GE IBCG51M*Y1A Series User manual

GEK-49822E
INSTRUCTIONS
GROUND
DIRECTIONAL
OVERCURRENT
RELAYS
TYPES
IBCG51M
IBCG51M(.-)Y1A
I BCG52M
IBCG53M
IBCG53M(—)Y1A
IBCG54M
IBCG77M
I
BCG78M
GE
Protection
and
Control
205
Great
Valley
Parkway
Malvern,
PA
19355-1337

GEK-4
9822
PAGE
DESCRIPTION
APPLICATION
RATINGS
TIME
OVERCURRENT UNIT
DIRECTIONAL UNIT
INSTANTANEOUS
UNIT
TARGET AND
SEAL-IN UNIT
CONTACTS
CHARACTERISTICS
PICKUP
RESET
(TIME OVERCURRENT
UNIT)...
OPERATING
TIME
BURDENS
CONSTRUCTION
DIRECTIONAL
UNIT
CONTACTS
TIME
OVERCURRENT
UNIT
TARGET SEAL-IN
UNIT
INSTANTANEOUS
UNIT
RECEIVING, HANDLING
AND
STORAGE
ACCEPTANCE
TESTS
VISUAL INSPECTION
MECHANICAL
INSPECTION
TOP
UNIT
(TOC)
BOTTOM UNIT (DIR)
TARGET
AND SEAL-IN UNIT!
INSTANTANEOUS
UNIT
13
DRAWOUT RELAYS,
GENERAL
14
POWER
REQUIREMENTS, GENERAL
14
TARGET
AND SEAL-IN UNIT
14
PICKUP
AND
DROPOUT
TEST
14
TIME
OVERCURRENT
UNIT
15
CURRENT
SETTING
15
TIME SETTING
16
PICKUP
TEST
16
TIME TEST
16
PAGE
3
DIRECTIONAL UNIT
17
4 CURRENT
POLARIZATION
17
5
POTENTIAL POLARIZATION
17
6 INSTANTANEOUS
UNIT
17
7
INSTALLATION
17
7
LOCATION
17
8
MOUNTING
18
8 CONNECTIONS
18
8
INSPECTION
18
8 CAUTION
18
9
OPERATION
18
9
TARGET AND SEAL-IN
UNIT
18
9
TIME OVERCURRENT
UNIT 18
11 DIRECTIONAL UNIT
19
11
CURRENT
POLARIZATION
19
11 POTENTIAL
POLARIZATION
19
11 INSTANTANEOUS
UNIT
ig
12 PERIODIC
CHECKS AND ROUTINE
12 MAINTENANCE
19
TARGET
AND
SEAL-IN UNIT
19
12
TIME OVERCURRENT
UNIT
19
13 DIRECTIONAL
UNIT
19
13 INSTANTANEOUS
UNIT
20
13 SERVICING
20
13 TARGET
AND
SEAL-IN
UNIT
20
13 TIME
OVERCURRENT
UNIT
20
DISK AND BEARINGS
20
CONTACT
ADJUSTMENT
20
CHARACTERISTICS
CHECK
AND
ADJUSTMENTS
20
DIRECTIONAL
UNIT
21
BEARINGS
21
CUP
AND STATOR
21
CONTACT ADJUSTMENTS
21
BIAS
TORQUE ADJUSTMENT
22
CLUTCH ADJUSTMENT
22
INSTANTANEOUS
UNIT
23
CONTACT
CLEANING
23
RENEWAL PARTS
23
CONTENTS
2

GEK—49822
GROUND
DIRECTIONAL
OVERCURRENT
RELAYS
TYPES
IBCG51M IBCG53M
IBCG77M
I
B
C
G 5
1
Fl
(
-
)
Y
1 A
I
BC
G
5
3M
(
-)
Y I A
I
BC 678
M
IBCG52M
IBCG54M
DESCRIPTION
The
Type
IBCG
relays
are
ground
directional
overcurrent
relays
used
primarily
for
the
protection
of
feeders
and
transmission
lines.
They
are available
with
either
inverse,
very
inverse
or
extremely
inverse
time
characteristics.
All
the
IBCG
relays
contain
a
time
overcurrent
unit
of
the
induction disk
type
and
an
instantaneous
directional
unit
of
the
induction
cup
type.
The directional
unit
can
be
potential polarized,
or
current
polarized,
or
both,
and
it
directionally
controls
the
operation
of
the
time
overcurrent
unit.
A
target
seal-in
unit
is
provided in
each
of
the
relays.
The
operating
coil
for
this
unit
is
connected
in
series
with
the
contacts
of
the
time
overcurrent
unit so
that
it
will
pick
up
whenever
the
time
overcurrent
unit operates.
The
contacts
of
the
seal-in
unit
are
connected
in
parallel
with
the
contacts
of
the
time
overcurrent
unit
to
provide
protection
for
them
and
their
associated
control springs.
Those
relays having
the
designation
Y1A
following
the
model
number
also contain
a
Hi—Seismic
instantaneous
overcurrent
unit
of the
hinged
armature
construction.
The
IBCG52M,
54M
and
the
78M
relay
models
are
the
two-contact
versions
of
the
IBCG51M,
53M
and
the
77M
relay
models
respectively.
All
the
IBCG
relays
are
mounted
in
standard
Ml
size
drawout
cases,
the
outline
and
panel
drilling
dimensions
for
which
are
given
in
Figure
26.
Internal connections
for
the
relays
are
given
in
Figure
5,
6,
7,
8
and
9.
Typical
external connections
are
shown by
Figures
10,
11
and
12.
Table
I
lists
the
various
models
and
ranges
that
are
available.
These
instructions
do
not
purport
to
cover
all
details or
variations
in
.quipaient
nor
to provide
for
every
possible
conttngency to
be
eet
In
connection with
installation,
operation or
,aint.nanc.. 5hould
further
infornation be
desired
or
should
particular problem
arise
which
are
not
covered
sufficxantly
for
the
purchaser’s
purposes, the
matter
should
be
referred
to
the
General
£I.ctrC Conça,29.
To
the
extent
required the
products described
herein
meet
applicable ANSI,
IEZ’E
and
RXNA
standards,
but
no
such
assurance
is
given
with
respect
to
local
codes
and
ordinances
because
they
vary
greatly.
3

GEK—49822
TABLE
I
EXTENDED
RANGE
IBCG
RELAYS
• Relay
Time
Inst
Pickup
Range
mt
Model
Characteristic
Unit
Inst.
Time
Conn.
IBCG51M(-)A
Inverse
No
-
0.5-4,
2-16
Fig. 5
I IBCG52M(-)A
Inverse
No
-
0.5—4,
2-16
Fig.
7
II3CG51M(-)Y1A
Inverse
Yes
6-150
0.5—4,
2-16
Fig. 6
IBCG53M(-)A
Very
Inverse
No
-
0.5-4,
1.5-12 Fig.
5
IBCG54M(-)A
Very
Inverse
No
-
0.5-4,
1.5-12
Fig. 7
IBCG53M(—)Y1A
Very
Inverse
Yes
6-150 0.5-4,
1.5-12
Fig. 6
IBCG77M(-)A
Extremely
Inverse
No
- 0.5-4,
1.5-12
Fig.
8
IBCG78M(—)A
Extremely
Inverse
No
—
0.5—4,
1.5—12
Fig.
9
APPLICATION
The
Type
IBCG relays
are
ground
directional
overcurrent
relays
that
may
be
used
as
ground
fault
detectors
in
a transmission
line
protective
relaying
scheme.
The
relays
contain
a
time
overcurrent
unit
that
is
torque
controlled
by
an
instantaneous
directional
overcurrent
unit.
The
directional
unit
may
be polarized
from
a
source
of potential,
or
current,
or both
sources
may be
used to
dual
polarize
the
unit.
It
is
advantageous
to use
dual
polarization
because
changing
system
conditions
may
cause
current
polarization
to
be
favored at
some
times
whereas
voltage
polarization
might
be
favored at others.
Figure
13
illustrates
the
effect
of
using
dual
polarization
as
compared
to
polarization
from
a
source
of
voltage
or
current
alone.
The
differences
between
the
various
models
covered
by
this instruction
book
are
shown
in
Table I.
Inverse
time
relays should
be used
on
systems
where
the fault
current
flowing through
a
given relay is
influenced
largely
by the
system
generating
capacity
at
the
time
of
the fault.
Very
inverse
time
and
extremely
inverse
time
relays
should
be
used in
cases
where
the fault
current
magnitude
is
dependent
mainly
upon
the
location
of
the
fault in
relation
to
the relay,
and
only
slightly
or
not at
all
upon
the
system
generating
setup.
The
reason
for
this
is
that
relays
must
be
set
to be
selective
with
maximum
fault current
flowing.
For
fault
currents
below
this value,
the operating
time
becomes
greater
as the
current
is
decreased.
If
there
is
a
wide range
in
generating
capacity,
together
with
variation
in
short-
circuit-current
with
fault
position,
the
operating
time with
minimum
fault
current
may be
exceedingly
long
with very
inverse
time relays
and
even
longer
with extremely
inverse
time
relays.
For
such cases,
the
inverse
time
relay
is more
applicable.
The
operating
time
of
the time
overcurrent
unit for
any given
value of
current
and
tap setting
is determined
by
the
time-dial
setting.
The
operating
time is inversely
proportional
to the
current magnitude
as illustrated
by
the time
curves
in Figures
4

G[K-49822
15, 16
and 17.
Note
that the current
values
on these curves
are given
as
multiples
of
the tap
setting.
That is, for
a given
time-dial
setting,
the time
will
be the
same
for
80 amperes on
the
8
ampere
tap as
for 50
amperes
on
the 5
ampere
tap, since
in
both
cases the current
is
10
times setting.
If
selective
action
of
two
or more relays
is required, determine
the
maximum
possible
short-circuit
current
of
the
line and then
choose
a
time value
for
each
relay that
differs sufficiently
to
insure
the
proper
sequence
in the operation
of
the several
circuit
breakers.
Allowance
must be made
for the
time involved
in
opening
each breaker
after the relay contacts
close.
The
ViA
relays
contain a
Hi-Seismic instantaneous
overcurrent
unit.
This unit may
be set high to
trip directly
for faults some
distance
down
the transmission
line.
In determining
the setting for
this
unit,
it
will
be necessary
to consider
faults
directly
behind
the relay
as
well
as
at the
remote
terminal, because
the
unit
is
non-directional.
The unit
should be set
with
a suitable amount
of
margin
above
the
maximum
external fault current.
The
effects
of
transient
overreach,
as
illustrated
in
Figure
19, should also
be taken into account
in
determining
the
setting.
RATINGS
The IBCG
relays described
in
this instruction
are available in
50 and 60
hertz
models.
The TOC (time
overcurrent)
units
have extended
(8-to—i) range
similar
to
the 800 series
IAC
relays. The
IOC (instantaneous
overcurrent)
units, when
used
(see
Table
I), have extended
(25—to-i) range.
Ratings
of
the
operating
current
circuits
of
the TOC,
JOC
and
the
directional units
are shown individually.
However,
since
all
operating
current circuits
are
normally connected
in
series, the
operating
coil ratings
of all units
should
be
considered in determining
the rating
of
the
entire
operating circuit.
TABLE H
ONE
SECOND RATING OF
TOC UNITS
Relay
Range
One
Second
Model
(Amps)
Rating (Amps)
IBCG51M
0.5-4.0
70
IBCG51M(—
)V1A
IBCG52M
2.0-16
260
IBCG53M
0.5—4.0
140
IBCG53M(-
)Y1A
IBCG54M
1.5-12
260
IBCG77M
0.5-4.0
125
IBCG78M
1.5-12
260
5

GEK—49822
TIME
OVERCURRENT
UNIT
The
1
second
ratings
of
the
TOC
units
are
given
in
Table
II.
The
continuous ratings
for
the
various
taps of
each
model
and
current
range
are
given
in
Tables
III,
IV
and
V.
TABLE
III
CONTINUOUS RATING
OF 0.5-4.0 AMP
TOC
UNITS
0.5-4.0
Amp
Range
Model
Tap
0.5
0.6
0.7 0.8
1.0
1.2
1.5
2.0
2.5 3.0 4.0
IBCG51M
IBCG51M(-)Y1A
Rating
1.6
1.8
2.0
2.1
2.3 2.7
3.0
3.5
4.0
4.5 5.0
IBCG5?M
(Amps)
IBCG53M
IBCG53M(—)Y1A
4.0
4.5
5.5
5.5
6.0 7.0 7.5
9.0
10.0
11.0 13.0
IBCG54M
IBCG77M
IBCG78M
3.5
3.7
4.0
4.5
5.0
5.5
6.0 7.0
8.0
9.0
10.0
TABLE
IV
CONTINUOUS
RATING
OF
1.5-12.0
AMP TOC
UNITS
1.5-12.0
Amp
Range
Model
Tap
1.5
2.0
2.5
3.0
4.0
5.0
6.0
7.0
8.0
10.0
12.0
IBCG53M
Rating
IBCG53M(-)Y1A
10.0
11.5
13.0
14.5
17.0
19.0
21.0 23.0
23.5 27.5
30.5
IBCG54M
(Amps)
r
IBCG77M
IBCG78M
9.5
10.5 11.5
12.5 14.0
15.5
17.0
18.0 19.0
20.0 20.0
6

GEK-49822
TABLE
V
CONTINUOUS RATING
OF
2-16.0 AMP TOC
UNITS
2-16.0
Amp
Range
Model Tap
2.0 2.5
3.0 4.0
5.0
6.0 7.0
8.0 10.0 12.0
16.0
IBCG51M
Rating
IBCG51M(-)Y1A
8.0
9.0 10.0
12.0
14.0 15.0
16.0
17.5
20.0 20.0
20.0
IBCG52M
(Amps)
9.5
10.5 11.5 12.5
14.0
15.5
17.0
18.0 19.0 20.0 20.0
DIRECTIONAL
UNIT
The
directional unit
current
polarizing
and operating
coils have a
continuous rating
of
5 amperes and a 1
second rating
of 150 amperes.
The potential
polarizing coils
will
withstand
120
volts continuously
and
360
volts
for 60
seconds.
INSTANTANEOUS
UNIT
The
instantaneous unit
coil is of
the
hinged
armature construction
and is
tapped
for
operation on either
one of two ranges
(H or L).
Selection of the
high or low
range
is
accomplished
by the
positioning of leads
T
and
E
at terminal
6.
See Table VI
and
the applicable
internal
connections
diagrams
referred
to in
Table
I.
For
the H
range,
connect lead
T
to
terminal 6
and
lead
E
to
the
auxiliary
terminal
that is
mounted on terminal
6.
For
range
L,
reverse
leads
T
and
E.
TABLE
VI
CONTINUOUS
AND ONE
SECOND
RATINGS
OF lOG
UNIT
One
Continuous
Second
Instantaneous
Range
Rating Rating
Unit
(Amps)
Range
(Amps)
(Amps) (Amps)
6-150
L 6
- 30
10.2 260
H 30
- 150 19.6
**
The range
is
approximate,
which means that
6-30,
30-150 may be
6—29,
28-150. There
will
always
be
at
least
1 ampere overlap between
the maximum
L
setting and
the
minimum
H setting.
Whenever
possible,
be sure
to select the higher range,
since it
has the higher continuous
rat i
n
g.
7

GEK-49822
TARGET
AND
SEAL-IN
UNIT
The
rating
and
impedance
of
the
seal-in
unit
for
the
0.2
and
2
ampere
taps
are
given
in
Table
VII.
The
tap
setting
used
will
depend
on
the
current
drawn
by
the
trip
coil.
TABLE
VII
SEAL-IN
UNIT
RATINGS
TAP
0.2
—
2.0
DC
RESISTANCE
+10%
(OHMS)
8.3
0.24
MIN
OPERATING
(AMPERES)
+0-25%
0.2 2.0
CARRY
CONT.
(AMPERES)
0.37
2.3
CARRY
30 AMPS
FOR
(SEC.)
0.05
2.2
CARRY
10
AMPS FOR
(sEC.)
0.45
20
60
Hz
IMPEDANCE
(OHMS)
50.0
0.65
The
0.2
ampere
tap
is
for
use
with
trip
coils
which
operate
on
currents
ranging
from
0.2
up
to
2.0
amperes,
at
the
minimum
control
voltage.
If
this
tap is
used
with
trip
coils
requiring
more
than
2
amperes,
there
is
a
possibility
that
the
resistance
of
7
ohms
will
reduce
the
current
to
so
low
a
value
that
the
breaker
will
not
be
tripped.
The
2.0
ampere
tap
should
be
used
with
trip
coils
that
take
2
amperes
or
more
at
minimum
control
voltage,
provided
the
current
does
not
exceed
30
amperes
at
the
maximum
control
voltage.
If
the
tripping current
exceeds
30
amperes,
the
connec
tions
should
be
arranged
so
that
the
induction
unit
contacts
will
operate
an
auxili
ary
relay,
which
in
turn
energizes
the
trip
coil
or
coils.
On
such
an
application,
it
may
be
necessary
to
connect
a
loading
resistor
in
parallel
with
the
auxiliary
relay
coil
to
allow
enough
current
to
operate
the
target
seal-in
unit.
CONTACTS
The
current-closing
rating
of
the
induction
unit
is
30
amperes
for voltages
not
exceeding
250
volts.
Their
current-carrying rating
is
limited
by
the
tap
rating
of
the
seal—in
unit.
CHARACTERISTI
Cs
PICKUP
When
potential polarized,
the
directional
unit
will
pick
up
at
3.6
volts-amperes
at
the
maximum
torque
angle
of
60°
lag
(current
lags
voltage).
When
current
polarized,
it
will
pick
up
at
approximately
0.5
ampere
with
the
operating
and
polarizing
coils
connected
in
series.
The
performance
of
the
unit
with
simultaneous
current
and
potential
polarization
is
typified
in
Figure
13.
8

GEK—49822
The
current
required
to close
the time
overcurrent
unit
contacts
will be
within
5%
of
the tap screw
setting.
RESET
(TIME
OVERCURRENT UNIT)
Inverse
time overcurrent
units reset at
90%
of
the
minimum
pickup
current, very
inverse
time
units at
80%,
and
extremely
inverse time
units
at
85%.
When the
relay is
de-energized,
the time required
for the disk
to
completely
reset
to the
number 10 time
dial
position
is approximately
6
seconds
for inverse time
relays,
and 60 seconds
for very
inverse
time and
extremely
inverse
time
relays.
OPERATING
TIME
The time curve
for the directional
unit is
shown
in Figure
14.
The
time
curves
of the
time
overcurrent
unit are shown in
Figures
15, 16
and 17,
respectively
for inverse,
very inverse
and extremely
inverse
time relays.
For the
same
operating
conditions, the
relay will operate
repeatedly
within
1
or 2%
of the
same
time.
The
time-current
characteristic
of
the Hi-Seismic
instantaneous
unit
is shown
by
Figure
18 and its
transient
overreach
characteristic is
shown
by Figure 19.
BURDENS
The
capacitive
burden of
the potential polarizing
circuit of
the directional
unit
at
60 cycles
and 120 volts
is
10
volt amperes
at 0.86
power factor. Table
VIII
gives
the
current
circuit burdens of
the directional
unit.
TABLE
VIII
DIRECTIONAL UNIT
CURRENT
CIRCUIT
BURDEN AT 60
CYLES AND 5
AMPERES
Circuit
Z
(Ohms) VA
P.F Watts
perating
0.46 12.0
0.52 6.24
Polarizing 0.24
6.0
0.95
5.27
Table
IX gives
the
current circuit
burdens
of
time
overcurrent
units.
Ordinarily
the potential
circuit
is in the
open
corner of
broken
delta potential
transformers
and
the
current
circuits
are in
the
residual
circuits
of
current
transformers.
The burden
is, therefore,
only
imposed
for
the
duration of
the
ground
fault
and need
be considered
only for this
brief
period. Table
X gives
the burden
of
the
instantaneous
unit.
9

GEK-49822
TABLE IX
CURRENT CIRCUIT
BURDENS AT
60
CYCLES OF THE TOC
UNIT
Tap Burdens at Minimum Pickup Ohms
Impedance at
*VA
Time
Range
Eff.Res. React.
**Imped
+Volt 3
Times 10
Times
At
Fivc
Characteristic
(Amps) (Ohms) (Ohms)
(Ohms) Amps
P.F. Mm P.U. Mm P.U.
Amperes
Inverse 0.5/4
5.60 21.0 22.0
5.5 0.25 10.80
5.00 555.0
Inverse 2/16 0.37 1.44
1.49 5.8
0.25 0.65
0.32
36.3
Very Inverse 0.5/4 1.40 3.90 4.15 1.0 0.33 4.20 2.90 104.0
Very
Inverse
1.5/12
0.23 0.53 0.58
1.3
0.40
0.58 0.36
14.5
Extr. Inverse 0.5/4 0.80 1.38 1.60 0.4 0.50
1.60 1.60 40.0
Extr. Inverse
1.5/12 0.005
0.147
0.17 0.4
0.50
0.17 0.17 4.25
**The
impedance
values
given are those
for the minimum tap of each
relay.
The impedance
for other
taps, at pickup
current
(tap rating),
varies
inversely approximately
as
the
square of
the current
rating. Example:
for the
Type IBCG51M relay,
0.5/4
amperes, the impedance
of the 0.5
ampere
tap is 22
ohms.
The
impedance
of
the 1
ampere tap, at 1
ampere,
is
approximately
(0.5/1)2
x 22
= 5.5
ohms.
+
Some
companies list
relay burdens only
as the
volt-ampere input to
operate
at
minimum pickup. This
column
is included so a
direct comparison
can be
made.
It
should
not be used
in
calculating
volt—ampere burdens
in
a
CT secondary
circuit,
since
the
burden
at
5
amperes
is
used for this
purpose.
4
Calculated from
burden at
minimum pickup.
TABLE X
BURDEN
OF
THE INSTANTANEOUS UNIT
Inst.
Mm. Burden at
Mm Burden
Ohms
(Z)
Unit
Range
Pickup Pickup
(Ohms)
Times Pickup
Amps
Hz
Range
Amps Amps
R
Z
3 10 20
6-150 60
L 6-30
6
0.110 0.078
0.135 0.095
0.081 0.079
H
30-150 30 0.022 0.005
0.023 0.022 0.022 0.222
10

GEK-49822
CONSTRU
CTI ON
The IBCG
relays
consist
of two
units, a
time
overcurrent
unit
(top) of
the
induction
disk
type,
and an
instantaneous
power
directional
unit (bottom)
of
the induction
cup
type. The
directional
unit
is either
potential
or current
polarized
or
both and,
by
means
of
its
closing
contacts,
directionally
controls
the
operation
of
the
time
overcurrent
unit.
The
IBCG relays
have
a target
seal—in
unit
and models
with
the ViA
suffix,
as shown
by Table
I,
have
a
hinged-armature
type
instantaneous
overcurrent
unit.
The
IBCG relays
are
mounted in
the single-ended
Mi
drawout
case.
DIRECTIONAL
UNIT
The
directional
unit
is of
the induction—cylinder
construction
with
a
laminated
stator
having
eight poles
projecting
inward
and
arranged
symmetrically
around
a
stationary
central
core.
The cuplike
aluminum
induction
rotor
is free
to
operate
in
the
annular
air
gap
between
the
poles
and
the
core. The
poles
are fitted
with
current-operating,
current—polarizing
and potential—polarizing
coils.
The
principle
by
which
torque
is developed
is
the same
as that
of an
induction disk
relay
with
a
wattmetric
element,
although,
in arrangement
of parts,
the unit
is more
like
a split-phase
induction
motor.
The induction-cylinder
construction
provides
higher
torque and
lower
rotor
inertia
than
the
induction-disk
construction,
resulting
in
a
faster
and
more sensitive
unit.
CONTACTS
The
directional
unit contacts
that
control
the
time overcurrent
unit
are shown
in
Figure
20.
They are
of
the
low gradient
type,
specially
constructed
to minimize
the
effects
of vibration.
Both
the
stationary
and moving
contact
brushes are
made
of
low
gradient
material
which,
when
subjected
to
vibration,
tend
to follow
one
another,
hence,
they resist
contact
separation.
The
contact
dial (A)
supports
the
stationary
contact
brush
(B)
on which
is mounted
a
conical
contact
tip
(C).
The
moving
contact
arm
(D)
supports the
moving
contact
brush
(E)
on
which is
mounted
a
button
contact
tip
(F).
The
end
of
the moving
contact
brush
bears against
the
inner
face
of the moving
contact
brush
retainer
(G).
Similarly,
the end
of
the
stationary
contact
brush
bears
against the
inner
face
of
the
stationary
contact
brush
retainer
(H).
The stop
screw
(J),
mounted
on
the
contact
dial,
functions
to
stop the
motion of
the
contact
arm by
striking
the moving
contact
brush
retainer
after
the moving
and stationary
contact
members
have
made
contact.
The
stationary
contact
support
(K)
and the
contact
dial are
assembled
together
by
means of
a mounting
screw
CL)
and
two
locknuts
(M).
TIME
OVERCURRENT
UNIT
The
inverse
time
and
very
inverse
time
overcurrent
units consist
of
a
tapped
current-operating
coil
wound on
a
U-magnet
iron
structure.
The
tapped
operating
coil
is
connected
to taps
on the
tap
block.
The
U-magnet
contains
wound
shading
coils
which are
connected
in
series
with a
directional
unit contact.
When
power
flow
is in such
a direction
as
to close
the
directional
unit
contacts,
the
shading
coils
act
to
produce
a
split-phase
field
which, in
turn,
develops
torque
on
the
operating
disk.
11

GEK-49822
The
extremely
inverse
time
overcurrent
unit
is
of
the
wattmetric
type
similar
to
that
used
in
watthour
meters except
as
follows:
the
upper
portion
of
the iron structure
has
two
concentric
windings
on
the
middle
leg of the
magnetic
circuit.
One
of these
is
a
tapped
current
winding
connected
to
taps
on
the
tap
block;
the
other
is
a
floating
winding
which
is
connected
in
series
with
the
directional
unit
contacts,
a
resistor,
a
capacitor
and
the
two
coils
on
the
lower
legs
of
the
magnetic
circuit.
When
power
flow
is
in
such
a
direction
as
to
close
a directional
unit contact,
the
unit
develops
torque
on
the
operating
disk.
The
disk
shaft
carries
the
moving
contact
which
completes
the
trip circuit
when
it
touches
the
stationary
contact
or
contacts.
The
shaft
is
restrained
by
a
spiral spring
to
give
the
proper
contact-closing
current,
and
its
motion
is
retarded
by
a
permanent
magnet
acting
on
the disk
to
produce
the
desired
time
characteristic.
The
variable
retarding
force
resulting
from
the
gradient
of
the
spiral
spring
is
compensated
by
the
spiral
shape
of
the
induction
disk,
which
results
in
an
increased
driving
force
as
the
spring
winds
up.
TARGET
SEAL-IN
UNIT
A
seal-in
unit
is
mounted
on
the
left
side
of
the
time
overcurrent
unit.
This
unit
has
its
coil
in
series
and
its
contacts
in
parallel
with
the
main
contacts
of
the overcurrent
unit,
arranged
in
such
a
manner
that
when
the
main
contacts
close,
the
seal-in
unit
picks
up
and
seals—in
around
the
main
contacts.
When
the
seal—in
unit
operates,
it
raises
a
target
into
view
which
latches
up
and
remains
exposed
until
manually
released
by
pressing
the
button
located
at
the
lower
left
corner
of
the
cover.
INSTANTANEOUS
UNIT
The
IOC
unit
is
a
small
hinged-armature-type
instantaneous
element
and
is
mounted
on
the
right
side
of
the
TOC
unit.
The
bC
element
operates
over
a
25-to-i
total
range
obtained
by using
a
tapped
coil
which
provides
a
5-to-i
low
range
and
a
5-to-i
high
range;
this
combination
provides
the
25-to-i
total
range.
When
the
current
reaches
a
predetermined
value,
the
instantaneous
element
operates,
closing
its
contact
circuit
and
raising
its
target
into
view.
The
target
latches
in
the
exposed
position until
it
is
released.
The same
button
that
releases
the
target
seal—in
unit
also
releases
the
target
of
the
instantaneous
unit.
RECEIVING.
HANDLING
AND
STORAGE
These
relays,
when
not
included
as
part
of
a
control
panel,
will
be
shipped
in
cartons
designed
to
protect
them
against
damage.
Inmiediately
upon
receipt
of
a
relay,
examine
it
for
any
damage
sustained
in
transit.
If
injury
or
damage
resulting
from
rough
handling
is
evident,
file
a
damage
claim
at
once
with
the
transportation
company
and
promptly
notify
the
nearest
General
Electric
Sales
Office.
Reasonable
care
should
be
exercised
in
unpacking
the
relay
in
order
that
none
of
the
parts
are
injured
or
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.
Foreign
matter
collected
on
the
outside
of
the
case
may
find
its
way
inside
when
the
cover
is
removed,
and
cause
trouble
in
the
operation
of
the
relay.
12

GEK-49822
ACCEPTANCE
TESTS
Immediately
upon
receipt
of
the
relay
an
INSPECTION
AND ACCEPTANCE
TEST
should
be
made
to
ensure
that no
damage
has
been sustained
in
shipment
and
that
the relay
calibrations
have
not
been
disturbed.
If
the examination or the
test
indicates
that
readjustment is
necessary,
refer
to
the
section
on SERVICING.
Since
operating
conipanies
use different
procedures
for acceptance
and
installation
tests,
the following
section
includes
all
applicable
tests
that
may be
performed
on
these
relays.
These tests
may
be performed as
part of
the
installation or
acceptance
tests,
at the
discretion
of
the user.
VISUAL
INSPECTION
Check
the nameplate
stamping
to
ensure
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
molded
parts
or
other
signs of
physical
damage and
that
all screws
are tight.
Check
that
the
shorting
bars
are in the
proper
location(s)
as
shown
by the
internal
connec
tions
diagrams,
Figures
5
to
9,
inclusive,
and
that
the
main
brush
is properly
formed
to contact
the shorting
bar.
MECHANICAL
INSPECTION
Top Unit
(TOC)
1. The
disk
shaft
end
play
should
be 0.005—0.015
inch.
2.
The
disk should
be centered
in the
air
gaps
of
both the
electromagnet
and
drag
magnet.
3.
Both
air gaps
should
be free
of
foreign
matter.
4.
The
disk
should
rotate freely
and
should
return
by
itself
to
the reset
position.
5.
The moving
contact
should
just
touch
the stationary
contact
when
the
time
dial
is
at
the
0
time dial
position.
Bottom
Unit
(DIR)
1.
The
rotating
shaft end
play should
be 0.015—0.020
inch.
2.
The contact
gap
should
be 0.015—0.025
inch
on
the low
gradient
contact.
Target
and Seal-in
Unit/Instantaneous
Unit
1. The
armature
and contacts
should move
freely when
operated
by hand.
2.
Both contacts
should
make
at
approximately
the same
time.
3.
The
target
should
latch
into
view just
as
the
contacts
make and
should unlatch
when the
target
release
button
is operated.
4.
The contacts
should
have
approximately
0.030
inch
wipe.
13

GEK-49822
DRAWOUT
RELAYS,
GENERAL
Since
all
drawout
relays
in
service
operate
in
their
cases,
it
is recommended
that
they
be
tested
in
their
cases
or an
equivalent
steel
case.
In
this
way,
any
magnetic
effects
of
the
enclosure will
be
accurately
duplicated during
testing.
A
relay
may
be
tested
without
removing
it
from
the
panel
by
using
a
12XLA13A test
plug.
This
plug
makes
connections
only
with
the
relay
and
does
not
disturb
any
shorting
bars
in the
case.
The
12XLA12A
test
plug
may
also
be
used.
Although
this
test
plug
allows
greater
testing
flexibility,
it
requires
CT
shorting
jumpers
and
the
exercise
of
greater
care,
since
connections
are
made
to
both
the
relay
and
the
external
circuitry.
POWER
REQUIREMENTS,
GENERAL
All
alternating—current-operated
devices
are
affected
by
frequency. Since
non—
sinusoidal
waveforms
can
be
analyzed
as a
fundamental
frequency plus
harmonics
of
the
fundamental
frequency,
it
follows
that
alternating-current
(AC)
devices (relays)
will
be
affected
by the
applied
waveform.
Therefore,
in
order
to
test
alternating
current
relays properly,
it is
essential
to
use
a
sine
wave
of
current
and/or
voltage.
The
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,
R-L
or
RC
networks,
or
saturating
electromagnets
(such
as
time
overcurrent relays)
is
affected
by
non—sinusoidal
waveforms.
TARGET
AND
SEAL-IN
UNIT
The
target
and
seal-in
unit
has
an
operating
coil
tapped
at 0.2
and
2.0 amperes.
When
used
with
trip
coils
operating
on
currents ranging
from
0.2
to
2.0
amperes at
the
minimum
control
voltage,
the
target
and
seal-in
tap
screw
should
be
set
in
the
0.2
ampere
tap.
When
the
trip
coil
current
ranges
from
2 to
30
amperes
at
the
minimum
control
voltage,
the tap
screw
should
be placed
in the
2.0
ampere
tap.
The
seal-in
tap
screw
is the
screw
holding
the
right-hand
stationary
contact of the
seal-in
unit.
To
change
the
tap
setting,
first
remove
the
connecting
plug.
Then
take
a
screw
from
the
left-hand
stationary
contact
and
place
it in
the
desired
tap.
There
will
now
be
screws
in
both
taps.
Next,
remove the
screw
from
the
other
(undesired)
tap
and
place
it
back
in the
left—hand contact.
This
procedure
is
necessary
to
prevent
the
right—hand
stationary
contact from
getting
out
of
adjustment.
Tap
screws
should
never
be allowed
to
remain
in
both
taps
at
the
same
time.
Pickup
and
Dropout
Test
1.
Connect
relay
studs
1 and
2
(see
internal
connections diagram)
to
a DC
source,
ammeter
and
load
box
so that
the
current
can
be
controlled over
a
range
of 0.1
to
2.0
amperes.
2.
Close
or
jumper
the
contact(s)
that
parallel
the
seal-in
unit
contact.
3.
Increase the
current
slowly
until
the seal-in
unit
picks
up.
See
Table
XI.
4.
Open
the
parallel
contact
circuit
of step
2; the
seal-in
unit
should
remain
in
the
picked
up
position.
5.
Decrease
the
current
slowly
until
the seal—in
unit
drops
out.
See
Table
XI.
14

GEK-49822
TABLE
XI
TARGET
AND
SEAL-IN
UNIT
OPERATING
CURRENTS
PICKUP
DROPOUT
TAP
CURRENT CURRENT
0.2
0.115
-
0.195
0.05
OR
MORE
2.0
1.15
-
1.95
0.55
OR
MORE
TIME
OVERCURRENT
UNIT
Rotate
the
time
dial
slowly
and
check
by
means
of
a
lamp
that
the
contacts
just
close
at
the
0
time—dial
setting.
Where
the
contacts
just
close
can
be
adjusted
by
running
the
stationary
contact
brush
in
or
out
by
means
of
its
adjusting
screw.
This
screw
should
be
held
securely
in
its
support.
With
the
contacts
just
closing
at
No.
0
time—dial
setting,
there
should
be
sufficient
gap
between
the
stationary
contact
brush
and
its
metal
backing
strip
to
ensure
approximately
1/32
inch wipe.
Current
Setting
The
minimum
current
at
which
the
time
overcurrent
unit
will
close
its
contacts
is
determined
by
the
position
of
the
plug
in
the
tap
block.
The
tap
plate
on
this block
is
marked in
amperes,
as
shown
in
Tables
III,
IV
and
V.
When
the
tap
setting
is
changed
with
the
relay
energized
in
its
case,
the
following
procedure
must
be
followed:
(1)
Remove
the
connecting plug;
this
de-energizes
the
relay
and
shorts
the
current
transformer
secondary
winding.
(2)
Remove
the
tap
screw
and
place
it
in
the tap
marked
for
the
desired
pickup
current.
(3) Replace
the
connecting
plug.
The
minimum
current
required
to
rotate
the
disk
slowly
and
to
close
the
contacts
should
be
within
5%
of the
value
marked
on
the
tap
plate
for
any
tap
setting
and
time
dial
position.
If
this
adjustment
has
been
disturbed,
it
can
be
restored
by
means
of
the
spring
adjusting
ring.
The
ring
can
be
turned
by
inserting
a
screw
driver
blade
in
the
notches
around
the
edge.
By
turning
the
ring,
the
operating
current
of
the
unit
can
be
brought
into
agreement
with
the
tap
setting
employed.
This
adjustment
also
permits
any
desired
setting
to
be
obtained
intermediately
between
the
available
tap
settings.
Pickup
adjustment
by
means
of
the
control
spring
applies
to
the
IBCG51/52
and
IBCG53/54
relays.
A
different
procedure
applies
to
the
IBCG77/78
relays.
For
the
IBCG77/78
relays,
the
pickup
of
the
unit
for
any
current
tap
setting
is
adjusted
by
means
of
the
variable
resistor
in
the
phase-shifting
circuit.
This
adjustment
also
permits
any
desired
setting
intermediate
between
the
various
tap
settings
to
be
obtained.
The
control
spring is
prewound
approximately
6600
with
the
contacts
just
closed.
Further
adjustment
of
this
setting
is
seldom
required;
if
it
is
required,
15

GEK—4
9822
because
of
the
insufficient
range
of
the
variable
resistor,
it
should never
be
necessary
to
wind
up the
control
spring
adjuster
more
than
300
(1
notch) or
unwind
it
more
than
900
(3
notches)
from
the
factory
setting.
Test Connections
for making
pickup
and
time
checks
on
the
time
over-current
unit
are
shown
in
Figures
22
and
23.
Use
a
source
of
120
volts
or
greater
with
good wave
form and
constant
frequency.
Stepdown
transformers
or
phantom
loads
should
not
be
employed
in
testing
induction
relays
since
their
use
may
cause
a
distorted
wave
form.
The
contact
in
the
wound
shading
coil
circuit
marked
D,
see
internal
connection
diagram,
must
be
blocked
closed
or
jumpered
for
both
the
pickup
test
and
the
time
test.
Time
Setting
The
setting
of
the
time
dial
determines
the
length
of
time
the
unit
requires
to
close
its
contacts
when
the
current
reaches
a
predetermined
value.
The
contacts
are
just
closed
when
the
dial
is
set
on
0.
When
the
dial
is
set
on
10,
the
disk
must
travel
the
maximum
amount
to
close
the
contacts
and
therefore
this setting
gives
the
maximum
time
setting.
The
primary
adjustment
for
the
time
of operation
of the
unit
is
made by
means
of
the
time
dial.
However,
further
adjustment
is obtained
by
moving
the
permanent
magnet
along
its
supporting
shelf;
moving
the
magnet
toward
the
disk
shaft
decreases
the
time,
while
moving
it away
increases
the
time.
Be
sure
the
magnet
never
extends out
beyond
the
cutout
in
the
disk.
Pickup
Test
Use
rated
frequency
for
both
the
pickup
and
time
tests.
The
directional
unit
contact
must
be
closed
to
perform
the
pickup
and
time
tests.
Set
the
relay
at
the
0.5
time-dial
position
and
2.0
ampere
tap.
Using
the
test
connection
in
Figure
22,
the
main
unit
should
close
its
contacts
within
+
2.0%
of
tap
value
current
(1.96—2.04
amps).
Time
Test
Set
the
relay
at
No.
5
time—dial
setting
and
the
2.0
amp
tap.
Using
the
test
connection
in
Figure
23,
apply
5
times
tap
current
(10.0
amp)
to
the
relay.
The
relay
should
operate
within
the
limits
given
in Table
XII.
TABLE
XII
TOC
UNIT OPERATING TIME
LIMITS
Time
in Seconds
Relay
Type
Mm.
Midpoint
Max
IBCG51-IBCG52
1.72
1.78
1.83
IBCG53-IBCGS4
1.27 1.31
1.35
18CG77-IBCG78
0.89
0.92 0.95
16

GEK-49822
DIRECTIONAL UNIT
Current
Polarization
a.
Connect
per
Figure
24
test
connections.
b.
The
unit
should
close
its
contacts
within
5%
of
0.5
ampere.
The
clutch
should
slip
between
8-18
amperes.
I
CAUTION
This
level
of
current
can
overheat
the
coil
if
applied
too
frequently
or
for
too
long
a period
of
time.
Potential
Polarization
a.
Connect
per
Figure
25
test
connections.
b.
With
V
set
for
5
volts
at terminals
9
to
10.
the
unit
should
close
its
contacts
between
0.75-1.75
amps.
INSTANTANEOUS
UNIT
Make
sure
that
the
instantaneous
unit
is
in
the
correct
range
in
which
it
is
to
operate.
See
the
internal
connections
diagram
and
Table
VI.
Whenever
possible,
use
the
higher
range
since
the
higher
range
has
a
higher
continuous
rating.
The
instantaneous
unit
has
an
adjustable
core
located
at
the
top
of the
unit.
To
set
the
instantaneous
unit
to
a desired
pickup,
loosen
the
locknut
and
adjust
the
core.
Turning
the
core clockwise
decreases
the pickup;
turning
the
core
counterclockwise
increases
the
pickup.
Bring
up
the
current
slowly
until
the
unit
picks
up.
It
may
be
necessary
to
repeat
this
operation,
until
the
desired
pickup
value
is
obtained.
Once
the
desired
pickup
value
is
reached,
tighten
the
locknut.
F
CAUTION
Refer
to
Table
VI
(p.7)
for
the
continuous
and
1
second
ratings
of
the
instantaneous
unit.
Do
not
exceed
these
ratings
when
applying
current
to
the
instantaneous
unit.
The
range
of
the
instantaneous
unit
(see
Table
VI)
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.
INSTALLATION
LOCATION
The
location
should
be
clean
and
dry,
free
from
dust
and
excessive
vibration
and
well
lighted
to
facilitate
inspection
and
testing.
17

GEK-49822
MOUNTING
The
relay should
be mounted
on
a
vertical
surface.
The
outline
and panel
drilling
diagram
is shown
in
Figure
26.
CONNECTIONS
The internal
connection
diagrams
for the
various
relays
are
shown
in
Figures
5
to
9.
Typical
external
wiring
diagrams
are
shown by
Figures
10, 11
and 12.
Unless
mounted
on
a steel
panel which
adequately
grounds
the
relay
case,
it is
recomended
that the
case
be
grounded
through
a mounting
stud
or screw
with
a
conductor
not less
than
1/12
B&S
gage copper
wire
or its
equivalent.
INSPECTION
At
the time
of installation,
the relay
should be
inspected
for
tarnished
contacts,
loose screws,
or other
imperfections.
If
any
trouble
is
found,
it
should
be
corrected
in
the manner
described
in the section
on SERVICING.
CAUTION
Every
circuit
in
the
drawout
case
has
an auxiliary
brush.
It
is
especially
important
on current
circuits
and other
circuits
with
shorting
bars
that
the
auxiliary
brush
be bent
high
enough
to
engage
the
connecting
plug
or
test plug
before
the
main
brushes
do. This
will
prevent
CT
secondary
circuits
from
being
opened.
Refer
to Figure
21.
OPERATION
Before
the
relay
is put into
service,
it
should
be given
a
check
to
determine
that
factory
adjustments
have
not
been disturbed.
The
time
dial will
be
set
at
0
before
the
relay
leaves
the
factory.
If the setting
has
not
been changed,
it
will be
necessary
to change
this
setting
in
order
to
open
the
time
overcurrent
unit
contacts.
The following
tests
are
suggested:
TARGET
AND SEAL-IN
UNIT
1.
Make
sure that
the tap
screw
is
in
the desired
tap.
2.
Perform
pickup
and dropout
tests as
outlined
in
the
ACCEPTANCE
TEST
section.
TIME
OVERCURRENT
UNIT
1.
Set
tap
screw
on
desired
tap.
Using
the
test circuit
in
Figure 22,
apply
approximately
twice
tap
value current
until
the
contacts
just
close.
Reduce
the
current
until
the light
in series
with
the
contacts
begins
to
flicker.
This
value
of
current
should
be within
5%
of
tap
value.
2.
Check
the
operating
time
at
some
multiple
of tap value.
This
multiple
of
tap
value
may
be
5
times
tap rating
or
the
maximum
fault
current
for which
the
relay
must
coordinate.
The
value
used is
left
to the discretion
of the
user.
Use
the
test circuit
shown
in
Figure 23.
18

GEK—49822
DIRECTIONAL
UNIT
Current
Polarization
a.
Connect
per
Figure
24
test
connections.
b.
Adjust
the
control
spring
for
0.5 ampere
pickup
if
current
polarized
or
dual
polarized.
Potential Polarization
c.
If
potential
polarized,
connect
per Figure
25
test
connections.
d.
Adjust
the
control
spring
or
7.2
volt
amperes
(±10%)
since
the
relay
is
6O
from
the
angle
of
maximum
torque.
10
volts
and
0.72
amperes
are
recommended
values
for
this
test.
INSTANTANEOUS
UNIT
1.
Select
the
desired
range
by making
the proper
connections
at
the
rear
of
the
relay
(see
internal
connections
diagram).
Whenever
possible,
be sure
to
select
the higher
range
since
it
has
a higher
continuous
rating.
2.
Set
the instantaneous
unit
to pick
up
at
the
desired
current
level.
See
the
ACCEPTANCE
TEST
section.
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
users
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.
These
tests
are intended
to
ensure
that
the
relays
have
not deviated
from
their
original
settings.
If deviations
are
encountered,
the
relay
must
be
retested
and
serviced
as
described
in
this manual.
TARGET
AND SEAL-IN
UNIT
1.
Check
that
the
unit
picks
up at
the values
shown
in
Table
X.
2.
Check
that
the
unit
drops
out
at
25% or
more of
tap value.
TIME
OVERCURRENT UNIT
1.
Perform pickup
test
for
the tap
in
service,
as described
in
the
OPERATION
section.
2.
Perform
the time
tests
as
described
in
the
OPERATION
section.
DIRECTIONAL
UNIT
Repeat
the portion
of the
ACCEPTANCE
TEST
for
the
polarity
condition
for
which
the
relay
is
connected
in
service.
19

GEK-49822
INSTANTANEOUS
UNIT
Check
that
the
instantaneous
unit
picks
up
at
the
desired
current
level,
as
outlined
in
the ACCEPTANCE
TESTS
and
the
OPERATION
sections.
SERVICING
These
relays
are
adjusted
at
the
factory
and
it
is advisable
not
to
disturb
the
adjustments.
If, for
any
reason,
they
have
been disturbed
or
it is
found
during
installation
or
periodic
testing
that
the
relay
is
out
of
limits,
the checks
and
adjustments
outlined
in
the
following paragraphs
should
be
observed.
It
is
suggested
that
this
work
be
done
in
the
laboratory.
TARGET
AND SEAL-IN
UNIT
Repeat
the
visual
and mechanical
inspections
and the
pickup
and
dropout
current
checks
as outlined
in
the
ACCEPTANCE
TESTS
section.
TIME
OVERCURRENT
UNIT
Disk
and
Bearings
The
jewel
should
be turned
up
until
the
disk
is
centered
in the
air
gaps,
after
which
it
should
be
locked
in
this
position
by
the
set screw
provided
for
this
purpose.
The
upper
bearing
pin
should
next
be adjusted
so
that
the disk
shaft
has
about
1/64
inch
end
play.
Contact
Adjustment
The
contacts
should
have
about
1/32 inch
wipe.
That
is,
the
stationary
contact
tip
should
be
deflected
about
1/32
inch
when the
disk
completes
its
travel.
Wipe is
adjusted
by
turning
the
wipe
adjustment
screw
on
the stationary
contact,
thereby
adjusting
the
position
of
the
brush
relative
to the
brush
stop.
When
the
time
dial is
moved
to
the
position
where
it
holds
the contacts
just
closed,
it
should
indicate
0
on
the
time-dial
scale.
If
it
does
not
and
the
brushes
are
correctly
adjusted,
shift
the
dial
by
changing
the
position
of
the
arm
attached
to
the
shaft
just
below
the
time
dial.
Loosen
the
screw
clamping
the
arm
to
the
shaft
and turn
the
arm
relative
to
the
shaft
until
the
contacts
just
make
for
0
zero
time-
dial
setting.
Characteristics
Check
and
Adjustments
Repeat
the
portions of
the
ACCEPTANCE
TESTS
section
that
apply
to
the
time
overcurrent
unit.
Also,
check
reset
voltage
and
time
as outlined
under
RESET
in
the
CHARACTERISTICS
section;
low
reset
voltages
or
long
reset
times
may
indicate
excessive
friction
caused
by
a
worn
bearing
or
by mechanical
interference.
20