Chokes for Frequency Converters: Reliable Protection for the Mains and Electric Motors

Installing a frequency converter (VFD) is the right step toward automation and energy savings. However, the inverter itself is a source of high-frequency interference and can suffer from power grid instability. To protect expensive electronics, extend the service life of motor insulation, and avoid emergency shutdowns, it is necessary to use industrial chokes (reactors).

In the "ASD ELECTRONICS" online store, you can buy line and motor chokes for electric drives of any power capacity. We offer reliable components that will ensure the uninterrupted operation of your equipment even in the harshest industrial conditions.

Two Main Types of Chokes: What is the Difference?

When designing or repairing electric drive systems, it is important to clearly understand the difference between input and output reactors. They perform different tasks and are installed in different parts of the circuit.

1. Line (Input) Chokes / Reactors

These are installed between the power supply network and the frequency converter. Their main task is to work as a two-way shock-absorbing filter:

• Protecting the VFD from the grid: They smooth out sharp voltage spikes (for example, when powerful neighboring equipment on the line is turned on), preventing the breakdown of rectifier diodes and "Overvoltage" errors.
• Protecting the grid from the VFD: They reduce the level of higher harmonics (THDi) generated by the inverter. This protects transformers from overheating and sensitive automation (PLCs, sensors) from false triggering.

2. Motor (Output) Chokes / Reactors

These are installed between the frequency converter and the electric motor. They are necessary to protect the windings of the motor itself:

• Limiting peak overvoltages (dV/dt): A VFD outputs voltage in the form of rectangular pulses (PWM), which destroys cable insulation and motor windings. A motor choke smooths these pulses, bringing the current shape closer to a sine wave.
• Compensation of capacitive currents: Installing an output reactor is strictly mandatory if the cable length from the VFD to the motor exceeds 30–50 meters. Without it, the motor will begin to heat up severely and quickly fail.
• Noise reduction: They significantly reduce the characteristic high-frequency "squealing" noise of the electric motor when operating from a VFD.

How to Choose the Right Choke?

To ensure the device performs its functions correctly and does not become a bottleneck in the system, you need to pay attention to the following parameters when selecting:

1. Nominal operating current (A): The choke current must be equal to or slightly exceed the maximum current of the frequency converter (for a line choke) or the electric motor current (for a motor choke).
2. Inductance and voltage drop: A voltage drop of 2-4% is considered standard for industrial networks.
3. Operating voltage and number of phases: We supply chokes for standard three-phase (380V) and single-phase (220V) networks.

Why Buy Chokes from "ASD ELECTRONICS"?

Saving money on a reactor often leads to replacing a burnt-out VFD or rewinding the electric motor. Trust the selection of protective equipment to professionals:

• Free calculation and selection: Our engineers will help you select line and motor chokes taking into account the power of your VFD, cable route length, and load specifics.
• Items in stock: We keep popular ratings of input and output chokes in our warehouse for prompt shipment.
• Quality guarantee: We supply only certified products from trusted power electronics manufacturers.
• Competitive prices: We work without unnecessary intermediaries, offering optimal pricing for both retail and wholesale B2B clients.

Ensure long and safe operation for your equipment. Check out the choke catalog on our website or leave a request — we will quickly select the right model and arrange delivery throughout Ukraine!