ABB BL-1 User manual

ABB Power T&D Company Inc.
Relay Division
Coral Springs, FL 33065
Instruction Leaflet
I.L. 41-553.1G
Type BL-1 Thermal
Overload Relay
Effective February 1978
Supersedes I.L. 41-553.1 F dated January 1976
* Denotes change since previous issue
CAUTION: Before putting relays into service,
remove all blocking which may have been inserted
for the purpose of securing the parts during ship-
ment, make sure that all moving parts operate
freely, inspect the contacts to see that they are
clean and close properly, and operate the relay to
check the settings and electrical connections.
APPLICATION
The type BL-I relay is used primarily for
thermal overload and instantaneous overcurrent
protection of motors and generators, but it may
also be used for the protection of transformers or
any other apparatus if the temperature-rise under
overload is similar to that of motors. The thermal
element is the “replica type” and has a time-
current characteristic closely approximating the
average moderate overload heating curves of
motors. Its characteristics prevent the protected
equipment from being subjected to overloads of
such magnitude or duration as to cause them to
reach dangerous temperatures, but at the same
time permit the utilization of the inherent thermal
capacity of the apparatus.
As its operation depends upon the rate of heat
generation in a heater element within the relay, it
may be used for either ac or dc application. It is
ordinarily connected in the secondary circuit of a
suitable current transformer in ac applications.
Since the voltage drop across the relay must be
within a range of about 0.49 to 0.88 volts at full
load on the protected machine, customary shunts
rated in millivolts are unsuited for dc applications.
However,the drop across a portion of the
protected circuit, such as the interpole field win-
ding of a machine, sometimes can be utilized as a
source of energy for the relay.
CONSTRUCTION AND OPERATION
The single element type BL-1 relay consists of
a heater unit, an instantaneous overcurrent unit,
0 two operation indicators, and a contactor switch.
(Figures
1 &
3).
The double element type BL-1 relay contains
two heater units, two instantaneous units, three
0 operation indicators, and a contactor switch.
(Figures 2 & 4).
THERMAL UNIT
The thermal unit consists of a housing of mold-
ed material which encloses a coiled thermostatic
metal spring mounted on a shaft, two die-cut
heater elements made of resistance material, metal
heat storage blocks, and bearings for the shaft;
and, external to the molded housing, a second ther-
mostatic metal spring fastened to the shaft exten-
sion and carrying the moving contact at its outer
end, the stationary contacts, and scales for setting
the stationary contacts at suitable positions for ob-
taining various time-overload operating curves un-
der specified operating conditions.
The external and internal thermostatic metal
springs have identical temperature-angular rota-
tion characteristics, and the external spring is
mounted so that its rotation is in the opposite
direction to that of the internal spring. Conse-
quently, a change in ambient temperature will not
produce an appreciable permanent change in the
position of the moving contacts, although the
All possible contingencies which may arise during installation, operation, or maintenance, and all details
and variations of this equipment do not purport to be covered by these instructions. If further information
is desired by purchaser regarding this particular installation, operation or maintenance of this equipment,
the local Asea Brown Boveri representative should be contacted.
A
llll
AIPP
Courtesy of NationalSwitchgear.com

Fig.
1
Type BL-1 Single Unit Relay without case (Front View)
2
Courtesy of NationalSwitchgear.com

I.L. 41-553.1G
Fig.
2
Type
BL-1
Double Unit Relay without case (Front View)
3
Courtesy of NationalSwitchgear.com

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Internal
Schematic
of
the
Type
BL
-
1
Double
Unit
Relay
,
with
Front
and
Back
Contacts
,
in
the
Type
FT
21
Case
.
Relays
with
Front
Contacts
Only
Have
the
Circuits
Associated
with
Terminals
2
and
3
Omitted
.
Fig
.
3
.
Internal
Schematic
of
the
Type
BL
-
1
Single
Unit
Relay
,
with
Front
and
Back
Contacts
,
in
the
Type
FT
21
Case
.
Relays
with
a
Front
Contact
Only
Have
the
Circuits
Associated
with
Terminals
2
and
3
Omitted
.
sulation
,
are
clamped
against
the
outer
surfaces
of
the
heaters
.
ceramic
insulation
,
heaters
,
and
heat
storage
discs
is
mounted
so
that
it
has
a
minimum
of
direct
con
-
tact
with
the
molded
housing
.
The
proportions
and
spacings
of
the
components
have
been
designed
to
provide
fast
operation
at
overloads
of
several
hun
-
dred
percent
or
higher
,
and
to
provide
long
operating
times
at
low
overloads
so
that
the
in
-
herent
thermal
capacity
present
in
the
usual
motor
design
can
be
full
utilized
.
A
high
permeability
reactor
is
provided
in
shunt
with
the
heaters
for
ac
application
.
This
reactor
has
no
effect
on
the
time
curve
of
the
relay
up
to
1000
%
of
pointer
setting
,
but
provides
additional
protection
for
extremely
high
currents
of
short
duration
.
The
reactor
should
be
removed
from
the
circuit
for
dc
application
.
This
is
readily
accomplished
by
removing
the
heavier
lead
from
the
two
left
hand
terminals
of
each
thermal
unit
.
enclosure
of
the
internal
spring
will
cause
it
to
res
-
pond
more
slowly
than
the
external
spring
and
a
temporary
change
in
contact
position
would
result
from
a
large
and
rapid
change
in
ambient
temperature
.
This
would
not
need
to
be
considered
in
normal
applications
,
however
.
This
assembly
of
spring
and
shaft
,
The
internal
spring
is
housed
within
ceramic
discs
having
high
thermal
-
shock
resistance
,
and
the
two
heater
elements
are
mounted
against
the
outer
surfaces
of
these
discs
.
The
outer
end
of
the
spring
is
held
fixed
by
a
notch
in
the
discs
.
Openings
in
the
centers
of
the
discs
expose
the
springs
to
the
heaters
with
only
air
separation
.
Thus
heat
is
transferred
to
the
spring
by
convec
-
tion
as
well
as
by
conduction
through
the
ceramic
,
and
(
particularly
at
high
overloads
)
by
radiation
also
.
The
heater
elements
are
connected
in
series
and
to
terminals
on
the
molded
housing
.
In
addi
-
tion
,
a
tap
on
each
element
is
connected
to
a
ter
-
minal
,
and
a
link
is
provided
by
which
the
two
tap
terminals
can
be
connected
together
and
thus
bypass
a
portion
of
each
heater
.
The
portions
of
the
heaters
remaining
in
the
circuit
have
a
larger
cross
section
also
,
so
that
they
will
withstand
the
same
percentage
overload
based
on
a
higher
full
load
current
.
The
contacts
are
silver
and
are
of
the
bridging
type
so
that
flexible
leads
are
unnecessary
.
The
moving
contact
consists
of
a
silver
plate
con
-
structed
so
that
it
can
pivot
on
its
mounting
and
be
self
-
aligning
with
the
stationary
contacts
.
The
stationary
make
contacts
are
supported
in
molded
insulation
fastened
to
a
plate
which
can
be
rotated
around
the
shaft
by
means
of
a
gear
sector
on
its
Metal
heat
storage
discs
,
with
intervening
in
-
4
Courtesy of NationalSwitchgear.com

I.L. 41-553.1G
edge and a pinion attached to the scale pointer.
This serves to expand the scales and permit in-
-creased accuracy of setting.
Stationary break contacts can be provided
when required. These are similar to the make con-
tacts and are mounted on a second rotatable plate
in front of the plate which supports the make con-
tacts. This plate is held in position by spring
pressure, but can be moved to any desired position
with reference to the make contacts. A scale on the
supporting plate for the make contacts is used in
locating the break contacts at a definite position.
Rotation of the make contacts by means of the
scale pointer does not change the spacing between
the make and the break contacts.
INSTANTANEOUS UNIT
This is a small solenoid type unit. A cylindrical
plunger moves up and down on a vertical guide
rod in the center of the solenoid coil. This guide
rod is fastened to the stationary core which in turn
screws into the element frame. A silver disc is
fastened to the moving plunger thru a helical
spring. When the coil is energized, the plunger
moves upward carrying the silver disc which
bridges three conical shaped stationary contacts.
After the contacts close the plunger moves slightly
farther before seating against the stationary core.
This assures positive contact pressure.
A Micarta disc on a threaded bushing is
assembled on the lower portion of the guide rod
and is locked in place by a nut. Its position deter-
mines the de-energized position of the plunger and
therefore the pickup current of the element, as in-
dicated by the graduated scale beside the disc.
OPERATION INDICATOR
The operation indicator is a small solenoid coil
connected in the trip circuit. When the coil is
energized, a spring-restrained armature releases
the white target which falls by gravity to indicate
the completion of the trip circuit. The indicator is
reset from outside the case by a push rod in the
cover or cover stud.
CONTACTOR SWITCH
The dc contactor switch in the relay is a small
solenoid type switch. A cylindrical plunger with a
silver disc mounted on its lower end moves in the
core of the solenoid. As the plunger travels up-
ward, the disc bridges three stationary contacts.
The coil is in series with the main contacts of the
relay and with the trip coil of the breaker. When
the relay contacts close, the coil becomes energized
and closes the switch contacts. This shunts the
main relay contacts, thereby relieving them of the
duty of carrying tripping current. These contacts
remain closed until the trip circuit is opened by the
auxiliary switch on the breaker.
CHARACTERISTICS
The type BL-1 relay is designed for use in
applications where the current transformer ratio is
such that with 100 percent of full load on the
protected machine the relay will receive a current
within the limits of 2.5 to 5.0 amperes. For full
load currents within the range, the relay can be set
to operate in accordance with the characteristic
curves shown in Figs. 5 and 6. Note that there are
three initial current conditions shown in each
figure:
O%, 70%, and 100% of pointer setting. The
curves are based upon having the initial current
maintained long enough for the moving contact to
stop moving. Then the current is increased to some
percent of pointer setting to obtain the operating
time.
Since an overload might occur at or shortly
after the time a motor is started, or after a motor
has reached a constant temperature rise while
carrying less than full load, Figs. 5 and 6 show how
the operating time will be affected for a zero initial
load and for a 70 percent initial load. As would be
expected, the operating time is somewhat longer
for these conditions, but the protected motor could
carry the overload longer before reaching a
dangerous temperature.
It will be observed that the curves for the 2.5
and the 3.5 ampere settings diverge somewhat as
the overload increases. The amount of divergence
will not seriously affect any application of the
relay. For full load current settings greater than
2.5 amperes but less than 3.5 amperes, the
operating time at any of the higher values of
overload can readily be obtained by interpolation.
5
Courtesy of NationalSwitchgear.com

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LOAD
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396065
FiQ
-
5
.
Current
-
Time
Curves
for
Normal
Appl
i
cations
of
the
Type
BL
-
1
Relay
Covering
Range
of
F
uff
-
Load
Currents
from
2.5
to
3.5
Amperes
,
Using
Pointer
Settings
marked
on
,
n
9
after
Steady
Full
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Load
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Shorting
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Dial
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60
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Time
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Delay
for
725
%
Load
Occurr
6
Courtesy of NationalSwitchgear.com

I
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.
41
-
553.1
G
100
90
TIME
CURVES
FOR
TYPE BL
-
1
RELAY
80
60
MIN
,
CURRENT
3
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APPLIED
AFTER
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REACHES
FINAL
POSITION
FOR
INITIAL
STEADY
LOAD
INDICATED
BELOW
.
ZERO
CURRENT
(
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APPROX
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100
200
300
400 500
600
700
800
900
1000
PERCENT
OF
POINTER
SETTING
Curve
396066
Current
-
Time
Curves
for
Normal
Applications
of
the
Type
BL
-
1
Relay
Covering
Range
of
Full
Load
Currents
from
3.75
to
5.0
Amperes
,
using
Pointer
Settings
marked
on
Dial
.
60
-
Minute
Time
-
Delay
for
725
%
Load
Occurr
-
ing
offer
Steady
Full
-
Load
.
Shorting
Link
Closed
.
Fig
.
6
.
7
Courtesy of NationalSwitchgear.com

100
m
90
u
TIME
CURVES
FOR
TYPE
BL
-
1
RELAY
15
MIN
.
CURRENT
80
-
x
-
70
60
50
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SETTING
FOR
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SETTING
WHEN
STARTING
FROM
100
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OF
FULL
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CURRENT
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1000
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1
r
100
200
300
400
500
600
700
800
900
1000
PERCENT
OF
FULL
-
LOAD
CURRENT
396063
Curve
Fig
.
7
.
Current
-
T
ime
Curves
for
Special
Applications
of
the
Type
BL
-
1
Relay
covering
Range
of
F
ull
-
Load
Currents
from
2.75
to
3.75
Amperes
.
Contact
Settings
Determined
by
Test
for
15
-
Minute
Delay
with
725
%
Load
Occurring
after
Moving
Contact
reaches
Final
Position
for
Steady
Full
-
Load
.
Shorting
Link
Open
.
8
Courtesy of NationalSwitchgear.com

I
.
L
.
41
-
553.1
G
Fig
.
8
.
C
urrent
-
Time
Corves
for
Special
Appl
ications
of
the
Type
BL
-
1
Relay
Covering
Range
of
Fufl
-
Load
Currents
from
4.0
to
5.0
Amperes
.
Contact
Settings
Determined
by
Test
for
15
-
Minute
Delay
with
125
%
Load
Occurring
after
Moving
Contact
reaches
Final
Position
for
Steady
Full
Load
.
Shorting
Link
Closed
.
9
Courtesy of NationalSwitchgear.com

Fig
.
9
.
Contact
-
Opening
and
Reset
Time
Curves
for
the
Type
BL
-
1
Reioy
for
Fult
-
Load
Settings
of
2.5
to
3.5
Amperes
os
marked
on
Dial
.
Shorting
Link
Open
.
10
Courtesy of NationalSwitchgear.com

I
.
L
.
41
-
553.1
G
Contact
-
Opening
and Reset
Time
Curves
for
the
Type
BL
-
1
Relay
for
Full
-
Load
Settings
of
3.75
to
5.0
Amperes
as
marked
on
Dial
,
Shorting
Link
Closed
.
Fig
.
10
.
11
Courtesy of NationalSwitchgear.com

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836
Fig
.
11
.
External
Schematic
of
the
Type
BL
-
I
Double
Unit
Relay
,
wifh
Front
and
Back
Contacts
in
the
Type
FT
21
Cose
.
significance
as
the
outer
scale
markings
which
are
used
for
the
full
heater
,
as
described
for
Fig
.
8
.
The
curves
for
Fig
.
6
are
for
the
3.75
and
5.0
ampere
settings
,
and
time
values
at
high
overloads
at
in
-
termediate
settings
can
be
obtained
by
interpola
-
tion
.
The
curves
of
Figs
.
5
and
6
will
be
found
to
be
very
nearly
identical
if
one
set
is
superimposed
on
the
other
.
The
entire
heaters
are
in
the
circuit
for
the
curves
of
Fig
.
5
.
The
outer
scale
markings
range
from
2.5
to
3.5
amperes
in
0.25
ampere
steps
,
and
when
the
scale
pointer
is
set
to
one
of
the
indicated
current
values
the
relay
contacts
will
close
in
ap
-
proximately
60
minutes
if
the
current
increases
to
125
percent
of
the
full
load
value
after
the
full
load
current
has
been
flowing
long
enough
for
the
temperature
rise
to
reach
a
constant
value
.
These
curves
represent
the
primary
performance
re
-
quirements
of
the
type
BL
-
1
relay
.
While
there
are
no
uniform
standards
for
the
overload
capacities
of
all
types
of
motors
,
these
relay
characteristics
will
permit
full
utilization
of
the
overload
capacity
of
most
motors
at
light
overloads
while
providing
rapid
operation
under
heavy
overloads
.
The
heater
element
will
not
be
injured
by
carrying
a
current
of
35
amperes
with
the
shorting
link
open
,
or
50
amperes
with
the
link
closed
,
for
a
length
of
time
sufficient
to
close
the
contacts
from
a
cold
start
with
the
pointer
set
at
3.5
to
5.0
amperes
respectively
.
One
-
second
ratings
for
the
heater
are
twenty
times
the
maximun
full
load
current
setting
for
the
open
and
closed
link
positions
,
or
70
and
100
amperes
respectively
.
On
ac
the
reactor
allows
the
above
ratings
I
2
t
(
702
x
1
sec
and
1002
x
1
sec
)
be
extrapolated
down
to
F
x
0.1
sec
.
For
the
curves
of
Fig
.
6
,
the
short
-
circuiting
link
is
closed
on
the
two
right
-
hand
terminals
,
thus
leaving
only
a
portion
of
each
heater
in
the
circuit
.
The
inner
scale
markings
,
which
range
from
3.75
to
5.0
amperes
in
0.25
ampere
steps
,
have
the
same
12
Courtesy of NationalSwitchgear.com

In certain applications it might be desirable to
have faster operation at high values of overload.
This can be accomplished by a change in the con-
tact setting, but the operating time at light
overloads will be reduced to a still greater extent
and thus the full overload capacity of the motor at
light overloads may be made unavailable. Fig. 7
shows time-overload characteristics for the limits
of the adjustment range when the short-circuiting
link is open and when the contact spacing has been
reduced so that the contacts will close in 15
minutes on an overload of 125 percent after cons-
tant temperature has been reached on full load.
For this combination of load and overload, at the
end of the 15-minute period the pointer should be
moved clockwise to a position where the contacts
just close. It will be possible to move the pointer
sufficiently beyond the 2.5 ampere point to obtain
a 15-minute setting for this value of full load, so
Fig. 7 shows 2.75 amperes as being one end of the
range for the accelerated operation. The upper end
of the range when the shorting link is not used has
been shown as 3.75 amperes, since the pointer
position for a 15-minute setting at 125 percent of a
3.75 ampere full load current will be near or
somewhat to the left of the 3.5 ampere scale mark-
ing.
It is not expected that these faster operating
curves will be used for general application. They
are presented to show how the relay characteristics
may be modified to meet special conditions. Since
the pointer position must be determined by test, it
could be located to give a time other than 15
minutes at 125 percent overload. If the time were
between 15 and 60 minutes, an approximate
operating curve could be estimated by interpola-
tion between Fig. 5 and 7.
Fig. 8 is similar to Fig. 7 but shows faster time-
overload curves for full load currents that require
the use of the shorting link.
It will be observed that the curves of Figs. 5
and 6 are approaching an asymptotic position at
125% of full load, and that the curves of Figs. 7
and 8 are farther from their asymptotic position at
125% of full load, as would be expected because of
the shorter time delay. Prior conditions of load
(between zero and full load) will not affect the
value of current that will ultimately close the relay
contacts, but variables such as friction and dis-
crepancies in calibration prevent precise location
of the asymptotic value. However, after making
some allowance for such variables, a value of 118%
of full load current can be considered as the max-
imum current that will not produce eventual clos-
ing of the relay contacts when settings are made as
described for Figs. 5 and 6. For settings made per
Figs. 7 and 8 this current value will be 110% of full
load.
Figs. 9 and 10 show resetting times for the type
BL-1 relay for the shorting link opened or closed.
The complete resetting time is considered to be the
time measured from the moment the relay current
is interrupted until the contacts return to the posi-
tion they would occupy for the steady state condi-
tion of 100 percent of full load current. This com-
plete time is composed of the time required for the
contacts to part and the time for them to travel
back to 100 percent position, and separate curves
are shown for these two components of the com-
plete time. The time will vary depending upon
whether the overload occurs after the motor has
been carrying 100 percent load or from a cold
start, and curves as shown for the two conditions.
The curves are shown for a relay setting at either
end of the adjustment range, and intermediate
values may be obtained by interpolation.
The ambient temperature compensation
provided in the type BL-1 relay causes its
operating time for a given current to remain ap-
proximately the same regardless of changes in the
ambient temperature at the relay. If the ambient
temperature at the motor location varies, the
motor of course will carry a higher overload safely
when the ambient temperature is low. However, a
replica type relay cannot respond to the ambient
temperature at the motor unless it has no ambient
temperature compensating means and unless it is
mounted either adjacent to the motor or, if at a
distance, in a location where there is assurance
that the ambient temperature will vary in exactly
the same way as at the motor. This condition fre-
quently cannot be met. Also, the relay temperature
at the operating point should be very close to that
of the motor at its maximum safe operating
temperature. The type BL-I relay was designed for
a minimum operating temperature much lower
than the safe operating temperature of a motor,
1313
I
.
L
.
41
-
553.1
G
Courtesy of NationalSwitchgear.com

but
with
a
similar
rate
of
rise
when
the
rise
is
ex
-
pressed
as
a
percentage
of
the
total
change
in
the
relay
temperature
.
This
was
done
to
obtain
a
low
relay
burden
and
to
increase
the
amount
of
overload
that
the
relay
can
carry
without
injury
.
With
the
low
operating
temperature
of
the
type
BL
-
1
relay
,
it
would
not
be
satisfactory
to
block
or
render
inoperative
the
ambient
temperature
com
-
pensation
,
as
even
moderate
changes
in
ambient
temperature
would
cause
appreciable
changes
in
the
relay
operating
time
.
Mount
the
relay
vertically
by
means
of
the
rear
mounting
stud
or
studs
for
the
type
FT
projection
case
or
by
means
of
the
four
mounting
holes
on
the
flange
for
the
semi
-
flush
type
FT
case
.
Either
the
stud
or
the
mounting
screws
may
be
utilized
for
grounding
the
relay
.
External
toothed
washers
are
provided
for
use
in
the
locations
shown
on
the
out
-
line
and
drilling
plan
to
facilitate
making
a
good
electrical
connection
between
the
relay
case
,
its
mounting
screws
or
studs
,
and
the
relay
panel
.
Ground
Wires
are
affixed
to
the
mounting
screws
or
studs
as
required
for
poorly
grounded
or
in
-
sulating
panels
.
Other
electrical
connections
may
be
made
directly
to
the
terminals
by
means
of
screws
for
steel
panel
mounting
or
to
the
terminal
stud
furnished
with
the
relay
for
thick
panel
moun
-
ting
.
The
terminal
stud
may
be
easily
removed
or
inserted
by
locking
two
nuts
on
the
stud
and
then
turning
the
proper
nut
with
a
wrench
.
The
instantaneous
unit
used
in
the
type
BL
-
1
relay
has
a
vertical
scale
graduated
from
6
to
50
amperes
.
The
scale
markings
indicate
the
pick
-
up
current
when
the
Micarta
disc
is
opposite
the
scale
division
and
when
the
element
is
in
correct
adjust
-
ment
.
The
operation
indicator
normally
supplied
in
the
type
BL
-
1
relay
will
pick
-
up
at
1.0
ampere
direct
current
.
For
detail
information
on
the
FT
case
refer
to
I
.
L
.
41
-
076
.
SETTINGS
CONTACT
RATINGS
There
are
two
settings
to
be
made
on
the
relay
.
They
are
as
follows
:
Control
Capacity
Will
Break
Control
Voltage
In
Amperes
Will
Close
Unit
1
.
INSTANTANEOUS
UNIT
Set
the
element
for
a
pick
-
up
current
slightly
above
the
maximum
current
which
the
apparatus
may
receive
in
normal
service
,
as
for
example
,
the
starting
current
of
motor
or
the
magnetizing
in
-
rush
current
of
a
transformer
.
This
setting
is
made
by
moving
the
Micarta
disc
to
a
point
opposite
the
desired
pick
-
up
current
value
indicated
on
graduated
scale
.
After
the
setting
is
made
lock
the
disc
in
place
by
means
of
the
locknuts
.
0.8
Heater
Heater
Heater
Instan
-
taneous
Instan
-
taneous
125
Vdc
250
Vdc
120
Vdc
3.0
t
0.6
3.0
t
5.0
5.0
t
125
Vdc
1.5
30.0
tt
120
Vdc
15.0
30.0
tt
t
These
values
apply
where
the
contactor
switch
is
not
used
to
seal
around
the
heater
unit
contact
or
contacts
.
For
tripping
duty
,
the
heater
unit
contacts
can
close
30
amperes
at
125
or
250
volts
dc
if
these
contacts
are
sealed
around
by
the
contactor
switch
.
2
.
HEATER
UNIT
For
the
usual
case
,
setting
the
thermal
element
involves
only
locating
the
scale
pointer
at
a
posi
-
tion
corresponding
to
the
full
load
secondary
current
of
the
protected
equipment
,
and
opening
or
closing
the
shorting
link
depending
upon
whether
the
pointer
is
being
set
in
accordance
with
the
up
-
per
or
the
lower
scale
markings
.
The
relay
then
will
have
the
characteristics
shown
in
Figs
.
5
or
6
.
This
method
of
setting
the
relay
for
various
full
load
currents
affords
greater
flexibility
in
applica
-
+
t
The
instantaneous
unit
contacts
will
carry
30
amperes
for
1
second
.
©
INSTALLATION
The
relays
should
be
mounted
on
switchboard
panels
or
their
equivalent
in
a
location
free
from
dirt
,
moisture
,
excessive
vibration
and
heat
.
14
Courtesy of NationalSwitchgear.com

TYPE BL-1 RELAY
LL. 41-553.2B
The vertical edge setting may be set for a larger
contact gap but should not be set for more than six
minor divisions if the break contacts are to be in a
closed position at full load.
External diagram in Fig. 9 show several com-
binations for applying these units.
ADJUSTMENT & MAINTENANCE
The proper adjustments to insure correct
operation of this relay have been made at the fac-
tory. Upon receipt of the relay no customer ad-
justments, other than those covered under
“SETTINGS” should be required.
ROUTINE MAINTENANCE
All relays should be inspected and checked
once a year or at other time intervals as dictated by
experience to assure proper operation. Generally a
visual inspection should call attention to any
noticeable changes. A minimum suggested check
on the relay system is to close the contacts manual-
ly to assure that the breaker trips and the target
drops. If an additional time check is desired, pass
test current through the relay and check the time
of operation.
All contacts should be periodically cleaned. A
contact burnisher #182A836HOl is recommended
for this purpose. The use of abrasive material for
cleaning contacts is not recommended, because of
the danger of embedding small particles in the face
of the soft silver and thus impairing the contact.
ACCEPTANCE CHECK AND
CALIBRATION
ICS ACCEPTANCE CHECK
Refer to test diagram shown in Fig. IO.
Connect an adjustable dc current source to relay
terminal 4 as shown with a jumper type connection
made inside the relay. Connect the jumper to the
right hand (facing the front of the relay) stationary
contact of the ICS located in the lower right posi-
tion.
Close switch
S1 and pass sufficient dc current
through the trip circuit to close the contacts of the
ICS. This value of current should not be greater
than the particular ICS nameplate rating. The in-
dicator target should drop freely.
Repeat above except to pass 85% of ICS
nameplate rating current. Contacts should not
pick up and target should not drop. Open switch
S1 when checking is completed.
ICS CALIBRATION
Use the following procedure for calibrating the
relay if the relay has been taken apart for repairs
or the adjustment have been disturbed. This
procedure should not be used unless it is apparent
that the relay is not in proper working order. (See
“Acceptance Check”).
Initially adjust unit on the pedestal so that ar-
mature lingers do not touch the yoke in the reset
position. This can be done by loosening the moun-
ting screw in the molded pedestal and moving the
ICS in the downward position.
1. Contact Wipe: Adjust the stationary con-
tacts so that both stationary contacts make
with the moving contacts simultaneously
and wipe
l/64” to 3/64” when the armature
is aganist the core.
For double trip type units, adjust the third
contact so that it makes with its stationary
contacts at the same time as the two main
contacts or up to
1/64” ahead.
2. Target: Manually raise the moving contacts
and check to see that the target drops at the
same time the contacts make or up to
1 / 16"
ahead. The cover may be removed and the
tab holding the target reformed slightly if
necessary. However, care should be exer-
cised so that the target will not drop due to a
slight jar.
3. Pickup: Unit should pickup at 98% of rating
and not pickup at 85% or rating. If
necessary the cover leaf springs may be ad-
justed. To lower the pickup current, use a
tweezer or similar tool and squeeze each
15
Courtesy of NationalSwitchgear.com

break contacts, and when closer settings are
desired they should be made by test.
ADJUSTMENTS AND MAINTENANCE
The proper adjustments to insure correct
operation of this relay have been made at the fac-
tory and should not be disturbed after receipt by
the customer. Contact or pickup settings must be
made as required by the application, but alteration
of assembly adjustments should be avoided. If the
adjustments have been changed, if the relay has
been taken apart for repairs, or if it is desired to
check the adjustments at regular maintenance
periods, instructions below should be followed.
All contacts should be cleaned periodically. A
contact burnisher S#182A836HOl is recommend-
ed for this purpose. The use of abrasive material
for cleaning contacts is not recommended, because
of the danger of embedding small particles in the
face of the soft silver and thus impairing the con-
tact.
INSTANTANEOUS UNIT
Remove the plunger core and see that the top
of the plunger is clean. Reassemble the plunger,
and adjust the position of the core screw so that
when the contacts are closed the plunger butts
against the stop with the spring half compressed.
With a
l/32 inch contact separation, the contacts
should pick-up at 6 amperes, 60 cycles. If the
plunger does not pickup and seal in at this current,
adjust the core screw so that it will and yet have
sufficient compression of the spring to prevent
sticking. Test for sticking after 50 amperes has
been passed through the coil.
OPERATION INDICATOR
Adjust the indicator to operate at 1.0 ampere
direct current gradually applied by loosening the
two screws on the under side of the assembly, and
moving the bracket forward or backward. If the
two helical springs which reset the armature are
replaced by new springs they should be weakened
slightly by stretching to obtain
calibration. The coil resistance is
0.16 ohm.
the 1 ampere
approximately
16
CONTACTOR SWITCH
Adjust the stationary core of the switch for a
clearance between the stationary core and the
moving core of
l/64” when the switch is picked
up. This can be done by turning the relay
up-side-
down or by disconnecting the switch and turning it
up-side-down. Then screw up the core screw until
the moving core starts rotating. Now, back off the
core screw until the moving core stops rotating.
This indicates the points where the play in the
assembly is taken up, and where the moving core
just separates from the stationary core screw. Back
off the core screw approximately one turn and lock
in place. This prevents the moving core from strik-
ing and sticking to the stationary core because of
residual magnetism. Adjust the contact clearance
for 3/32” by means of the two small nuts on either
side of the the Micarta disc. The switch should
pick up at 2 ampere dc. Test for sticking after 30
amperes have been passed through the coil.
HEATER UNIT
The assembly and adjustment of the thermal
unit requires alignment fixtures and other special
tools, as well as special test equipment for locating
the position of the compensating spring assembly
on the shaft and determining the calibration
points. Any dismantling or alteration of the ad-
justments should be avoided, as this may result in
excessive bearing friction or calibration errors.
However, the construction and overload capacity
of the thermal unit is such that very little
maintenance should be required.
The resistance of the heater and instantaneous
unit, measured at the case terminals, should be
0.25 ohm when the shorting link is open and 0.13
ohm when the link is closed.
The moving contact should rotate without
noticeable friction, and when displaced manually
and released it should return to its original posi-
tion. The shaft should have about 0.010 inch end
play.
If the calibration of the thermal unit is to be
checked at one or more points, the precautions
mentioned in previous sections should be observed.
Testing should be done with the relay in its case
Courtesy of NationalSwitchgear.com

I.L. 41-553.1G
and the cover in place, and preferably with the case
mounted on a swtichboard panel. If the relay time
is to be checked from a cold start, the relay should
have been de-energized for several hours
beforehand. If the overload is to be applied follow-
ing a constant load, the current must be main-
tained at the constant initial value until there is no
further change in the moving contact position
before applying the overload. Both the load and
overload currents must be carefully regulated
throughout the test. The relay should not be sub-
jected to drafts or sudden changes in temperature
during the test, as there is some delay in the
response of the temperature compensation. In the
factory calibration the relay is held in a controlled
temperature and other precautions are taken to
minimize factors which would introduce calibra-
tion errors.
The test current should be interrupted as soon
as the contacts close in order to avoid possible
damage to the heaters, particularly when testing at
high values of overload.
RENEWAL PARTS
Repair work can be done most satisfactorily at
the factory. However, interchangeable parts can be
furnished to the customers who are equipped for
doing repair work. Completely assembled and
calibrated thermal elements can be furnished, but
individual parts for the thermal element should not
be ordered since factory fixtures and equipment
are necessary for satisfactory assembly and
calibration. When ordering parts, always give the
complete nameplate data.
ENERGY REQUIREMENTS
The burdens of the heater unit plus the 6-50
ampere instantaneous unit in series at
5 amperes
60 cycles is as follows:
Heater
lap Llnk Continous
Position
Rating Amp Watt Volt-Amp power Factor
Open
3.5 6.25 6.25
1.0
Closed 5.0 3.25
3.25
1.0
17
Courtesy of NationalSwitchgear.com

.
563
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6.375
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PANEL
LOCATION
SEMI
-
FLUSH
MTG
,
PROJECTION
MTG
.
DIMENSIONS
IN
INCHES
DIMENSIONS
IN
MM
.
\
H
-
ARGE
INTERNAL
\
/
\
a
EXTERNAL
\
/
XjOOTH
WASHER
—
SMALL
EXTERNAL
TOOTHED
WASHERS
.
PANEL
CUTOUT
8
DRILLING
FOR
SEMI
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FLUSH
MTG
.
1
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2.688
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6
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.
397
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—
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*
1.031
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(
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(
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1
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-
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SCREW
.
375
1
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344
SPACERS
FOR
(
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PANELS
(
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R
PANEL
CASE
1
r
A
,
5
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-
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SCREW
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FOR
THICK
PANELS
USE
5
/
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-
18
STUDS
)
INTERNAL
-
EXTERNAL
TOOTHED
WASHERS
.
190
-
32
SCREW
FOR
THICK
PANELS
USE
.
190
-
32
STUDS
.
594
(
15.09
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1.0
(
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nt
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A
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1
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(
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•
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-
1.031
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1.031
(
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)
(
26.19
)
(
26.19
)
(
26.19
)
.
750
‘
—
TERMINAL
NUMBER
DIA
.
(
19.05
)
10
HOLES
OR
kl
.
031
CUTOUT
PANEL
DRILLING
OR
CUTOUT
FOR
PROJECTION
MTG
.
(
FRONT
VIEW
)
.
641
TERMINAL
AND
MOUNTING
DETAILS
OIA
;
(
16.28
)
57
D
7901
O
Fig
.
12
.
Outline
and
Drilling
Plan
for
the
BL
-
I
Relay
in
Type
FT
2
7
Case
.
18
Courtesy of NationalSwitchgear.com