What is a Soft Starter?
A Soft Starter is a device used to control the startup current of electric motors. As you may know, the startup current of electric motors is typically 5 to 8 times the motor’s rated current. This surge can cause significant voltage drops (depending on motor size) on the power grid connected to the motor, disrupting protective equipment and other devices on the same network.
Since electric motors draw high current during acceleration to nominal speed, a Soft Starter helps limit this surge—known as inrush current—and controls motor torque, resulting in safer, smoother, and gradual startups. Soft Starters protect motors from potential damage and extend system life by reducing heat from frequent start/stop cycles, mechanical stress, and electrodynamic strain on cables and shafts.

Key Features of XA3175 Soft Starters

Rated current: 23 to 1600 amps
Operating voltage: 380 to 690 VAC
Control supply voltage: 210 to 220 VAC
Dedicated Windows software for remote control (start, stop, reset, settings, etc.)
Built-in bypass contactor (23–1000A)
Adaptive acceleration control method (XLR8)
Torque and voltage ramp control for start/stop
24-hour programmable start/stop (timer, clock)
Two-phase control
Current range control
Kick Start function (initial torque boost)
Internal bypass circuit for energy saving and easy installation
Analog output (0–20 mA and 4–20 mA)
Detachable external keypad with IP65 protection
Electrical protections: phase reversal, overcurrent, undercurrent, current imbalance, overvoltage, undervoltage
Full motor protection: ground fault, rotor lock
Full thermal protection: RTD, PT100, PTC
MODBUS RTU protocol over RS485 for monitoring and remote control
Motor startup methods: In-line (3-wire) or Inside delta (6-wire)
Measurement counters: A, pf, kW, kVA
Simulation without startup (for fault testing, etc.)
Real-time logging and display of operational data and faults (99 events)
Easy programming and installation

Adaptive Acceleration Control (XLR8)
This feature, known as adaptive acceleration control, manages motor acceleration and deceleration profiles. In load-based acceleration control, the user only sets the ramp slope and time, and the Soft Starter intelligently analyzes the motor and connected load to apply optimal current, voltage, and torque for startup.
In essence, the Soft Starter monitors motor behavior during startup and stop phases and optimizes control to ensure smooth and improved transitions.

Built-in Bypass Contactor
The internal contactor supports currents from 23A to 1000A and performs approximately three times better than standard contactors. It offers 2.6× better heat dissipation, 25% improved safety, 20% energy savings, and a lifespan of around 100,000 startups.

Display
XA3175 Soft Starter displays feedback in plain language—no need to decode error codes. Motor performance tracking is simple, and the display logs 99 real-time operational and fault events with detailed timestamps.

Panel Door Display Installation
When multiple Soft Starters are installed in one panel, detachable displays can be mounted on the panel door for centralized and user-friendly control. Once installed, the protection level is IP65.

Internal Bypass
Note that the Soft Starter only controls the thyristors during startup and stop phases. Once the motor reaches nominal speed, the Soft Starter no longer affects motor operation and only monitors it.
Therefore, after motor startup, the Soft Starter should be bypassed to reduce wear—especially on thyristors. This process, known as bypassing, significantly reduces internal heat.

Keep in mind that some Soft Starter models do not have built-in bypass. In such cases, an external parallel contactor is used, activated by the Soft Starter once the motor reaches nominal current.