Qumtrix · VLF-TD Tan-Delta Test System

VLF-TD Series
Integrated VLF Withstand & Tan-Delta Test System

VLF-TD 34 kV & 45 kV integrated VLF withstand and tan-delta test system for XLPE / PE / paper-insulated medium-voltage cables. 0.1 Hz sine plus DC and trapezoidal square-wave output, automated three-tier (0.5 Uⁱ / 1.0 Uⁱ / 1.5 Uⁱ) tan-delta cycle, sheath testing to 10 kV with fault pinpointing. Designed to CENELEC HD 620/621 S1 and aligned with GB/T 26852 / GB/T 26860-2011.

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Product Overview

Integrated VLF withstand and tan-delta diagnostic system for medium-voltage cables, from on-site commissioning to predictive maintenance.

0.1 Hz – 0.05 Hz sine, DC and trapezoidal output · three-tier tan-delta cycle · sheath testing to 10 kV.

VLF tan-delta connection diagram
Connection

Dual Test-Connection Configurations

Two wiring setups to suit varying field test requirements

Test Connection Setup 1

Main‑Cable Withstand & Tan‑Delta Test

Standard VLF withstand & tan‑delta connection for medium‑voltage cable commissioning and routine diagnostic testing.

Test Connection Setup 2

Outer‑Sheath DC Test & Fault Pinpointing

Dedicated DC wiring for outer‑sheath integrity verification and sheath‑fault pinpointing.

Capabilities

Built for Cable Diagnostics in the Field

Six capabilities purpose-built for medium-voltage cable commissioning, after-lay testing and predictive maintenance in the field.

VLF Output
0.1 Hz Pure Sine Wave
Sine 0.1 / 0.05 / 0.02 Hz up to 24 kV RMS (VLF-34kV) or 31.8 kV RMS (VLF-45kV), plus DC ±5 kV and trapezoidal square-wave with auto slope matching cable capacitance. Detects water-trees in XLPE / PE and paper-insulated cables without damaging healthy insulation.
Frequency Matching
Auto Frequency Lock
Manual or automatic frequency 0.01 / 0.05 / 0.1 Hz matched to cable capacitance 1 nF–10 μF (VLF-34kV) or 1 nF–10 μF (VLF-45kV), with over-current auto-down-shift and test-voltage accuracy within ±1%.
Breakdown Detection
Real-Time Fault Trip
Real-time leakage-current monitoring with sub-cycle breakdown recognition, automatic HV disconnection, dedicated sheath testing to 10 kV DC with fault pinpointing, and trip-event logging aligned with IEC HD 620 / HD 621 S1.
Tan Delta
1x10⁻¹⁷ Accuracy
Automated three-tier voltage cycle (0.5 Uⁱ / 1.0 Uⁱ / 1.5 Uⁱ) captures tanδ, capacitance and insulation-resistance at every step; range 1×10⁻⁴—99.9×10⁻⁴, resolution 1×10⁻⁵, accuracy 1×10⁻⁴ for predictive-maintenance trending.
Data Logging
Onboard Report Export
Onboard storage of every test log with waveform capture, USB export of CSV / PDF reports, and PC software that batches A / B / C phase data into visual reports and curves. USB firmware updates extend field life.
Operator Safety
Dual Interlock + E-Stop
Emergency stop, dual-key HV interlock, reverse-voltage protection (13 kV / 15 kV), grounded discharge loop and over-current auto-down-shift satisfying EN 50191, VDE 0104 and GB/T 26860-2011.
Core Capabilities

Core Technical Features

All-in-One Ultra-Low Frequency Test Capabilities for Complete Medium-Voltage Cable Insulation & Sheath Diagnostics

Multi-Waveform Output
Sine / DC / Trapezoidal in One Unit

VLF-34kV delivers up to 24 kV RMS / 34 kV peak, VLF-45kV up to 31.8 kV RMS / 45 kV peak, plus ±5 kV DC and trapezoidal square-wave whose slope auto-adapts to cable capacitance. Withstand, tan-delta and leakage-current testing share one instrument.

Automated Tan-Delta
Three-Tier 0.5 / 1.0 / 1.5 Uⁱ Cycle

Automatic tan-delta cycle across 0.5 Uⁱ / 1.0 Uⁱ / 1.5 Uⁱ captures tanδ, capacitance and insulation-resistance data and grades the cable into light / moderate / severe degradation — no manual step-voltage tuning.

Sheath & Fleet
10 kV Sheath + Three-Phase Software

Dedicated sheath testing up to 10 kV DC with fault pinpointing, plus PC software that batches A / B / C phase readings into visual reports and curves. Real-time HV waveform and V/I display keep every test in view.

Intuitive UI Interaction
Device UI with kV/mA gauges and waveform
Automated test report with cable health assessment
Integrated Diagnostics

End-to-End Engineering

Full cable diagnostic workflow from on-site testing to data analysis & reporting

Multi-Waveform Withstand

VLF-45kV sine up to 31.8 kV RMS / 45 kV peak +VLF-34kV up to 24 kV RMS / 34 kV peak
DC output ±5 kV (VLF-45kV) / ±4 kV (VLF-34kV)
Trapezoidal square-wave with slope auto-matched to cable capacitance
Voltage resolution 0.001 kV + accuracy ±1% + 22 kg Peli Case 430×400×400 mm

Automated Tan-Delta Cycle

Automatic cycle at 0.5 Uⁱ / 1.0 Uⁱ / 1.5 Uⁱ captures tanδ / capacitance / insulation-resistance
Fixed test frequency 0.1 Hz +range 1×10⁻⁴—99.9×10⁻⁴ +resolution 1×10⁻⁵ +accuracy 1×10⁻⁴
Manual / automatic output frequency 0.01 / 0.05 / 0.1 Hz selection
Load range 1 nF–10 μF (VLF-34kV) / 1 nF–10 μF (VLF-45kV) + current 0— mA / 1 μA / ±1%

Breakdown & Sheath Protection

Real-time leakage-current monitoring with sub-cycle breakdown recognition
Sheath testing up to 10 kV DC + fault pinpointing on the cable outer sheath
Emergency stop +HV interlock +redundant grounding watch-dog

Technical Specifications

Complete electrical and mechanical specification overview

ParameterVLF-34kVVLF-45kV
General
Power Consumptionmax. 300 VAmax. 400 VA
Reverse Voltage Protection13 kV15 kV
Data InterfaceUSB 2.0USB 2.0
Dimensions (W x H x D)Peli Case 430 x 240 x 340 mmPeli Case 430 x 240 x 340 mm
Weight22 kg22 kg
Ambient Temperature (Operating)-10 °C to +50 °C-10 °C to +50 °C
Storage Temperature-20 °C to +60 °C-20 °C to +60 °C
ParameterVLF-34kVVLF-45kV
Output Voltage
Output Voltage (Sine Wave)max. 24 kV RMS (34 kV PEAK)max. 31.8 kV RMS (45 kV PEAK)
DC Voltage±1–34 kV±1–45 kV
Resolution0.001 kV0.001 kV
Accuracy1%1%
ParameterVLF-34kVVLF-45kV
Output Current
Measurement Range0–14 mA0–14 mA
Resolution1 μA1 μA
Accuracy1%1%
Maximum Capacitance Load0.1 Hz @ 0.5 μF / 24 kVrms / 34 kVpeak
0.05 Hz @ 1.0 μF / 24 kVrms / 34 kVpeak
0.01 Hz @ 8.0 μF / 18 kVrms / 25 kVpeak		0.1 Hz @ 0.5 μF / 31.8 kVrms / 45 kVpeak
0.05 Hz @ 1.0 μF / 31.8 kVrms / 45 kVpeak
0.01 Hz @ 5.0 μF / 22 kVrms / 31 kVpeak
ParameterVLF-34kVVLF-45kV
Dielectric Loss Factor Measurement
VLF-Sine1–24 kV rms1–31.8 kV rms
Load Range1 nF – 8 μF1 nF – 5 μF
Resolution1 × 10⁻⁻⁴1 × 10⁻⁻⁴
Accuracy1 × 10⁻⁴1 × 10⁻⁴
Measurement Range1 × 10⁻⁴ ∼ 9999.9 × 10⁻⁴1 × 10⁻⁴ ∼ 9999.9 × 10⁻⁴
tanδ Measurement Frequency0.1 Hz0.1 Hz
HV Safety Assurance

Security & Compliance

Multi-layer protection and conformity to global industry specifications

EN 50191 / VDE 0104 Operator Safety
Built-in emergency stop, dual-key HV interlock and grounded discharge loop satisfy EN 50191 and VDE 0104 operator-safety requirements for HV test equipment, with reverse-voltage protection to 13/15 kV.
CENELEC HD 620 / HD 621 Cable Testing
VLF withstand, tan-delta and leakage-current measurement procedures comply with CENELEC harmonisation documents HD 620 S1:1996 and HD 621 S1:1996 for medium-voltage cable insulation testing.
Sub-Cycle HV Disconnect
Real-time leakage-current monitoring with sub-cycle breakdown recognition and immediate HV disconnection protects the cable under test and the operator from arc-flash events.
GB/T 26852 / GB/T 26860-2011
Test procedures and operator-safety features aligned with GB/T 26852 and GB/T 26860-2011 Chinese power-industry standards for high-voltage testing operations.

Certifications

EN 50191 (operator safety)Compliant
VDE 0104 (HV test equipment)Compliant
HD 620 S1:1996 (cable testing)Compliant
HD 621 S1:1996 (cable testing)Compliant
CE LVD 2014/35/EUCompliant
CE EMC 2014/30/EUCompliant
GB/T 26852 (power industry)Aligned

Equip Your Crew with VLF-TD Tan Delta System?

Two-person certified operation +Peli-case portable for indoor, trench and outdoor use +firmware updates over USB +procedure templates for substation / utility / industrial cable commissioning.

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