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AC Resonant Test System

AC Resonant Test Systems: Variable Frequency & Variable Inductance Sets (44 kVA to 540 kVA)

Shanghai DEMIKS Electric Power Technology Co., LTD (DEMIKS) engineers and supplies high-voltage AC resonant test systems from the Lingang Special Area of the China (Shanghai) Pilot Free Trade Zone. Our DBP-DL series spans 44 kVA / 44 kV to 540 kVA / 270 kV for complete mobile systems, with modular cylinder reactors reaching 400 kV per unit and 1,600 kV in four-unit cascades. Every variable frequency AC resonant test system is built for efficient high-voltage testing of electrical equipment, verifying insulation reliability across power cables, gas-insulated switchgear (GIS), power transformers, and rotating generators.

  • Dual Resonant Architectures:

    01

    Choose 20–300 Hz variable frequency series resonant test sets or 50 Hz / 60 Hz variable inductance resonant test systems.

  • Verified Low Partial Discharge:

    02

    Background partial discharge is held to ≤5 pC for PD-free cable test configurations and <10 pC for dry-type cylinder reactors.

  • High Quality Factor & Sine Wave Purity:

    03

    Reactor quality factor Q ≥ 30 at 45 Hz reduces required input power supply capacity, while output waveform distortion stays ≤1% with RMS Class 1.5 measurement accuracy.

  • Fast Engineering Turnaround:

    04

    Quotes are returned within 24 hours on business days, reviewed by an engineer, with 15–30 working days standard lead time and a 1 set minimum order quantity.

Request a 24-Hour Engineered Configuration & Quote DEMIKS DBP-DL Series • Shanghai Lingang FTZ
DBP-DL // HV-AC
DEMIKS DBP-DL variable-frequency series resonant test set
DEMIKS DBP-DL variable-frequency series resonant test set configured with dry epoxy-cast reactors, excitation transformer, capacitive divider, and optical-fiber isolated control unit.

44–540 kVA

SPEC 01

7 standard DBP-DL complete systems (44 kV to 270 kV output; 400 kV, 1,600 kV modular cylinder cascades)

20–300 Hz

SPEC 02

Variable frequency sweep with 0.1 Hz frequency resolution, plus 50 Hz / 60 Hz variable inductance sets

≤5 pC / <10 pC

SPEC 03

Background partial discharge noise floor for PD-free cable systems and epoxy cylinder reactors

Q ≥ 30 (f=45 Hz)

SPEC 04

High reactor quality factor lowers input power supply demand to active circuit losses

≤65 K (60 Min)

SPEC 05

Continuous 60-minute full-load factory heat-run limit plus 1.1x overvoltage withstand for 1–3 minutes

15–30 Working Days

SPEC 06

Standard manufacturing lead time, 1 set MOQ, T/T & L/C payment, and 24 hours engineer quote response

DEMIKS DBP-DL Series US Patent US4338561A Architecture

Complete System Model Matrix (44 kVA to 540 kVA) and Sub-Component Specifications

Selecting a high voltage resonant test system requires matching both rated output voltage and capacitive charging current to the test object. A test system may have sufficient voltage capability for target kilovolts yet fail on a multi-kilometer power cable if its reactor current rating is undersized. Below are all 7 complete DBP-DL variable-frequency series resonant systems and 11 matched sub-components (variable-frequency power sources, excitation transformers, high-voltage reactors, and capacitive dividers) with an interactive model filter.

Series Resonant Tank Topology Click stage to filter sub-components
44–540 kVA Rated Capacity
22–270 kV Output Voltage
20–300 Hz Sweep Range
Q ≥ 30 Quality Factor
Showing 18 / 18

Complete DBP-DL Systems (7 Models)

7 Models Displayed
DBP-DL-44kVA/44kV/22kV AC Resonant Test System
Complete System Model

DBP-DL-44kVA/44kV/22kV

Rated Capacity 44 kVA
Output Voltage Combinations 22 kV (parallel) / 44 kV (series)
Rated Current Stages 2 A / 1 A
Operating Frequency & Quality Factor 20–300 Hz, 0.1 Hz resolution, Q ≥ 30 (f=45 Hz)
Primary Target Test Objects: 6–10 kV XLPE distribution cables, 10 kV switchgear, and dry-type instrument transformers
DBP-DL-108kVA/108kV/27kV AC Resonant Test System
Complete System Model

DBP-DL-108kVA/108kV/27kV

Rated Capacity 108 kVA
Output Voltage Combinations 27 kV / 54 kV / 108 kV (four 27 kV reactors)
Rated Current Stages 4 A / 2 A / 1 A
Operating Frequency & Quality Factor 20–300 Hz, ≤1% waveform distortion, Q ≥ 30
Primary Target Test Objects: 10–35 kV extruded power cables, 35 kV substation buses, and SF6 circuit breakers
DBP-DL-108kVA/108kV/36kV AC Resonant Test System
Complete System Model

DBP-DL-108kVA/108kV/36kV

Rated Capacity 108 kVA
Output Voltage Combinations 36 kV / 72 kV / 108 kV (three 36 kV reactors)
Rated Current Stages 3 A / 1.5 A / 1 A
Operating Frequency & Quality Factor 20–300 Hz, single reactor weight ≤120 kg, Q ≥ 30
Primary Target Test Objects: 35 kV XLPE cables, 35 kV main power transformers, and substation insulators
DBP-DL-216kVA/108kV/27kV AC Resonant Test System
Complete System Model

DBP-DL-216kVA/108kV/27kV

Rated Capacity 216 kVA
Output Voltage Combinations 27 kV / 54 kV / 108 kV (high-current parallel/series)
Rated Current Stages 8 A / 4 A / 2 A
Operating Frequency & Quality Factor 20–300 Hz, RMS Class 1.5 accuracy, Q ≥ 30
Primary Target Test Objects: Long-distance 10–35 kV feeder cables requiring high capacitive charging current
DBP-DL-216kVA/216kV AC Resonant Test System
Complete System Model

DBP-DL-216kVA/216kV

Rated Capacity 216 kVA
Output Voltage Combinations 54 kV / 108 kV / 216 kV
Rated Current Stages 4 A / 2 A / 1 A
Operating Frequency & Quality Factor 20–300 Hz, 60-min rated thermal duty ≤65 K
Primary Target Test Objects: 66–110 kV XLPE cables, 110 kV GIS bays, and substation step-up transformers
DBP-DL-270kVA/270kV/45kV AC Resonant Test System
Complete System Model

DBP-DL-270kVA/270kV/45kV

Rated Capacity 270 kVA
Output Voltage Combinations 45 kV / 90 kV / 135 kV / 270 kV
Rated Current Stages 6 A / 3 A / 2 A / 1 A
Operating Frequency & Quality Factor 20–300 Hz, 220 V / 380 V input supply, Q ≥ 30
Primary Target Test Objects: 110–220 kV substation primary apparatus, GIS switchgear, and medium-length 110 kV cables
DBP-DL-540kVA/270kV/27kV AC Resonant Test System
Complete System Model

DBP-DL-540kVA/270kV/27kV

Rated Capacity 540 kVA
Output Voltage Combinations 45 kV / 90 kV / 135 kV / 270 kV (multi-unit cascade)
Rated Current Stages 12 A / 6 A / 4 A / 2 A
Operating Frequency & Quality Factor 20–300 Hz, ≤1% THD sine wave, Q ≥ 30 (f=45 Hz)
Primary Target Test Objects: 110–220 kV long XLPE underground cables, 220 kV GIS systems, and large power generators

Every DBP-DL resonant test system is assembled from four matched functional sub-systems: a variable-frequency power supply control console, an excitation transformer, dry-type or oil-immersed high-voltage reactors, and a capacitive voltage divider. Below are the 11 verified DEMIKS sub-component models used to configure custom test bays. This series resonant tank architecture follows the foundational variable-frequency tuning principle established in US Patent US4338561A.

Sub-Component Specifications (11 Models)

11 Sub-Components Displayed
DBP-DL-6kVA Variable-Frequency Power Source
Sub-Component Model · Component Type: Variable-Frequency Power Source

DBP-DL-6kVA

Rated Capacity / Ratio 6 kW
Voltage & Current / Inductance / Capacitance Input 220 V / 380 V; Output 0–400 V sine wave
Key Electrical & Mechanical Parameters 30–300 Hz (20–300 Hz sweep), ≤0.1 Hz resolution, 0.1% frequency stability documented in factory reports, 60-min heat rise ≤65 K
DBP-DL-15kVA Variable-Frequency Power Source
Sub-Component Model · Component Type: Variable-Frequency Power Source

DBP-DL-15kVA

Rated Capacity / Ratio 15 kW
Voltage & Current / Inductance / Capacitance Input 220 V / 380 V; Output 0–400 V sine wave
Key Electrical & Mechanical Parameters Embedded touch screen, automatic resonance tracking, over-voltage / over-current / flashover protection
DLB-6kVA Excitation Transformer
Sub-Component Model · Component Type: Excitation Transformer

DLB-6kVA

Rated Capacity / Ratio 6 kVA
Voltage & Current / Inductance / Capacitance HV taps 1.5 kV / 3.0 kV / 6.0 kV
Key Electrical & Mechanical Parameters Dry-type or oil-insulated, background partial discharge <5 pC, isolates LV inverter from HV resonant loop
DLB-15kVA Excitation Transformer
Sub-Component Model · Component Type: Excitation Transformer

DLB-15kVA

Rated Capacity / Ratio 15 kVA
Voltage & Current / Inductance / Capacitance HV taps 2.5 kV / 5.0 kV / 10 kV / 15 kV
Key Electrical & Mechanical Parameters 60-minute continuous full-load temperature rise ≤65 K, Electrostatic inter-winding shield for PD suppression
DDK-22kVA/22kV/100H Dry-Type Resonant Reactor
Sub-Component Model · Component Type: Dry-Type Resonant Reactor

DDK-22kVA/22kV/100H

Rated Capacity / Ratio 22 kVA
Voltage & Current / Inductance / Capacitance 22 kV rated voltage, 1 A current, 100 H inductance
Key Electrical & Mechanical Parameters Cycloaliphatic epoxy resin casting, non-magnetic base, Q ≥ 30 at 45 Hz, single unit weight ≤120 kg
DDK-27kVA/27kV/100H Dry-Type Resonant Reactor
Sub-Component Model · Component Type: Dry-Type Resonant Reactor

DDK-27kVA/27kV/100H

Rated Capacity / Ratio 27 kVA
Voltage & Current / Inductance / Capacitance 27 kV rated voltage, 1 A current, 100 H inductance
Key Electrical & Mechanical Parameters Stackable in series up to 108 kV or parallel up to 4 A; 60-minute continuous load temperature rise ≤65 K
DDK-36kVA/36kV/100H Dry-Type Resonant Reactor
Sub-Component Model · Component Type: Dry-Type Resonant Reactor

DDK-36kVA/36kV/100H

Rated Capacity / Ratio 36 kVA
Voltage & Current / Inductance / Capacitance 36 kV rated voltage, 1 A current, 100 H inductance
Key Electrical & Mechanical Parameters Designed for 35 kV cable and transformer AC withstand testing; background PD <10 pC at rated voltage
DDK-54kVA/27kV/70H Dry-Type Resonant Reactor
Sub-Component Model · Component Type: Dry-Type Resonant Reactor

DDK-54kVA/27kV/70H

Rated Capacity / Ratio 54 kVA
Voltage & Current / Inductance / Capacitance 27 kV rated voltage, 2 A current, 70 H inductance
Key Electrical & Mechanical Parameters High-current module for multi-kilometer XLPE cable commissioning; 1.1x overvoltage withstand for 3 minutes
DFY-60kV/1000pF Capacitive Voltage Divider
Sub-Component Model · Component Type: Capacitive Voltage Divider

DFY-60kV/1000pF

Rated Capacity / Ratio 60 kV RMS
Voltage & Current / Inductance / Capacitance 1,000 pF nominal capacitance
Key Electrical & Mechanical Parameters Functions as both high-voltage divider and resonant compensation / coupling capacitor; dielectric loss <0.05% per the standard
DFY-100kV/500pF Capacitive Voltage Divider
Sub-Component Model · Component Type: Capacitive Voltage Divider

DFY-100kV/500pF

Rated Capacity / Ratio 100 kV RMS
Voltage & Current / Inductance / Capacitance 500 pF nominal capacitance
Key Electrical & Mechanical Parameters System voltage measurement accuracy ≤±1% (Class 1.5 effective system accuracy); coaxial shielded output lead
DFY-110kV/1000pF Capacitive Voltage Divider
Sub-Component Model · Component Type: Capacitive Voltage Divider

DFY-110kV/1000pF

Rated Capacity / Ratio 110 kV RMS
Voltage & Current / Inductance / Capacitance 1,000 pF nominal capacitance
Key Electrical & Mechanical Parameters Cascadeable for 220 kV / 270 kV field AC withstand testing with double-ring corona grading shields

Engineering Boundary: Output Voltage vs. Cable System Voltage Class:

The 7 standard DBP-DL complete models (44 kV to 270 kV maximum output voltage) directly cover field AC withstand testing up to 110 kV rated cable classes (where 2 U₀ equals 128 kV). Commissioning 220 kV cables (2 U₀ = 256 kV with margin) or 500 kV extra-high-voltage cables requires custom multi-unit reactor cascades up to 400 kV per single cylinder reactor or 1,600 kV in a four-unit cascade.

to filter configurations by cable length and voltage class.

Variable Frequency vs. Variable Inductance Architectures and Reactor Construction

Engineers procuring an AC resonant test system must first decide between two tuning principles: variable frequency series resonance (20–300 Hz) and variable inductance series resonance (50 Hz / 60 Hz). The movable air-gap core mechanism used in variable-inductance reactors follows the dual active core design in US Patent US8203412B2. They must also select between modular epoxy-glass cylinder reactors and grounded metal tank reactors based on whether the system operates in a mobile field trailer or a permanent factory test bay.

Variable Frequency vs. Variable Inductance Architectures and Reactor Construction
Engineering Dimension Variable Frequency Series Resonant System (DBP-DL Series) Variable Inductance Resonant Test System (50 Hz / 60 Hz Series)
Resonance Tuning Mechanism Fixed reactor inductance L (combined in series or parallel); variable-frequency converter sweeps 20–300 Hz (0.1 Hz resolution) per US4338561A principle Fixed power frequency (50 Hz / 60 Hz or higher); rare-earth motor adjusts magnetic core air-gap distance to vary inductance L smoothly per US8203412B2
Quality Factor (Q) & Input Power Q ≥ 30 at 45 Hz under rated load; inverter supplies only active circuit losses (S_test / Q) Q ranges from 10 to 100 depending on air-gap position; requires only 1/Q of test reactive power from mains regulator
Partial Discharge & Filter Design Optical-fiber control isolation with ≤1% sine wave distortion; PD ≤5 pC with high-voltage blocking impedance filter Low-voltage power filter plus high-voltage isolation impedance and coupling capacitor; pure 50/60 Hz sine wave ideal for IEC 60270 PD diagnostics
Module Weight & Field Mobility Compact dry-cast or oil cylinder modules (single unit ≤120 kg for sets ≤108 kVA); ideal for substation vans and cable tunnels Heavier motorized core mechanism; preferred for cable factories, type-test halls, and strict 50/60 Hz transformer or generator tests

Modular Cylinder Type Resonant Reactor (Up to 400 kV Single / 1,600 kV Cascade)

DEMIKS modular cylinder reactors use an epoxy-reinforced glass-fiber insulating shell filled with transformer oil and fitted with an internal oil-resistant expansion diaphragm. A single insulating cylinder reactor can be rated up to 400 kV, and four units stacked in series reach 1,600 kV for extra-high-voltage laboratory and field testing. Double-ring corona sharing shields and a non-magnetic steel base allow fast assembly and disassembly for short-duration IEC withstand tests.

Grounded Metal Tank Type Resonant Reactor (Continuous Factory Duty)

For high-capacitance cable factories and continuous routine testing, DEMIKS supplies grounded metal tank reactors that can be placed directly next to laboratory walls or outdoors using a wall bushing. In variable-inductance metal tank designs, the excitation transformer can be built directly inside the grounded steel tank to save floor space. Metal tank reactors support continuous operation, multi-tap windings, and series connection on insulated pedestals.

Partial Discharge Noise Floor (≤5 pC vs. ≤10 pC) and Alternative HV Test Comparison

Data from more than 800 high-voltage XLPE cable circuits commissioned by Tecnalia Electrical Laboratories show that nearly 30% of field failures are caused by issues at joint and termination interfaces. As reported by INMR field diagnostics, nearly 80% of insulation defects in extruded power cables can be detected using partial discharge measurement per IEC 60270. A simple pass/fail test overvoltage hold.

High-Voltage Test Technology Operating Frequency & Waveform Applicable Cable & Equipment Scope Partial Discharge (PD) Compatibility Power Supply & Weight Trade-Off
DEMIKS PD-Free AC Resonant Test System 20–300 Hz (VF) or 50/60 Hz (VI), pure sine wave with ≤1% THD 35 kV to 500 kV XLPE cables (IEC 60840, IEC 62067), GIS (IEC 62271-203), and HV transformers Internal background noise ≤5 pC (PD-free cable sets) or <10 pC (dry cylinder reactors) for synchronous IEC 60270 PD measurement Input power is only 1/30 to 1/50 of reactive kVA; modular units replace single 20-ton transformers
Power Frequency Test Transformer System 50 Hz / 60 Hz mains sine wave 6 kV to 110 kV short factory samples and routine insulator tests Compatible with pulse-current PD detectors (0.1–10,000 pC, sensitivity ≤0.5 pC) in shielded halls Requires 1:1 kVA power supply capacity; bulky oil-immersed tanks are impractical for long field cables
0.1 Hz Very Low Frequency (VLF) Hipot 0.1 Hz sinusoidal or cosine-rectangular wave (VLF test set) 6 kV to 35 kV medium-voltage distribution cables per IEEE 400.2 Supports VLF tan delta and PD location, unlike conventional hipot test equipment Very compact HV testing equipment for MV maintenance, but not accepted as primary HV/EHV test in IEC 62067
Damped AC (DAC) Voltage System 20–500 Hz decaying oscillating wave (damped AC testing via HVDC charge) Field diagnostic screening and PD localization per IEEE 400.4 Effective for PD inception voltage (PDIV) and joint defect localization Low input power, but applies decaying bursts rather than a continuous 60-minute IEC thermal/voltage soak
DC High-Voltage Generator (DC Hipot) Direct current (ripple factor ≤1% to ≤5%) HVDC submarine/land cables and legacy 6–35 kV auxiliary checks Cannot replicate AC capacitive field grading or AC partial discharge phase patterns Lightweight, but prohibited on service-aged AC XLPE cables by IEEE 400.1 due to destructive space-charge accumulation
Partial Discharge Noise Floor (≤5 pC vs. ≤10 pC) and Alternative HV Test Comparison

Technical Boundary: Equipment Noise Floor vs. On-Site IEC 60270 PD Loop:

DEMIKS's specified partial discharge ratings (≤5 pC for PD-free cable test configurations and <10 pC for dry-type cylinder reactors) define the internal background noise floor of the high-voltage power source, excitation transformer (<5 pC), and reactor assembly. Achieving ≤5–10 pC diagnostic sensitivity in an unshielded outdoor substation requires a complete IEC 60270 measurement circuit with high-voltage blocking impedance filters, star single-point grounding, corona-shielded high-voltage tubes, and ultrasonic or high-frequency current transformer (HFCT) sensors. Inductive-capacitive resonant filtering of supply harmonics is detailed in US Patent US4338561A.