GE AKR-30 Series Maintenance Manual page 223

SECTION 1 0-Type SST Overcurrent Trip Device
The SST is a s o l i d-state, d i rect-acti n g , self-powered trip
device syste m . The S S T system consists of t h e SST pro­
grammer u n it, c u rrent sensors, a n d a flux sh ifter t r i p de­
57
vice . F i g . shows a block d i agram of t h e syste m .
1 0.1 PROG RAMMER UNIT
58
F i g . shows a typical S ST prog r a m m e r u n it . T h e pro­
g r a m m e r u n it provides the com parison basis for overcur­
rent detect i o n and d e l i vers t h e e n e rgy necessary to trip the
b reaker. I t contai n s the e lectronic c i rc u itry for t h e vari o u s
t r i p e l e m e nts. T h e i r associated p i c k u p a n d t i m e de lay ad­
j u st me nts (set- poi nts) are located on t h e face plate . De­
p e n d i ng on the applicat i o n , prog r a m m e r u n its may be
e q u i p pe d with various combi natio n s of Long Time, S hort
T i m e , I nstanta n e o u s and G ro u n d Fault t r i p e l e me n t s . See
7
Table for ava i l ab l e rat i n g s , setti ngs and t r i p c h aracteris­
tics. Adj ustme nts are made by removing t h e clear cover
over t h e face p late, u nscrewing ( c o u n te r- clockwise) t h e
set- point k n o b , m o v i n g the set-po i n t a l o n g the slot t o t h e
n e w sett i n g , and screwi ng the set- p o i n t k n o b i n . O n ce a l l
adjustme nts are made , i n stall t h e clear c o v e r to t h e face
p late .
The SST prog ram m e r u n its can be optionally eq u i p ped
w i t h trip i nd i c at o rs (targets ) . These are p o p - o u t , m e ­
c h a n ical ly-resettable p l u ng e rs located across the t o p o f
t h e prog rammer's front. U n its w i t h a g r o u n d f a u l t e l e ment
e m ploy t h ree target s : from left to right, t h e f i rst is for over­
l o a d , the second for s h o rt c i r c u i t (actu ated by the short t i m e
a n d i n stantaneous e l e ments) a n d t h e t h i rd f o r g r o u n d fault.
The latte r is om itted on u n its without g r o u n d fault.
Frame
Breaker
Size
Type
(Amperes)
AKR-30 800
AKR-50 1600
600, 800, 1 200, 1600
AKRT-50 2000
CD
@
Pickup tolerance is ±.. 9%
Pickup tolerance is ±.. 1 0%
TAB L E 7 SST TRIP CHARACTER I STICS
X • Trip Rating
in Amperes
Long Time
• Sensor Tap
( )
(D
- - - - - - - - - -
-
( )
Pick (•L)
Sensor
Ampere
Multiple
Taps
of X
100, 1 50 , 225, 300
- or -
300 , 400 , 600, 800
.6, .7, .8,
300, 400, 600, 800 .9, 1 .0 ,
- or - 1 . 1 ( X )
800, 1 200 ,
1 600, 2000
@
G)
8
t
�- - - - - -
FIG. 57 - SST B LOCK DIAGRAM
E a c h target pops out w h e n i ts associated trip e le me n t
ope rates to t r i p t h e b reaker. After a tri p , t h e popped target
m u st be reset by hand. However, neglecti ng to reset does
not affect normal operation of any t r i p e l e ment o r p revent
the breaker from being reclosed .
The prog r a m m e r u n i t is mou nted to t h e l ower right of the
breaker as shown i n Fig.
top of the prog r a m m e r , see Fig.
mou nted to the u n d e r s i d e of the breake r's front fra m e .
S ST PROGRAMMER ADJUSTMENT RANGE (Set Points)
Short Time
®
@
( )
Time Time
Pickup
Delay Delay
Multiple
Band Band
(Seconds) of L (Seconds)
3, 4 , 5,
6, 8, 1 0 ( L )
Maximum Maximum
-or-
0 . 35
22
lnt..rmed .
Intermed .
1 . 75, 2 ,
0 . 2 1
1 0
2 . 2 5 , 2 . 5 ,
Minimum Minimum
3 , 4 ( L )
4 0.095
Time delay shown a t 600% of long time pickup setting ( 6 L ) , a t lower limit of band.
Time delay shown at lower limit of band.
59.
The bracket attached to the
58 ,
engages with a bracket
GROUND FAULT
®
®
Instantaneous
@)
( ) ( )
Pickup Pickup
Multiple M ultiple
o f L of X
.4, .5, .6,
.8, 1 .0,
1.2 ( X )
4, 5, 6,
8, 1 0 , 12 ( L ) . 2 5 , . 3 , . 4 ,
. 5 , . 6 ,
. 7 ( X )
.2, .25, . 3 ,
.4, . 5 ,
.6 ( X )
OVERLOAD
I TARGET
I
I
I
I
I
SHORT
I
lciRCU I T
I TARGET
I
@
Time
Delay
Band
(Seconds)
Maximum
I
0 . 30
Intermed.
0 . 1 6 5
Minimum
0.065
45