)
J
<
3
h
-
“
>
u
:
-
z
Q
.
^ ^
^
LU
ro
ro
<
r
I
I
4
-
1
CO
CD
LU
^
_
00
c
\
j
-
J
<
3
ao
ao
o
.
z
>
mc
\
j
>
0
or
i
!
o
l
OJ
O
1
*
o
'
[
:
9
°
0
i
I
O
4
UJ
00
OO
5
CD
NT
f
b
!
5
.
'
t
—
-
?
-
.
.
i
r
i
1
a
-
<
1
T
cr
-
i
t
i
-
-
o
o
H
r
-
?
O
rx
7
9
CO
*
•
z
X
1
Q
3
<
X
:
2
XI
o
\
o
LU
:
in
1
:
•
r
t
t
1
T
I
1
—
'
I
*
"
1
I
- -
f
I
r
1
O
*
.
1
.
i
\
i
i
.
I
;
1
!
1
:
i
r
1
?
O
o
o
o
o
o
o
o
o
o
o
o
CO
C \
J
in
sr
u
>
S
3
b
3
<
MV
1100
031
Vd
!
N
30
d
3
d
(
0285
A
8975
)
Time
/
Current
Characteristic
Curve
for
Type
-
TMC
21
B
Relay
^
Figure
6
*
Revised since
last
issue
19
Courtesy of NationalSwitchgear.com

GEK
-
49940
o
s
8
8
§
8
8
8
O
o
CO
Q
_
8
W
P
o
^
8
g
O
o
OA
w
o
Os
]
o
CD
00
CO
-
LO
o
o
o
o
o
o
o
o
o
o
o
o
o o
o
o
oo
CO
UO
o
\
OvJ
T
-
i
S
3
d
3
dW
1103
031
Vd
iN
30
d
3
d
Figure
7
(
0418
A
0800
)
Time
/
Current
Characteristic
Curve
for
Type
-
TMC
23
B
Relay
20
Courtesy of NationalSwitchgear.com