LOW-VOLTAGE POWER 
CIRCU~T 
BREAKERS
-· 
TYPES 
. AK•SO, 
AK-100
; 
AKF-2C, 
AKF-
2D, 
AKF-2E 
OPERATION 
INTRODUCTION
. 
The 
instructions 
contained 
herein 
are 
intended to 
aid 
in 
the 
maintenance and 
repair 
of 
basic 
breakers 
and 
accessories 
for 
AK-50-75
-1
00  Low  Voltage 
Power 
Circuit 
Breakers. 
· 
The 
basic 
AK_.50, 
AK-75 
and
· AK- 100 
breaker 
designs 
have 
been 
expanded 
to 
include 
special 
designs 
for 
specific 
applications. 
These 
design 
extensions 
have 
caused 
variations 
in 
the nomen-
clature 
including 
the 
following: 
AK-2-50,  AK-2- 75 
or 
AK-2- 100  -
Basic 
standard 
design 
of 
breaker 
for 
stationary 
mounting 
or 
for 
drawout 
use 
in 
AKD type 
equipment. 
AK-2A- 50,  AK-2A-75, · AK-2A-100  - The 
A 
indicates 
it 
.has_mounting. 
features 
for 
AKD-5 type equipment. 
AK-2-50S,  AK-2-75S, AK-2-lOOS  -
The 
S 
indicates 
breaker 
is 
equipped with a quick-
close 
mechanism
· which 
provides 
closing 
times 
of 
approximately 5 
cycles 
(.08 seconds) 
.. 
.. 
AKU-2-50- -
The 
u. 
indicates 
an 
internal 
fuse 
breaker 
combination: 
AKF-2C,  AKF-2D,  AKF-2E . - Are 
fie
ld 
switches 
for 
use 
in
.controlling 
shunffields 
of 
synchronous 
m~tQ~s  and 
generators. 
. 
AK
-2-50H  -
.The 
H  Indicates  the  inter-
. 
rupting 
rating 
has 
-
been 
increased 
to  the 
75,000 
amp
. 
class.
.  ·  ,  _  · 
-
AK
- 2- 50C,-
AK~2
-7
5C-
:.. 
The  C indicates 
the 
interrupting 
rating 
has 
been 
increased 
to 
the 
rno,ooo 
amp. 
class
.  . 
AKT-2- 50  -
The
· T 
indicates 
incr~ased. · · 
continuous 
rating 
of 2000 
amps. 
AK-3-50, 
AK
-
3-75, 
AK-3-100  - The  3 
indicates 
the 
breaker 
ls 
equippe!i with the 
Power 
Sensor 
OVercurrent 
Trip 
Device. 
AK-2-
50X 
- -
The 
x· 
indicates 
the 
-
breaker 
has 
very 
special 
features 
or 
it 
"includes_ · 
two 
or 
more 
. 
of 
the 
design 
extensions 
previously 
described. 
- .-
When  contacting . 
the 
factory' 
it 
is 
important 
to 
furnish 
the 
complete 
nameplate
· information. 
MANUAL 
CLOSING 
For 
a 
description 
of  manual  closing, 
refer 
to 
the 
section 
of 
these 
instructions 
entitled 
CLOS
-
ING 
THE  BREAKER  -
MANUALLY 
OPERATED 
AK-50  and 
section 
entitled  AK-50-75" AND-100 
STORED  ENERGY 
MANUAL 
MECHANISM, 
both 
under 
OPERA TING 
MECHANISMS. 
-'"' 
o<:> 
a:<( 
1-1-
%-' 
oo 
u> 
4' 
G 
G 
,fl 
LE
GEND 
® • 
CLOSING 
MOTOR 
~ 
•  RELAY 
COIL 
,1, 
•  RELAY  CONTACT 
CLOSING 
1 
SWITCH 
1 
--
:
:-~J 
REMOTE 
CLOSE 
.x
. 
F&G 
• MECHANICALLY 
OPfRATED 
SWITQIES
. 
· + • 
NOR
MALLY  OPEN  SWITCH  CONTACTS 
I  • NORMALLY  CLOSED  SWITCH 
COffTAC_!S 
L  • 
AUXILIAAY 
SWITCH 
CONTACT 
SIMPLIFIED  ELEMENTARY 
DIAGRAM 
INTERNAL  WIRING 
AK_:50, 
75, 
AND 
100
· 
Fig;l. 
lOSING 
-
1 
l'l£
MOTE
" 
.r 
r 
SWITCH 
I T ' l
OSE 
I  •  I 
G 
h; 
E 
G 
" 
l 
LEGEND 
~C 
: 
~'fc,~l'i,\ 
ii
t~~ 
fo~lTACTS 
(  -
ANTI-PUMP 
A£lAT 
C<J,ITACTS 
r 
tG: 
~~/r,:ti~~~~Wc\O.,l~lt>f:S 
j  : 
~~~~1s?ct•r 
C
Oi
l 
~ 
=~'l::.W& 
i~'i.1.~ 
~TACT:, 
<j, 
-
t.ORMAllT 
OptN 
SWITCH 
CONTACTS 
'f' 
-
NORMAU.T 
ClOS(O 
SWITCH 
CONTACTS 
INT(~l~.lf
1
~GC~fi~nt~~~U:icR 
Fig. 
lA. 
w 
-,--
I 
:~
TR
IP 
I 
I 
' 
[. 
.. 
OIL . 
1
0