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

SECTION 2-General Description
Type AKR low-voltage power circuit breakers are used
for controlling and protecting power circuits in the low­
voltage range (usually up to 600 volts).
function, they are a means of safely switching loads and
automatically clearing circuits when abnormal conditions
occur. Among these conditions, the more common are
short circuits and sustained overloads and under voltages.
The type AKR breakers are of the "quick-make, quick·
break description, having the feature of storing energy in a
closing spring for quick release in closing. In 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 proper use of the
breaker and to avoid mistakes in Its operation. Specific
directions on adjustments and maintenance procedures
will be treated later.
The three main functional components of a breaker are
its mechanism, an assembly comprising the conductive
members, and the interrupter.
The mechanism unit is designed to receive energy, store
it, and later (when called upon to do so) deliver it to close
the breaker's contacts. It must be able to reverse its com­
mitment to close 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
quickly enough to minimize arc erosion and in such a
manner as to effect proper arc transfer to the arc runner.
The current-carrying members of the breaker are as·
sembled on the back frame, which provides the mechani­
cal support required and also the insulating 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 mounting
the current transformers.
The interrupter components are, in addition to the arcing
contacts, the arc runners mounted on the back base and
the removable arc quencher assemblies.
In addit1on to these basic components, a breaker may be
equipped with any combination of many accessones and
interlockmg dev1ces. Breakers may also d1ffer m a vanety
of areas as shown in Table
areas is g1ven below.
2.1

FRAME SIZE

The breakers are ava1lable 1n
peres
A.C. (AKA 30'30H, AKAU 30). 1 600
(AKA SO:SOH, AKAU 50), 2000
amperes
50/SOH). 800 D.C. (AKA 30)
D.C. (AKA 50).
6
In serving this
bnef descnpllon of these
1 . A
-
frame s1zes
5 800
amperes
amperes
AC (AKAT
and amperes
2000
FIG. 1 Manually Operated AKR-4A-50-1
-
These values represent the maximum continuous cur­
rent capability of the respective frames. However, each
breaker carries a specific rating which is determined by the
current sensor ampere rating or top setting of the trip
device with which it is equipped.
2. 2

OPERATION

There are Manual and Electrical breaker models. The
Manual breaker, shown in Fig.
which is used to manually charge the mechanism closing
spring.
The Electric breaker, shown in Fig. 2, contains an elec­
tric motor which charges the mechanism closing spring.
External control power is required to energize this motor
and its control c�rcuit.
IS required by the motor circuit.
2.3
FUSED/NON FUSED
am­
Fused breakers are identified as either
A.C.
ampere frame SIZe) or
A
fused breaker IS shown in Fig.
changeable with Non-Fused breakers, since they require
deeper compartments for their fuses.
has a n operating handle
1 ,
nameplate md1cates what voltage
A
AKRU 3 0 (800
ampere frame size).
AKRU 50 (1 600
They are not inter·
3.