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tiastar™ Motor Control Centers Instruction Manual Maintenance
Figure 70: The stab assembly
5.10 Terminals and
internal conductors
Replace all damaged parts which show evidence of
discoloration, melting, or arcing damage.
5.10.1 Motor starter
1. Contactor – Replace the contacts and contact
springs if the contacts are welded or show heat
damage, displacement of metal, evidence of
binding in the guides, or wear in excess of wear
allowance. If deterioration extends beyond the
contacts,replace the contactor. Examples of such
deterioration include evidence of arcing on the
contactor moldings and insulation damage. Arc
chutes must be in place and secured prior to
operating contactor.
2. Overload relays – a) Any indication of an arc
striking or burning the overload relay may
require replacement. b) Contact operation
must be verified by electrically or mechanically
tripping and resetting the relay even if there
is no visual indication of damage that would
require replacement.
3. Fuses – Always replace all three fuses even
though only one or two are open circuited since
internal damage suffered by fuses not replaced
could result in nuisance shut down later.
4. Perform the pre-energization checks procedures
detailed on page 29 herein, before restoring
the equipment to service.
40
5.11 Adjustment of ETI
instantaneous trip motor
circuit interrupter (1A-125 A)
Hazardous voltage.
Will cause death or serious
personal injury.
Disconnect and lock-out all power
and control voltage sources supplying
the motor circuit interrupter before
adjusting trip setting or performing
any other maintenance operations.
ETI instantaneous trip motor circuit interrupters are
supplied as standard with Size 1 through Size 6
motor starters. The motor circuit interrupter
continuous current rating should not be less than
115% of motor full load current (MFLC). The MFLC is
obtained from the motor nameplate or from Table
430-150 of the NEC (1999). Use the following
procedure to adjust the instantaneous trip setting.
1. Move the operating handle to the "OFF" position
and open the unit door.
2. The instantaneous trip circuit breaker is factory
set at the LOW position.
To set: determine motor full load current from
the motor nameplate. Refer to the table and
determine the recommended setting position. Use
a screwdriver to set the indicator on the adjustment
screw to the appropriate position.
For maximum protection the trip position should be
set as low as possible. Turn the adjustment screw
counterclockwise to successively lower positions
until the breaker trips on motor starting.
After this position is determined, turn the
adjustment screw clockwise to the next higher
setting for normal operation. The adjustment screw
is infinitely adjustable for customer convenience.
If the breaker does not trip at the lowest setting
leave the indicator at this setting.
3. Adjust the trip setting by rotating the adjustment
dial to the position selected in step 2 above.
Ensure that the setting on a magnetic only motor
circuit protector does not exceed the maximum
allowable setting as defined in the 1999 National
Electrical Code, section 430-S2 (C)(3).
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