Frequency response analyzer UHV-312

3-phase electrical networksfor single-phase electrical networksfor testing

Overview
The UHV-312 is a sweep frequency response analyzer designed for diagnostic testing of transformer windings. It supports frequency-response (sweep) and low-voltage short-circuit impedance methods, stores test results in a database and includes an inductance measurement function. The instrument is adapted for on-site use and compatible with modern Windows platforms.

Product parameters
The UHV-312 is engineered for large and medium transformers. It uses high-precision synchronous AC sampling and FFT digital signal processing for voltage and current to deliver stable, repeatable measurements. Supports three-phase automatic measurement or single-phase testing with reliable short-circuit on the low-voltage side. After entering transformer parameters the instrument automatically tests and calculates impedance and impedance error percentage per phase. Real-time voltage and current waveform display aids field diagnostics.

Technical parameters

• Measuring speed: single-phase winding 1–2 minutes
• Output voltage (impedance method): up to 20 Vpp (auto-adjust)
• Output impedance: 50 Ω
• Input impedance: 1 MΩ (response channel with 50 Ω matching resistor)
• Sweep range: 100 Hz – 2 MHz
• Frequency accuracy: 0.005%
• Sampling frequency: 100 MSPS
• Sweep mode: linear or logarithmic; frequency points configurable
• Curve display: amplitude–frequency curve; oscilloscope view for voltage/current
• Dynamic measurement range: −120 dB to 20 dB
• Impedance method voltage range: 0–220 V
• Impedance method current range: 0–10 A
• Impedance test frequency: 50 Hz / 60 Hz

Features

• Frequency-response sweep measures winding characteristics without removing the transformer cover, enabling accurate detection of deformation, bulging or axial displacement (suitable for transformers ≥66 kV).
• Fast measurement: 1–2 minutes per winding (single-phase).
• High frequency accuracy (0.005%) and wide dynamic range for detailed analysis.
• 5000 V isolation protection to safeguard the testing computer.
• Built-in oscilloscope function for real-time monitoring of test conditions.
• Simultaneous loading of up to 9 curves with automatic parameter calculation and diagnostic comparison.
• Analysis software compliant with DL/T911-2016 and IEC60076-18 standards.
• Short-circuit impedance method operates without an external voltage regulator and can automatically apply voltage to AB/BC/CA high-voltage windings, synchronously collect data and compute impedance error percentages.
• Database storage of test data and automatic export to Word (if Office installed) or JPG reports for convenient reporting.
• Inductance measurement capability integrated.
• Intuitive software with one-key measurement operation to simplify on-site workflows.

Technical specifications

• Model: UHV-312
• Sweep range: 100 Hz – 2 MHz
• Frequency accuracy: 0.005%
• Sampling frequency: 100 MSPS
• Measuring speed: single-phase winding 1–2 minutes
• Output voltage (impedance method): up to 20 Vpp (auto-adjust)
• Output impedance: 50 Ω
• Input impedance: 1 MΩ (response channel with 50 Ω matching)
• Sweep modes: linear or logarithmic; sweep frequency and points configurable
• Display: amplitude–frequency curve and oscilloscope waveforms
• Dynamic measurement range: −120 dB to 20 dB
• Impedance measurement ranges: voltage 0–220 V, current 0–10 A
• Impedance test frequency: 50 Hz / 60 Hz
• Isolation protection: 5000 V
• Software/platform: database storage, automatic report generation (Word/JPG), compatible with Windows 2000/XP/7/8/10/11
• Standards: DL/T911-2016, IEC60076-18

Purpose of the experiment

• Winding deformation is a major hidden danger to the safe operation of power systems. In recent years, with the increase of power system capacity, short-circuit capacity has also been continuously increasing, and winding damage accidents caused by outgoing short circuits have also shown an upward trend.
• After the transformer winding deforms, the first thing that happens is a change in insulation distance or damage to the insulation paper. When encountering overvoltage, the winding will experience inter disc or inter turn breakdown, or under long-term operating voltage, insulation damage will gradually expand, ultimately leading to the transformer. Damage: Secondly, mechanical performance decreases after winding deformation. When a short circuit accident occurs again, an immediate damage accident will occur due to the inability to withstand the huge impact force, and it can still operate for a period of time.
• Transformer winding deformation is one of the important causes of transformer damage. Conventional electrical tests such as resistance measurement, ratio measurement, and capacitance measurement are difficult to detect winding deformation, which will seriously threaten the safe operation of the power grid. Therefore, it is necessary to detect and diagnose the deformation of transformer windings subjected to mechanical and electric forces.