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TYPE
& RANGE:
"KEI" type "SD" Star delta starter
and "AT" Auto Transformer are oil immersed Starters described
in this leaflet which are designed for starting of Sq. Cage motors between
41 HP to 100 HP where it is found necessary to minimise the starting current
and attain a higher Torque. The starter reduces the line voltage by means
of auto transformer and reduces proportionately line current taken by the
motor during starting or by star delta starting. The unit is suitable for
AC 3 phase,415v +6%,50 c/s supply and complies fully with BS 587-1957 and
IS 8544/1961.These starters are must where electricity boards are limiting
the use of direct on line starters beyond certain range. ENCLOSURE:
Compact, totally enclosed dust
proof and splash proof metal clad box with gas ketteds joints arranged for floor mounting with standard
finish of dark admiral gray paint. AT type and wall pedestal mounting with standard finish of dark admiral
gray paint. AT and SD type units are housed with triple pole-oil immersed manually
operated starting switch and auto transformer with hand tribbing provision
for instantaneous tripping by provided on side and SD type units are housed
with. PROTECTIONS:
(a) Overboard protection is through a triple pole series operated electromagnetic
overboard coils suitably time lagged with oil dashpots operated directly
on mechanism tripping the unit on sustained overloads .Suitable range of
calibration is also provided for thus ensuring more accurate fool-proof
overload protection.
(b) Under voltage protection: Electromagnetic
under-voltage protection is given by no volt coil fitted separately and acts
directly on the mechanism. The normal coil voltage is 415V,50Hz AC.
However
,coil suitable for other AC voltages such as 220V,110V and 550Volts can
be provided .If desired for remote control, a push button switch may connected
in series with removable tips. CONTACTS:
The starter is provided with
substantial size cross section made of electrolytic 99.9% purity copper
that have durable sliver plating on it It has easily replaceable fixed contacts
and the moving contacts are of self aligning controller type with removable
tips. COMMON SPECIAL FEATURES FOR AUTO-TRANSFORMER
STARTER AND STAR DELTA STARTER:
1. Correct sequence
device in the Star/delta units rendering it impossible to put the handle
into the ‘DELTA-RUN’ position without going through the ‘Star-Start’ position.
2. A suitable earthing terminal
is provided for connection to the earthing pad.
3. Remote stopping is possibly
by push button station or any other tripping device for which the same
has to be connected in series with n\v coil lead. Also for instantaneous
tripping an "OFF" lever is provided on the side of the starter
which trips the units at once in emergency.
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4. All MS spares and hardware are either painted or suitably electroplated
to prevent any rusting even if the unit is kept for a long time without
use.
5. parts subject to wear such
as contact are readily accessible for purpose of inspection ,maintenance
and renewal.
6. Interchangeability of some
of the spares with lower HP and Higher HP starter is assured.
7. (a) Intermittent class
of duty as per IS 8544 : 1967 is AC3 (b)
Number of load operation per hour is 2
8.
We can also provide extra accessories like Ammeter, Voltmeter, Cable Box,
Single Phasing Preventor, Pedestals etc.
SPECIAL FEATURES
FOR AUTO TRANSFORMER STARTER:
1. The auto transformers
provided on each starters on each starters are provided with standard
tappings for40%, 50% ,60% and 80% of the line voltage to be applied to
the motor while starting. Other percentage of tapping can be supplied
on special request instead of the above tappings. The tappings are all
brought out on the terminal board for easy accessibility and change if
required.
2. The starter and
auto transformer are enclosed in separate enclosure and are internally connected
with suitable wire bars. The oil chambers are provided separately just because the carbonised oil of the
starters do not make any deposition
on transformer thus electrical breakdowns in transformers insulation is
prevented completely. All ‘AT’ Starters leaving our works are having secondary
connection of 60% tappings. If the motor does not develop the required
starting torque the voltage can be changed by suitably changing tappings
on the secondary of the auto transformer.
OPERATION OF AUTO
TRANSFORMER AND STAR DELTA STARTER
(a) Check KW/HP of motor
and the starter which should match and should be identical.
(b) Usually the equipments is supplied without oil and hence fill oil
before energising the unit .Also fill dashpots which is supplied with
starter in separate bottle.
(C) Check all electrical connections.
(d) while starting press the lever provided on the left hand side of the
starter ,bring the handle to "START" position allow motor to
pick up speed and then changeover the handle to "RUN" position
i.e ,Delta position.
10. While ordering
please inform the following detail of motor :
(a)
Rated output in KW/HP.
(b) Full load Amps.
(c) UVR Coil voltage required.
(d) number of starts per hour required.
(e) Any extra accessories like Ammeter, Voltmeter, cable box ,single
phasing preventor ,pedestals etc. required.
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