VFD vs Soft Starter: Which Do You Need? (Differences, Cost, Uses)

A soft starter only eases the motor up to full speed and then runs it at fixed speed; a VFD (variable frequency drive) controls the speed the whole time. Choose a soft starter to cut starting current on a fixed-speed machine, and a VFD when you need speed control or energy saving. Delta VFDs on Voltkart start at ₹7,380.

By Team Voltkart · Reviewed by Amit, Voltkart · Last updated 6 October 2026 · Prices checked 6 October 2026

VFD vs soft starter at a glance

What is the difference between a VFD and a soft starter?

A soft starter is a starting device. It places back-to-back thyristors in the motor supply and gradually increases the voltage, so the motor accelerates smoothly and the inrush current and mechanical shock of a direct-on-line start are reduced. Once the motor reaches full speed, many soft starters close an internal or external bypass contactor and the motor runs on the mains like any DOL motor; the soft starter has no further control over speed. A VFD is a speed controller. It converts the incoming AC to DC and then builds a new three-phase output whose frequency and voltage it controls continuously. Because frequency sets motor speed, the VFD can start the motor gently, run it at any speed the process needs, and stop it under control. The practical difference is simple: a soft starter solves a starting problem, a VFD solves a speed problem, and it solves the starting problem at the same time.

When should you use a soft starter?

A soft starter makes sense when the motor must always run at full speed and the only issue is the start: high inrush current that dips the supply or trips the breaker, belt slip, water hammer when a pump starts or stops, or mechanical shock on couplings and gearboxes. Typical examples are fixed-speed conveyors, crushers that start unloaded, compressors and large fans that always run flat out. It is usually cheaper than a VFD at the same rating, smaller, and adds almost no losses once bypassed. It does not save running energy, though, and its reduced starting torque can be a problem on loads that must start under heavy load. Voltkart does not stock soft starters; if a soft start is all you need, a star-delta starter built from contactors and a timer is the common lower-cost alternative for delta-rated motors (see motor starting methods).

When should you use a VFD?

Use a VFD whenever the process benefits from changing speed: pumps that must hold a pressure or flow, fans and blowers controlled by temperature or airflow, conveyors that must match a production rate, mixers, extruders and machine spindles. On centrifugal pumps and fans the saving can be large because the power drawn falls roughly with the cube of speed; running a fan at 80% speed needs only about half the power of full speed. A VFD also gives the softest possible start, with starting current close to the motor's full-load current and full torque from low speed, so it suits loads that must start under load. The trade-offs are higher cost, heat that must be removed from the panel, and harmonics that need the wiring and filtering the manual specifies. For a single-phase site, a single-phase input VFD can run a three-phase 230 V motor, which a soft starter cannot do.

Delta VFD prices (incl. GST)

Full model details are in the VFD price list and the AC drives range. Not sure of the size? Use the free motor starter & VFD calculator or read how to size a VFD.

Is a VFD better than a soft starter?

Not always; it depends on whether you need speed control. If the motor will always run at full speed, a soft starter (or a star-delta starter) does the starting job for less money and with less heat and complexity. If the motor drives a pump or fan that could run slower for much of the day, or the machine needs adjustable speed, the VFD is better and its energy saving can pay for the difference. A VFD is also the better choice when the load must start with high torque, because a soft starter reduces torque along with voltage. Compare drive brands in Delta vs Schneider VFD and the basics in AC drive vs VFD.

Why buy from Voltkart

• Genuine Delta drives and genuine Schneider contactors, overload relays and MPCBs from stock, with a GST invoice on every order.
• Authorised distributor of Selec and EAPL (star-delta timers) and Minilec (single-phase preventors).
• Pan-India dispatch; typically 2–3 days to Delhi NCR, UP and Haryana and 5–6 days elsewhere.
• Send the motor nameplate on WhatsApp +91 8800754881 (Mon–Sat, 12:30–7 pm) and we will suggest the starter or drive.

Frequently asked questions

Can a VFD be used as a soft starter?

Yes. Set the acceleration and deceleration times and the VFD starts and stops the motor smoothly with low current. It costs more than a soft starter, but adds speed control and energy saving.

Which saves more energy, VFD or soft starter?

The VFD. A soft starter only reduces stress during starting and then runs the motor at full speed. A VFD saves energy whenever the load can run slower, especially on pumps and fans.

What is the starting current with a soft starter and a VFD?

A soft starter typically limits starting current to about 2 to 4 times full-load current, depending on the setting and load. A VFD starts with current close to the motor full-load current.

Does Voltkart sell soft starters?

No. Voltkart stocks genuine Delta VFDs, and contactors, overload relays and star-delta timers for star-delta starters. WhatsApp 8800754881 if you are unsure which suits your motor.

Can a soft starter run a three-phase motor on single-phase supply?

No. Only a VFD with single-phase input can run a three-phase 230 V motor from a single-phase supply.