Automationdirect.com Stellar SR44, User Manual

Page: 226 / 238

Appendix C: Technical Hints
Technical Hints
Category: General
No: 9 Subject: Start Time with "Auto Ramp"
When "Auto Ramp" is selected, the ramp time is an arbitrary number, with “1” being fastest up to “255” the slowest.
The unit will be accelerated to full speed by the microprocessor with a varying ramp profile while trying to keep the
start current to a minimum.
No:
8
Subject:
Soft-Starts
Soft-Starters reduce motor starting current at the expense of reducing starting torque and increasing start time.
No: 7 Subject: Contactors
Contactors marked (for example K1) on wiring diagrams are not included within the Soft Starters.
No:
6
Subject:
Sizing Starters
Starters may need to be de-rated for high start frequency, current, ambient temperature, altitude, or long starts.
No:
5
Subject:
Commissioning 1
It is a good idea to start by using one of the standard applications. (Refer to ‘Applications’ Menu Settings in Ch.5)
No: 4 Subject: Slip-Ring Motors 2
Slip rings may be shorted at partial voltage by forcing a user current limit at start,
and then using the current limit timeout flag to control K2 and hence the shorting contactor.
No:
3
Subject:
Slip-Ring Motors 1
When sizing a single stage of resistors for use with a Soft-Starter,
care must be taken to balance the standstill torque requirements against large slips at full voltage.
No:
2
Subject:
Kick Start
Kick start is not always suitable for use with rolling starts or very light loads.
No: 1 Subject: Motor Configuration
If the motor starts OK but stalls as soon as a load is applied, then check the configuration of the motor,
i.e., it may be that the motor is meant to be connected in delta but is actually connected in star (wye).
SR44 Series Soft Starter User Manual
1st Ed, Rev B 07/31/2019
C–2