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Commissioning
26 Digistart IS User Guide
www.controltechniques.com Issue: 4
Inside delta installation, non-bypassed
Figure 4-14 Power connections - inside delta installation, non-bypassed
Semiconductor fuses
(optional)
4.4 Fuse information
4.4.1 Power supply fuses
Semiconductor fuses can be used for Type 2 coordination (according to IEC 60947-4-2 standard) and to reduce the risk of damage
to SCRs from transient overload currents.
HRC fuses (such as Ferraz AJT fuses) can be used for Type 1 coordination according to IEC 60947-4-2 standard.
Fuses are not delivered with Digistart IS soft starters.
Adaptive Control controls the motor's speed profile, within the programmed time limit. This may result in a higher level
of current than traditional control methods.
For applications using Adaptive Control to soft stop the motor with stop times greater than 30 seconds, motor branch protection
should be selected as follows:
standard HRC line fuses: minimum 150% motor full load current
motor rated line fuses: minimum rating 100/150% motor full load current
motor control circuit breaker minimum long time setting: 150% motor full load current,
motor control circuit breaker minimum short time setting: 400% motor full load current for 30 seconds
Fuse selection is based on a 400% FLC start for 20 seconds in conjunction with standard published starts per hour,
duty cycle, 40°C ambient temperature and up to 1000 m altitude. For installations operating outside these conditions,
consult your local supplier.
These fuse tables contain recommendations only. Always consult your local supplier to confirm the selection for your
particular application.
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