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Series Resonance Test Device

LHV-135kVA/108kV Resonant Test System for High Voltage Cable & Transformer Testing

Professional 135kVA/108kV resonant test system for large capacity HV cable (up to 3km) and transformer testing. Features DSP technology, multi-protection functions, and lightweight field operation.


  • US$1.00; Negotiated Price
  • Lead time: 90days

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Product Details

Product Tags

LHV-135kVA/108kV Resonant Test System for High Voltage Applications

Product Introduction

The LHV-135kVA/108kV Resonant Test System represents the cutting-edge solution for high-voltage cable and transformer testing, combining advanced DSP technology with series resonance principles to deliver unmatched testing efficiency. Compliant with GB 50150-2016, DL/T 849.6-2016, and DL/T 474.4-2018 standards, this system is engineered for demanding field applications.

Main components of the device

Serial numberDevice nameSpecification and modelUnitQuantity
1Variable frequency power supplyLHV-7.5kWTower1
2Excitation transformerLHV-7.5kVA/1.5/3/6kV/0.4kVTower1
3High voltage reactorLHV-33.75kVA/27kVSection4
4Capacitive voltage dividerLHV-1000pF/110kVSet1

Main Functions and Features

The UHV-135kVA/108kV series resonance scheme adopts the method of adjusting the power supply frequency to achieve resonance between the reactor and the test capacitor, thereby obtaining high voltage and large current on the test object. Due to its small required power supply, light weight, and compact size, it has received widespread acclaim and application both domestically and internationally. It represents a new method and trend in high-voltage testing.

The main functions and technical features of our company's frequency conversion resonance device are as follows:

1, Protection Functions: The device is equipped with protection functions such as overvoltage, overcurrent, zero-start, and system detuning (flashover). The overvoltage and overcurrent protection values can be set according to user needs. In case of test object flashover, the flashover protection will activate and record the flashover voltage value for test analysis.

2, Lightweight Design: The entire device is lightweight, making it easy to use on-site.

3, Multiple Operation Modes: The device offers three working modes: fully automatic mode, manual mode, and automatic tuning with manual voltage boosting mode. This allows users to flexibly choose based on on-site conditions, improving test efficiency.

4, Data Storage and Printing: The device can store and remotely print data. The stored data is numbered digitally, making it easy for users to identify and retrieve.

5, Automatic Frequency Sweeping: During automatic frequency sweeping, the starting frequency can be set arbitrarily within a specified range, and the sweeping direction can be chosen as upward or downward. A large LCD screen displays the scanning curve, allowing users to intuitively understand whether the resonance point has been found.

6, DSP Platform Technology: The device uses DSP platform technology, allowing for the addition or reduction of functions and upgrades based on user needs. The human-machine interface is more user-friendly.

7, Reduced Power Supply Capacity: The series resonance power supply generates high voltage and large current through resonance between the reactor and the test object's capacitance. In the entire system, the power supply only needs to provide the active power consumption, so the required power supply capacity is only 1/Q of the test capacity.

8, Reduced Weight and Volume: The series resonance device eliminates the need for bulky high-power voltage regulators and conventional high-power frequency test transformers. Moreover, the resonant excitation power supply only requires 1/Q of the test capacity, significantly reducing the system's weight and volume, typically to 1/10-1/30 of conventional test devices.

9, Improved Output Voltage Waveform: The resonance power supply uses a resonant filter circuit, which improves the waveform distortion of the output voltage, providing a high-quality sinusoidal waveform and effectively preventing harmonic peaks from causing false breakdowns in the test object.

10, Prevention of Large Short-Circuit Currents: In a series resonance state, when the insulation weak point of the test object breaks down, the circuit immediately detunes, and the current rapidly drops to 1/Q of the normal test current. In contrast, when using parallel resonance or a test transformer for withstand voltage testing, the breakdown current immediately increases by tens of times. Compared to this, the short-circuit current and breakdown current differ by hundreds of times. Series resonance effectively identifies insulation weak points without the risk of large short-circuit currents damaging the fault point.

11, No Recovery Overvoltage: When the test object breaks down, the high voltage immediately disappears due to the loss of resonance conditions, and the arc extinguishes instantly. The process of re-establishing the recovery voltage is long, making it easy to disconnect the power supply before reaching the flashover voltage again. This voltage recovery process is an intermittent oscillation of energy accumulation, which is prolonged and does not result in any recovery overvoltage.

Main technical parameters and functions

Rated capacity135kVA
Rated voltage27kV;54kV;108kV
Rated current5A;2.5A;1.25A
Measurement accuracySystem RMS level 1.5
Operating frequency30-300Hz
Device output waveformSinusoidal wave
Quality factorDevice Q≥30(f=45Hz)
Waveform distortion rateOutput voltage waveform distortion ≤1%
Input power supplySingle-phase 220 or three-phase 380V voltage, frequency 50Hz
Working hoursAllow continuous 60min under rated load; Overpressure 1.1 times 1 minute
Temperature riseTemperature rise ≤65K after continuous operation under rated load for 60 minutes
Protection functionOvervoltage, overcurrent, zero start, system mismatch (flashover) and other protection functions
Ambient temperature-20℃-55℃
Relative humidity≤90%RH
Altitude≤3000m

Device capacity verification (device capacity is 135kVA, divided into three reactors, reactor single section is 33.75kVA/27kV/1.25A/100H)

Serial numberTestTest FrequencyTest Current
110kV/300mm2 cable 3km AC voltage withstand test, capacitance ≤1.1265μF, test frequency 30-300Hz, test voltage 22kV, test time 5min. Use four reactors in parallel, L=100/4=25Hf=1/2π√LC=1/(2×3.14×√25×1.1265×10-6)=30HzI=2πfCU =2π×30×1.1265×10-6×22×103=4.67A
2A35kV/300mm2 cable 1km AC voltage withstand test, capacitance ≤0.1945μF, test frequency 30-300Hz, test voltage 52kV, test time 60min. Use two reactors in series (mutual inductance coefficient 1.15) two groups in parallel, L=100×2×1.15/2=115Hf=1/2π√LC=1/(2×3.14×√115×0.1945×106)=33.65HzI=2πfCU =2π×33.65×0.1945×10-6×52×103=2.14A
3Ac voltage withstand test of 35kV/31500kVA main transformer, capacitance ≤0.02μF, test frequency 45-65Hz, test voltage 68kV, test time 1min. Use four reactors in series (mutual inductance coefficient 1.25), L=100×4×1.25=500Hf=1/2π√LC=1/(2×3.14×√500×0.02×10-6)=50.33HzI=2πfCU =2π×50.33×0.02×10-6×68×103=0.43A

Equipment combination method during testing

Test Object
Combination Method

Reactor Selection
(33.75kVA/27kV four sections)
Excitation Transformer
Output Selection
Test Voltage
(kV)
10kV/300mm2
Cable 3km
Using four reactors in parallel1.5kV≤22kV
10kV switch and other substation equipmentUsing three reactors in series3kV≤42kV
35kV/300mm2
Cable 1km
Using two reactors in series and two groups in parallel3kV≤52kV
35kV/31500kVA main transformerUsing four reactors in series6kV≤68kV
35kV switch and other electrical equipmentUsing four reactors in series6kV≤95kV

System Configuration Parameters

(一) Variable Frequency Power Supply UHV-7.5kW (1 unit)

Rated Output Capacity7.5kW
Operating Power Supply220/380±10%V(single/three-phase), industrial frequency
Output Voltage0-400V
Rated Input Current18.75A
Rated Output Current18.75A
Voltage Resolution0.01kV
Voltage Measurement Accuracy1.5%
Frequency Adjustment Range30-300Hz
Frequency Adjustment Resolution≤0.1Hz
Frequency Stability0.1%
Operating TimeContinuous 60min at Rated Capacity
Maximum Component Temperature at Continuous 60min Operation at Rated Capacity≤65K
Noise Level≤50dB
Dimensions (L×W×H mm)400×280×400
WeightApproximately 10kg

(二) Excitation Transformer UHV-7.5kVA/1.5/3/6kV/0.4kV (1 unit)

Rated Capacity7.5kVA
Input Voltage0-400V
Output Voltage1.5/3/6kV
StructureDry Type
Dimensions (L×W×H mm)450×330×430
WeightApproximately 50kg

(三) High Voltage Reactor UHV-33.75kVA/27kV (4 knots)

Rated Capacity33.75kVA
Rated Voltage27kV
Rated Current1.25A
Inductance100H/unit
Quality FactorQ≥30(f=45Hz)
StructureDry Type
Dimensions (Inner Diameter×Height mm)302×435
WeightApproximately 55kg

(四) Capacitive Voltage Divider UHV-1000pF/110kV (1 set)

Rated Voltage110kV
High Voltage Capacitance1000pF
Dielectric Losstgσ≤0.5%
Voltage Division Ratio1500:1
Measurement AccuracyEffective Value 1.5 Grade
Dimensions (Inner Diameter×Height mm)140×1000
WeightApproximately 8kg

Delivery List

No.Equipment NameModel and SpecificationsUnitQuantity
1Variable Frequency Power SupplyLHV-7.5kWUnit1
2Excitation TransformerLHV-7.5kVA/1.5/3/6kV/0.4kVUnit1
3High Voltage ReactorLHV-33.75kVA/27kVSection4
4Capacitive Voltage DividerLHV-1000pF/110kVSet1
5Internal Connection Cables
Set1
6Factory Inspection Report
Copy1
7User Manual
Copy1
8Product Certificate
Copy1
9Packing List
Copy1

Reference Test Standards

DL/T 596-1996"Preventive Test Code for Electric Power Equipment"
GB50150-2016"Standard for Handover Testing of Electrical Equipment in Electrical Installation Engineering"
GB10229-88"Reactors"
GB1094"Power Transformers"
GB1094.1-GB1094.6-96"Degrees of Protection Provided by Enclosures"
GB2900"Electrotechnical Terminology"
GB/T16927.1~2-1997"High Voltage Test Techniques"
DL/T474.4-2006"Guide for Insulation Test Implementation on Site - AC Withstand Voltage Test"
DL/T1015"Guide for the Use of Voltage Measurement Systems for On-site DC and AC Withstand Voltage Tests"
GB/T311.1-1997"Insulation Coordination and Insulation of High Voltage Power Transmission and Transformation Equipment"
GB191-2000"Pictorial Markings for Packaging and Storage"
JB/T9641-1999"Test Transformers"
IEC358(1990)"Coupling Capacitors and Capacitor Dividers"
GB4793-1984"Safety Requirements for Electronic Measuring Instruments"
GB/T3859.2-1993"Application Guide for Semiconductor Converters"
GB/T2423.8-1995"Basic Environmental Testing Procedures for Electrical and Electronic Products"
DL/T849.6-2004"General Technical Specifications for Special Test Instruments for Power Equipment Part 6: High Voltage Frequency Tuning Test Devices"

Key Specifications:

  • 135kVA/108kV testing capacity

  • 3km cable testing capability (10kV/300mm²)

  • DSP-controlled precision measurement platform

  • 30-300Hz adjustable test frequency range

  • 1/Q power efficiency (up to 90% energy saving)

Standard Test Capabilities

Test ObjectParametersTest VoltageDuration
10kV/300mm² Cable (3km)≤1.1265μF22kV5min
35kV/300mm² Cable (1km)≤0.1945μF52kV60min
35kV/31500kVA Transformer≤0.02μF68kV1min
35kV Switchgear-≤95kV1min

Core Technologies

Series Resonance Principle

The system utilizes LC resonance between the reactor and test object's capacitance to:

  • Generate high voltage with minimal input power (1/Q of test capacity)

  • Produce pure sinusoidal waveforms (THD <3%)

  • Automatically limit fault currents to 1/Q values during breakdown

DSP Control Platform

  • Real-time frequency sweep (30-300Hz range)

  • Automatic resonance point detection

  • Digital protection algorithms

  • Upgradable firmware architecture

Safety Protection System

Overvoltage Protection

110% rated voltage cutoff with 1ms response

Overcurrent Protection

120% current threshold with adjustable settings

Flashover Protection

Automatic arc extinguishing and voltage collapse

Zero-start Interlock

Prevents improper energization sequences

Field Operation Advantages

FeatureLHV-135 SystemConventional Test Sets
Power Requirement10-30kW100-150kW
Total Weight≈800kg≈3000kg
Setup Time<30 minutes2-3 hours
Waveform QualityTHD <3%THD 5-8%

Unique Technical Features

1. Intelligent Frequency Sweep

  • Bidirectional scanning (up/down frequency)

  • Customizable start frequency

  • Visual resonance curve display

2. Flexible Operation Modes

  1. Fully Automatic: One-touch test completion

  2. Semi-Automatic: Manual voltage ramp after auto-tuning

  3. Manual: Expert control mode

3. Data Management

  • 1000+ test records storage

  • Digital timestamp indexing

  • Remote printing capability

Safety Benefits

Fault Current Limitation

Breakdown currents limited to <10% of test current

No Voltage Overshoot

Gradual resonance re-establishment prevents transients

Instant Arc Quenching

Automatic de-energization within 1ms of flashover

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