It really depends on what you want to do, what results you want to see.
Strictly speaking, to get a current limit, you need to have a feedback regime. Constant voltage, voltage profiles etc and pseudo constant current devices and do not respond well to changing conditions.
There are essentially three levels,
- pseudo current limit
- current limit
- controled current
If we look at each of these:
Pseudo Current Limit. Essentially an open loop controller with a voltage ramp profile designed to emulate the approximate shape of the start voltage under a current limit start. The profile has a voltage plateau at part voltage for a programmable period of time and then the voltage increases to full voltage. Being an open loop contoller, the starter is less responsive to variations in starting conditions. It could hold the voltage low for longer than required, or elevate the voltage before the motor has reached full speed, causing a high start current.
Current Limit Essentially a Timed Voltage Ramp soft starter with a means of monitoring the current and freezing the ramp. If the current goes too high, the starter does nothing about it. Some implementations have a limit on how long they can freeze the ramp with a step to full voltage at the end of the period. Typically, these starters only monitor one phase current so can be fooled by supply problems etc.
Controlled Curent These starters monitor the current on all three phases (can be achieved by using two CTs in a three wire installation) and adjust the output voltage to achieve the required output current. Totally responsive to changes in loading, the ouptut voltage can go up or down. A constant current or a current ramp or a pre programmed current profile can be implemented.
The controlled current starter is able to accelerate the motor to full speed in the minimum time without exceeding a predetermined current. It is also able to have different profiles to accomodate different load types or variable start torque requirements. It is generally the most expensive system.
The open loop systems will eventually get to full voltage (just like a star / delta) and so are more impervious to incorrect setups, but the start current can be much higher than with the controlled current starter.
In a nutshell, I would say that the controlled current starter can provide shorter start times and lower start currents than the open loop types.
Best regards