Energy Technology

Power resistors for wind turbines, photovoltaics, power plants, and grid technology

Power resistors for wind turbines

A key focus in wind energy utilization is the reduction of the Cost of Energy. We support our customers in achieving this goal with robust, economical, and application-specific resistor solutions.

Thanks to a modular design approach, we can flexibly meet nearly all customer requirements regarding protection class, dimensioning, and mounting method – and supply even high-power devices at economically favorable conditions.

Chopper resistors for LVRT operation

Wind turbines must continue operating reliably even during short-term grid faults. This is where FRT resistors – also known as chopper resistors for LVRT operation – come into play. These power resistors ensure that wind turbines can absorb energy in a controlled manner in the event of a fault without destabilizing the grid.

FRIZLEN offers custom-designed chopper resistors specifically for LVRT (Low Voltage Ride Through) applications, capable of handling extremely high energy densities in very compact spaces. A typical scenario: during a short voltage dip, the wind turbine does not feed energy back into the grid but instead diverts it into the chopper resistor. This prevents generator overload and ensures compliance with grid requirements.

Our solutions are often based on compact steel grid resistors with robust 3-mm resistor elements – specifically designed for tight installation spaces. With decades of experience, high in-house manufacturing depth, and advanced simulation technologies, we offer project-specific designs with defined energy absorption capacity, protection ratings, and connection options.

This makes your chopper resistor a reliable component in LVRT operation – and keeps your wind turbine online even in even in case of disturbances.

[Translate to English:] LVRT-Widerstand IP00

Series T600 | FKEY

Steel grid fixed resistor with IP00 protection, designed for high energy absorption.

Braking resistors for pitch systems in wind turbines

In the pitch systems of modern wind turbines, reliable braking resistors play a key role in ensuring operational and failure safety. They ensure that excess braking energy is safely dissipated during active rotor blade adjustment.

FRIZLEN uses encapsulated flat resistors in compact designs, specifically developed to meet the demanding requirements of pitch applications. These resistors are designed to handle short-term load peaks with high energy levels and reliably perform even under challenging conditions such as temperature fluctuations, vibration, or humidity.

Their robust design and high protection rating make them ideal for use in the hub area or within blade control enclosures.

A key advantage of this design is the combined ability to absorb energy while providing protection in case of a fault: In the event of a shorted chopper transistor causing uncontrolled feed-in from the frequency converter, the resistors remain intrinsically safe by internally burning out. This supports the safety requirements of critical pitch systems.

The thermal design is tailored to the specific requirements of each turbine type – individually calculated, tested, and manufactured.

[Translate to English:] Bremswiderstand IP54

Series T300 | GWAD-GYAD

Wirewound flat resistor with protection rating IP54 or IP67, housed in an anodized aluminum enclosure.

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Mobile resistors for discharging capacitors

During maintenance work on wind turbines, DC link capacitors must be discharged in a safe and controlled way – especially at voltages up to 1000 V, where protecting personnel and equipment is of utmost importance.

With its compact discharge resistor designed for mobile use, FRIZLEN offers a practical solution tailored specifically to the needs of service operations.

The mobile discharge resistor is based on robust, encapsulated flat resistors and housed in a durable enclosure with an IP54 protection rating. An attached switch box with a safety switch ensures safe operation by service personnel – even under demanding environmental conditions. Thanks to its well-thought-out design, the unit is easy to transport and can be used flexibly in the field.

Series T400 | FDLZ

Portable discharge resistor with integrated safety switch.

Power resistors for PV inverters

Solar energy is gaining increasing importance in the overall energy mix – and even more so in everyday perception. In addition to small rooftop systems, large-scale installations in open fields are increasingly shaping the landscape.

PV system operators face high demands from grid operators to ensure high grid quality. FRIZLEN resistors play a crucial role in meeting these requirements.

Damping resistors for grid filters in PV systems

Photovoltaic systems feed electrical energy into the grid through inverters. The switching frequency of power electronics often generates unwanted harmonics and high-frequency disturbances, which can lead to grid interference. Three-phase damping resistors – also known as filter resistors – are a key component of passive LCL or RLC grid filters, providing effective damping of these disturbances.

FRIZLEN provides customized filter resistors for PV applications with the highest requirements for operational safety, temperature resistance, and long-term stability. Our solutions are specifically designed for integration into grid-side filters, enabling targeted damping of resonance frequencies in conjunction with inductances and capacitances.

[Translate to English:] Filterwiderstand IP00

Series T600 | FKEY 31

Steel grid resistor with IP00 protection rating, designed for high continuous currents

Resistors in distribution networks

The distribution of electricity from the generator to the consumer plays a crucial role in today's energy mix. The increasingly decentralized generation of electricity necessitates the extensive expansion of networks.

Grid operators face enormous technical challenges in maintaining network stability and balancing power supply and demand.

Damping resistors in switch plants

Damping resistors are used in oscillation suppression circuits to reduce transient oscillations at voltage transformers in medium-voltage networks.

Such oscillations in resonant circuits composed of inductive and capacitive elements can be triggered by switching operations or lightning strikes. In unfavorable cases, they may cause severe damage to valuable switch plants, which is why they must be minimized.

FRIZLEN damping resistors, connected to the e-n auxiliary winding of voltage transformers, extract active power from the resonant circuit, thereby effectively reducing transient oscillations.

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Load resistors for negative balancing power

In modern energy supply systems – especially with the increasing share of renewable energy – maintaining grid stability is becoming ever more challenging. One possible component for ensuring frequency stability is the targeted use of load resistors to absorb negative balancing power. A load resistor for negative balancing power is used when surplus electrical energy in the grid must be absorbed momentarily – for example, during sudden oversupply or in response to grid faults requiring regulation.

FRIZLEN offers load resistors specifically designed to meet individual customer requirements for this purpose.