Power calibration and test bench UHV(H)

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Product introduction
The UHV(H) AC series inductance‑adjustable series resonance test system is designed for on‑site calibration and power‑frequency withstand testing of capacitive voltage transformers (CVTs) and electromagnetic transformers up to 500 kV. The compact system integrates an AC power source, excitation transformer and high‑voltage reactor to enable field tuning and operation at 50 Hz.

Fundamental principle
Power‑frequency resonance can be applied in series or parallel form. By compensating reactive power, the input apparent power required after full compensation can be reduced to 1/Q or less of the test output, allowing generation of high test voltages with limited input capacity.

Technical parameters

• Rated capacity: 80 kVA
• Rated voltage: 160 kV
• Adjustable inductance range: 65–130 H
• Rated frequency: 50 Hz
• Rated current: 0.5 A
• Adjustable gap range: 0–300 mm

Main functions

• Voltage boosting: series resonance circuit converts low‑voltage input into high‑voltage test output.
• Output stabilization: resonant tuning enables regulated voltage within the required range.
• Protection features: overvoltage, overcurrent and short‑circuit protection to isolate faults.
• Field adjustment: inductance and gap tuning for matching different CVT and site conditions.
• Wide applicability: suitable for power‑frequency testing of power systems, transformers and power‑electronic equipment.

Application scenarios

• New cable acceptance tests to verify insulation after laying.
• Substation expansion or refurbishment: withstand testing of GIS, breakers and transformers.
• Preventive testing during power plant overhaul (stator windings).
• On‑site testing of long collection lines for rail and wind‑farm projects.

Advantages

• Efficient high‑voltage generation with limited input power requirement.
• Simplified mechanical design for reduced maintenance in field operations.
• Rapid tuning and stable output for reliable on‑site calibration tasks.

Limitations

• Requires precise control of input frequency and amplitude due to resonance sensitivity.
• High‑voltage components must meet strict dielectric specifications for safe operation.

Common Q&A

• Q: What is series resonance and its benefit? A: Series resonance occurs when inductive and capacitive reactances balance, minimizing impedance and enabling high test voltages with smaller installed capacity.
• Q: Is series resonance safe to use? A: It is a technical method with advantages and risks; correct tuning and protections are required to avoid equipment or grid impact.
• Q: How to avoid harmful resonance? A: Modify circuit parameters (L, C, frequency) or add damping elements; use protective relays and controlled ramping.
• Q: Series vs parallel resonance? A: Series resonance minimizes impedance and maximizes current; parallel resonance maximizes impedance and minimizes current, so application differs.

Documentation

• Operation manual, wiring diagrams and calibration certificate available on request (PDF).