Frame Size; Operation; Fused/Non-Fused - GE AKR-30 Series Maintenance Manual

SECTION 2-General Description
Type AKA low-voltage power c i rc u it breakers are used
for contro l l i n g and protecti n g power c ircuits in the l ow­
voltage range (usually up to 600 volts). I n serving this
function, they are a means of safely switching loads and
automatically cleari ng circuits when abnormal conditions
occur. Among these conditions, the more com mon are
short circu its and sustained overloads and under voltages.
The type AKA breakers are of the "quick-make, quick­
break description, having the feature of storing energy in a
closing spring for quick release in closi ng. I n closing, some
energy is transferred to an opening spring to be used
subsequently for fast tripping.
Knowledge of how the breaker is designed and how it
operates will enable the owner to make p ro per use of the
b reaker and to avoid m istakes in its o pe ratio n . S pecific
d i rections on adjust ments and mai ntenance p rocedu res
will be treated later.
The three main functional com pone nts of a b reaker are
its mechanism, an assembly comprising the conductive
members, and the i nterrupter.
The mechanism unit is designed to receive energy, store
it, and later (when called upon to do so) deliver it to close
c
the breaker1 contacts. It must be able to reverse its com­
mitment to lose the breaker at any point upon the activa­
tion of an automatic trip device ( i . e . , be "Trip- Free"). Fi­
nally, it also must be able to trip open a closed breaker
qu ickly enough to minimize arc erosion and in such a
manner as to effect proper arc transfer to the arc runner.
The cu rrent-carrying members of the breaker are as­
sembled on the back frame, which provides the mechani­
cal support req uired and also the insu lating structure
needed. The conductive members are the studs for exter­
nal connections, movable and stationary contact sets,
pivots for the movable contacts, and provision for mo unting
the cu rrent transformers.
The interrupter components are , in addition to the arcing
contacts, the arc ru n ners mounted on the back base and
the removable arc quencher assemblies.
I n addition to these basic components, a breaker may be
equipped with any combination of many accessories and
interlocking devices . Breakers may also differ in a variety
of areas as shown in Table 1 . A brief description of these
areas is given below.
M
outline d rawir;Jg is available for each breaker frame size
showing critical dimensions. The d rawing number appears on
the breaker nameplate and can be obtained from GE.
2 . 1 FRAME S IZ E
The breakers are available i n 5 frame sizes -
am peres A.C. (AKA 3 0/3 0 H , 30L, AKAU 30), 1 600
a m peres A . C . (AKA 50/5 0 H , AKAU 500), 2000 am­
peres A . C . (AKAT 5 0/50H), 800 a mperes D . C . (AKA
30) a n d 2000 am peres D . C. (AKA 50).
6
FIG . 1 - Manually Operated AKR-4A-50-1
These values represent the maxi m u m conti n uous cur­
rent capability of the respective frames . However, each
breaker carries a specific rating which is determi ned by the
c urrent sensor ampere rating or maxim u m setting of the
trip device with which it is equip ped .
2.2 OP ERATION
There are Manual and Electrical breaker models. The
Manual breaker, shown in Fig. 1 , has an operating handle
which is used to manually charge the mechanism closing
spri ng.
The Electric breaker, shown i n Fig. 2, contains an elec­
tric motor which charges the mechanism closing spri ng.
External control power is required to energize this motor
and its control circuit. A nameplate i ndicates what voltage
is req uired by the motor circuit and trip and close coils.
2.3 FUSED/NON FUSED
Fused breakers are identified as either AKAU 30 (800
ampere frame size) or AKAU 50 ( 1 600 am pere frame size) .
BOO
A fused breaker is shown i n Fig. 3. They are not inter­
changeable with Non- Fused breakers, si nce they require
deeper compartments for their fuses .