74 • Application diagrams
8.20 Inside Delta Configuration
8.20.1 General Information
When the AS
TAT-XT is installed Inside Delta, the individual phases of the ASTAT-XT are connected in series with the
individual motor windings (6 conductor connections as with the star-delta starter). The ASTAT-XT must only conduct
about 58 % (=1\√3) of the rated motor current. This allows the use of a significantly smaller ASTAT-XT.
Note that although when connected Inside Delta the current is reduced by 1.73 (√3), you should choose an ASTAT-
XT as if current is reduced only by 1.5. (1/1.5=0.667=67%)
For example:
For a motor with a rated current of 870A motor, a 950A starter will be selected to operate In-Line.
For Inside Delta ASTAT-XT, we calculate (870 x 67% = 580A) and select a 580A starter.
8.20.2 Notes on Inside Delta Connection
Inside Delta
requires 6-wires to the motor.
Wrong motor connection might cause serious damage to the motor windings.
When installing the ASTAT-XT Inside Delta it is highly recommended to use a contactor in series to the ASTAT-XT or
upstream (after motor protection) in order to avoid a damage to the motor if the ASTAT-XT short circuits.
The sinusoidal shape of the current might be imperfect. As a result, higher harmonic content is incurred (THD), which
may be twice the THD value as in the standard In-Line connection.
Motor heat may increase (due to the higher THD).
Phase sequence to the input of the ASTAT-XT (1L1, 3L2 & 5L3 terminals) must be correct. Otherwise, Phase
Sequence fault will trip the ASTAT-XT immediately.
Higher torque can not be obtained.
The following factory preset features and functions are not active when Inside Delta mode is configured:
Kickstart
Soft Start Curve selection (Soft Start Curve 0 !! only).
Energy Saving and Slow Speed TRQ. (energy save and slow speed)
Phase Sequence in OFF mode
Note :
For a high starting torque process, it is recommended to use the ASTAT-XT in the In Line connection.
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