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

Send email to us

>>>WhatsApp Communication<<<

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 number	Device name	Specification and model	Unit	Quantity
1	Variable frequency power supply	LHV-7.5kW	Tower	1
2	Excitation transformer	LHV-7.5kVA/1.5/3/6kV/0.4kV	Tower	1
3	High voltage reactor	LHV-33.75kVA/27kV	Section	4
4	Capacitive voltage divider	LHV-1000pF/110kV	Set	1

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 capacity	135kVA
Rated voltage	27kV；54kV；108kV
Rated current	5A；2.5A；1.25A
Measurement accuracy	System RMS level 1.5
Operating frequency	30-300Hz
Device output waveform	Sinusoidal wave
Quality factor	Device Q≥30(f=45Hz)
Waveform distortion rate	Output voltage waveform distortion ≤1%
Input power supply	Single-phase 220 or three-phase 380V voltage, frequency 50Hz
Working hours	Allow continuous 60min under rated load; Overpressure 1.1 times 1 minute
Temperature rise	Temperature rise ≤65K after continuous operation under rated load for 60 minutes
Protection function	Overvoltage, 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 number	Test	Test Frequency	Test Current
1	10kV/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=25H	f=1/2π√LC=1/(2×3.14×√25×1.1265×10^-6)=30Hz	I=2πfCU =2π×30×1.1265×10^-6×22×10³=4.67A
2	A35kV/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=115H	f=1/2π√LC=1/(2×3.14×√115×0.1945×10⁶)=33.65Hz	I=2πfCU =2π×33.65×0.1945×10^-6×52×10³=2.14A
3	Ac 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=500H	f=1/2π√LC=1/(2×3.14×√500×0.02×10^-6)=50.33Hz	I=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 parallel	1.5kV	≤22kV
10kV switch and other substation equipment	Using three reactors in series	3kV	≤42kV
35kV/300mm² Cable 1km	Using two reactors in series and two groups in parallel	3kV	≤52kV
35kV/31500kVA main transformer	Using four reactors in series	6kV	≤68kV
35kV switch and other electrical equipment	Using four reactors in series	6kV	≤95kV

System Configuration Parameters

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

Rated Output Capacity	7.5kW
Operating Power Supply	220/380±10%V(single/three-phase), industrial frequency
Output Voltage	0-400V
Rated Input Current	18.75A
Rated Output Current	18.75A
Voltage Resolution	0.01kV
Voltage Measurement Accuracy	1.5%
Frequency Adjustment Range	30-300Hz
Frequency Adjustment Resolution	≤0.1Hz
Frequency Stability	0.1%
Operating Time	Continuous 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
Weight	Approximately 10kg

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

Rated Capacity	7.5kVA
Input Voltage	0-400V
Output Voltage	1.5/3/6kV
Structure	Dry Type
Dimensions (L×W×H mm)	450×330×430
Weight	Approximately 50kg

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

Rated Capacity	33.75kVA
Rated Voltage	27kV
Rated Current	1.25A
Inductance	100H/unit
Quality Factor	Q≥30(f=45Hz)
Structure	Dry Type
Dimensions (Inner Diameter×Height mm)	302×435
Weight	Approximately 55kg

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

Rated Voltage	110kV
High Voltage Capacitance	1000pF
Dielectric Loss	tgσ≤0.5%
Voltage Division Ratio	1500:1
Measurement Accuracy	Effective Value 1.5 Grade
Dimensions (Inner Diameter×Height mm)	140×1000
Weight	Approximately 8kg

Delivery List

No.	Equipment Name	Model and Specifications	Unit	Quantity
1	Variable Frequency Power Supply	LHV-7.5kW	Unit	1
2	Excitation Transformer	LHV-7.5kVA/1.5/3/6kV/0.4kV	Unit	1
3	High Voltage Reactor	LHV-33.75kVA/27kV	Section	4
4	Capacitive Voltage Divider	LHV-1000pF/110kV	Set	1
5	Internal Connection Cables		Set	1
6	Factory Inspection Report		Copy	1
7	User Manual		Copy	1
8	Product Certificate		Copy	1
9	Packing List		Copy	1

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 Object	Parameters	Test Voltage	Duration
10kV/300mm² Cable (3km)	≤1.1265μF	22kV	5min
35kV/300mm² Cable (1km)	≤0.1945μF	52kV	60min
35kV/31500kVA Transformer	≤0.02μF	68kV	1min
35kV Switchgear	-	≤95kV	1min

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

Feature	LHV-135 System	Conventional Test Sets
Power Requirement	10-30kW	100-150kW
Total Weight	≈800kg	≈3000kg
Setup Time	<30 minutes	2-3 hours
Waveform Quality	THD <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

Fully Automatic: One-touch test completion
Semi-Automatic: Manual voltage ramp after auto-tuning
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