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GRIDTUNE
Detuned Reactors

Antiresonance harmonic filter reactors for capacitor banks. Three detuning factors — p=7%, p=5.67% and p=14% — covering all standard THDV pollution levels. 2.5 to 100 kvar, 400–690V, aluminium winding. Designed, manufactured and tested to EN 61558-2-20.

400 – 690 V 2.5 – 100 kvar p=7% / 5.67% / 14% Aluminium Winding EN 61558-1 & -2-20
Antiresonance protection
3 detuning options
2.5 – 100 kvar range
Natural cooling (AN)
Thermal protection (NC)
Division 01 — Passive Power Quality

Harmonic protection
for capacitor banks

In power factor correction systems, capacitor banks are vulnerable to harmonic resonance — a condition where the natural frequency of the capacitor-reactor circuit coincides with a harmonic present in the network. This amplifies harmonic currents and can cause capacitor failure, overheating and nuisance tripping.

Detuned reactors solve this by shifting the resonant frequency below the lowest significant harmonic. Connected in series with each capacitor step, the reactor "detunes" the circuit so it cannot amplify harmonics. The detuning factor (p) determines the tuning frequency: p=7% tunes to 189 Hz, p=5.67% to 210 Hz, and p=14% to 134 Hz.

The Forte GRIDTUNE series offers three detuning factors to match every network pollution level — from light harmonic environments to heavily distorted industrial grids with VFDs, arc furnaces and rectifier loads. Available with aluminium winding, 2.5 to 100 kvar, with built-in bimetal thermal protection as standard.

p=7% p=5.67% p=14% Aluminium Winding EN 61558-1 & -2-20
Technical BrochureEN
Forte GRIDTUNE Detuned Reactor
3
Detuning
options
100 kvar
Maximum
power
690 V
Maximum
voltage
EN 61558
International
standard

Warning — hot surface

The reactor runs hot (thermostat opens at 132 °C, thermal class F (155 °C)) and is open-frame — IP00, mounted inside the panel. Isolate the capacitor step and let the reactor cool before handling it.

Technical Specifications

GRIDTUNE — Full Specification

All parameters for Forte GRIDTUNE detuned reactors. Standard range covers 2.5 to 100 kvar at 400–690V.

ParameterSpecification
ProductForte GRIDTUNE Series — Detuned Filter Reactor
TypeThree-phase antiresonance filter reactor
FunctionResonance suppression for capacitor-based PFC systems
Voltage range400V / 440V / 480V / 600V / 660V / 690V
Power range2.5 – 100 kvar
Frequency50 Hz
Detuning factor p=5.67%Resonant freq. 210 Hz — For high 5th harmonic content filtering; high harmonic filter current near resonance
Detuning factor p=7%Resonant freq. 189 Hz — Standard industrial applications with balanced load
Detuning factor p=14%Resonant freq. 134 Hz — Unbalanced loads, with 3rd harmonic present
Winding materialAluminium
Thermal protectionBimetal microswitch (NC contact)
CoolingNatural convection (AN)
Ambient temperature–10 °C to +45 °C (derate above 40 °C)
EnclosureIP00 (open frame — panel mounted)
StandardEN 61558-1 & EN 61558-2-20
Thermostat opening132 °C
Thermal classF (155 °C)
Duty100 %
Lowest unit losses42 W (smallest unit, 2.5 kvar)
Warranty12 months (subject to warranty conditions)
Linearity (p=7%)L ≥ 0.95 × LR for current up to 1.73 × IRMS
Linearity (p=5.67%)L ≥ 0.95 × LR for current up to 1.73 × IRMS
Linearity (p=14%)L ≥ 0.95 × LR for current up to 1.37 × IRMS
Selection Guide

THDV-Based Detuning Factor Selection

Choose the correct detuning factor based on the total harmonic voltage distortion (THDV) of your network.

Type CodeTHDV RangeTypical Environment
T07THDV ≤ 5%Light pollution — offices, commercial buildings, light industry
T08THDV 3–8%Standard — majority of industrial & commercial installations (default choice)
T14THDV > 8%Heavy pollution — VFDs, rectifiers, welding, arc furnaces
Note: If on-site THDV measurement is not available, T08 is the recommended default for standard industrial environments.
Key Features

What Makes GRIDTUNE the Right Choice

Engineered for reliability, efficiency and easy integration into any power factor correction panel.

Antiresonance Protection

Prevents harmful resonance between capacitor banks and network inductance. Protects capacitors, fuses and switchgear from harmonic overcurrents.

3 Detuning Options

p=5.67% (210 Hz) for high 5th harmonic content filtering, p=7% (189 Hz) for standard industrial applications with balanced load, p=14% (134 Hz) for unbalanced loads with 3rd harmonic present.

Low Losses

Optimized core design and high-grade electrical steel minimize heat generation and energy waste. Losses as low as 42 W for the smallest units.

Built-in Thermal Protection

Bimetal microswitch with NC (normally closed) contact embedded in the winding. Disconnects the reactor on overtemperature — no external relay needed.

Wide Voltage Range

Standard models for 400V, 440V, 525V and 690V systems. Covers low-voltage industrial and commercial installations worldwide.

Compact & Panel Ready

IP00 open-frame design mounts directly inside PFC panels. Compact footprint from 2.4 kg (2.5 kvar) to 67.9 kg (100 kvar).

Characteristics — p=7%

Detuned Reactor Data — p=7% · 189 Hz

Standard industrial applications with balanced load. 400 V range.

QC (kvar)VoltageL (mH)In (A)Ieff (A)Losses (W)Weight (kg)Order Code
2.5400V15.33.63.842.862.41DR07-T08400-C03S01
6.25400V6.1399.5170.124.71DR07-T08400-C06S01
10400V3.8414.415.2156.0281DR07-T08400-C10S01
12.5400V3.0718.119.1180.029.31DR07-T08400-C13S01
20400V1.922930.63101.9512.81DR07-T08400-C20S01
25400V1.5336.138.12125.2113.41DR07-T08400-C25S01
40400V0.9557.760.94172.718.11DR07-T08400-C40S01
50400V0.7672.276.26221.8211DR07-T08400-C50S01
75400V0.51108114.1289.227.61DR07-T08400-C75S01
100400V0.38145153353.842.41DR07-T08400-C100S01
Characteristics — p=5.67%

Detuned Reactor Data — p=5.67% · 210 Hz

High 5th harmonic content — high filter current near resonance. 400 V range.

QC (kvar)VoltageL (mH)In (A)Ieff (A)Losses (W)Weight (kg)Order Code
2.5400V12.253.64.17961.372.71DR56-T08400-C03S01
6.25400V4.9910.4888.247.21DR56-T08400-C06S01
10400V3.0616.7916.7995.057.41DR56-T08400-C10S01
12.5400V2.331922.09114.188.11DR56-T08400-C13S01
20400V1.5328.933.62119.913.71DR56-T08400-C20S01
25400V1.2236.142.01146.515.61DR56-T08400-C25S01
40400V0.7657.767.15213.119.91DR56-T08400-C40S01
50400V0.5875.988.34238.231.51DR56-T08400-C50S01
75400V0.41108125.7320.651.21DR56-T08400-C75S01
100400V0.31144167.643152.21DR56-T08400-C100S01
Characteristics — p=14%

Detuned Reactor Data — p=14% · 134 Hz

Unbalanced loads with 3rd harmonic present. 400 V range.

QC (kvar)VoltageL (mH)In (A)Ieff (A)Losses (W)Weight (kg)Order Code
2.5400V33.23.63.6355.963.91DR14-T08400-C03S01
6.25400V13.399.0670.568.91DR14-T08400-C06S01
10400V8.314.414.4994.7510.21DR14-T08400-C10S01
12.5400V6.631818.11118.212.61DR14-T08400-C13S01
20400V4.1528.929.08168.7416.11DR14-T08400-C20S01
25400V3.3236.136.32144.519.21DR14-T08400-C25S01
40400V2.0757.758.06192.133.81DR14-T08400-C40S01
50400V1.6672.272.6528342.51DR14-T08400-C50S01
75400V1.11109109.633455.51DR14-T08400-C75S01
100400V0.83144144.9425.367.91DR14-T08400-C100S01
Applications

Where GRIDTUNE Detuned Reactors Are Used

Detuned reactors are specified wherever capacitor banks operate in networks with harmonic pollution.

⚡

PFC Panels

Standard power factor correction panels with switched capacitor steps. The primary application for detuned reactors.

🏭

VFD-Heavy Plants

Facilities with variable frequency drives generating 5th and 7th harmonics that threaten capacitor banks.

⛏

Steel & Metals

Arc furnaces, induction furnaces and rolling mills with high harmonic distortion and reactive power demand.

🏯

Cement & Mining

Large motor loads with significant harmonic content. Ball mills, crushers and conveyor drives.

🏪

Commercial Buildings

Shopping malls, hospitals and data centres with UPS systems, LED lighting and IT loads generating harmonics.

☀

Renewables

Solar inverter and wind turbine installations where harmonic filters protect grid-side capacitor banks.

Selection Guide

Which detuning factor

On a detuned reactor the real decision is the detuning factor — it sets the resonant frequency, and with it which harmonic you are protected against. You choose it from the character of your load.

p = 5.67 %
Resonance 210 Hz

High 5th harmonic content. High filter current near resonance.

Code 56
p = 7 %DEFAULT
Resonance 189 Hz

Standard industrial applications with balanced load.

Code 07 Capacitor 525 V
p = 14 %
Resonance 134 Hz

Unbalanced loads with 3rd harmonic present.

Code 14 Capacitor 800 V

The reactor and the capacitor are selected together

On a 400V network a p = 7 % step uses a 525V capacitor and a p = 14 % step uses an 800V capacitor. The reactor raises the voltage across the capacitor; the wrong pairing runs the capacitor over-voltage.

THDV Type Code

How polluted your network is

The type code follows the measured voltage distortion.

Type codeTHDV rangeTypical environment
T07THDV ≤ 5 %Light pollution — offices, commercial buildings, light industry
T08THDV 3 – 8 %Standard — majority of industrial & commercial installations
T14THDV > 8 %Heavy pollution — VFDs, rectifiers, welding, arc furnaces

If an on-site THDV measurement is not available, T08 is the recommended value for a standard industrial environment.

Ordering Code

How the code is built

A GRIDTUNE code has five fields. Example: p = 7 %, T08, 400V, 100 kvar.

1DR
07
–
T08
400
–
C100
S01

Colours match each code field to its row below · 1DR is the fixed prefix · 1DR07-T08400-C100S01

Detuning factorfield 2
56 p = 5.67 % · 210 Hz07 p = 7 % · 189 Hz14 p = 14 % · 134 Hz
THDV type codefield 3
T07 THDV ≤ 5 %T08 THDV 3 – 8 %T14 THDV > 8 %
System voltagefield 4
400 V

The catalogue is built around 400V. Other system voltages on request.

Capacitor outputfield 5
C03 2.5 kvarC06 6.25 kvarC10 10 kvarC13 12.5 kvarC20 20 kvarC25 25 kvarC40 40 kvarC50 50 kvarC75 75 kvarC100 100 kvar

The code carries the rounded kvar value — 2.5 → C03 · 6.25 → C06 · 12.5 → C13.

Seriesfield 6
S01

Production / supply generation.

Need help selecting the right detuned reactor?

Our engineering team will recommend the optimal detuning factor and power rating based on your network analysis, capacitor bank configuration and harmonic profile.

Documents

Technical documents for this product. Ask for a document still in preparation and we will send it as soon as it is ready.

Technical BrochureEN Download PDF Technical BrochureTR Download PDF

Request a Quote — GRIDTUNE Detuned Reactors

Our engineering team will contact you within 1 business day. Urgent: +90 850 840 64 24

Order code 1DR__-______-C__S01 Pick a detuning factor, a type code and an output — the code builds itself.

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