Introduction to High Voltage Resonance Testing
As offshore and onshore power networks expand, so does the demand for reliable testing of high-voltage cables and terminations. To meet this growing need, Reynard High Voltage Solutions now offers offshore-ready resonance testing up to 72.5 kV AC, using the Mohaupt Variable Frequency Resonant Test Set (VFRTS72).
Housed in rugged 10-foot DNV-certified containers, this system delivers the accuracy, safety, and mobility required for the most demanding field environments — from offshore substations to onshore grid upgrades. Click here to read more about our High Voltage Testing Services.
What Resonance Testing Does
Resonance testing verifies the insulation integrity of high-voltage cables, joints, and terminations under operational voltage stress.
Unlike traditional test methods, resonance testing uses a tunable frequency system to minimize power demand while achieving full-voltage testing on long cable lengths. This makes it ideal for commissioning and maintenance of 66 kV and 72.5 kV networks.
The Mohaupt VFRTS72 System
The Variable Frequency Resonant Test Set (VFRTS) combines precision engineering and portability.
Each system includes:
- Oil-insulated, coreless reactors with high power and wide frequency range (10–300 Hz)
- OFAF cooling system for consistent performance up to 40 °C ambient temperature
- 72.5 kV / 56 A output (two reactors, master/slave operation)
- Compact 10′ DNV2.7-1 containers (5 t each) for offshore and transport compliance
- Integrated voltage dividers and safety interlocks per IEC 60060-3
- Digital control via PLC and optical fibre for safe, precise operation
This configuration allows testing of up to 12 µF at 10 Hz, making it suitable for long offshore export and array cables.
Reliable, Field-Proven Design
Each reactor container includes its own cooling and oil collection systems. All components are shock-proof up to 5 g and equipped with shock indicators — ensuring reliable performance under transport and offshore conditions.
Operation is managed from a remote panel or laptop up to 100 m away, minimizing operator exposure to high-voltage environments.
Why Choose Reynard for Resonance Testing
At Reynard, we combine technical precision with field experience.
- Over a decade of offshore wind expertise
- DNV-certified resonance test equipment for 66 kV – 72.5 kV systems
- On- and offshore deployment capability
- Supported by Reynard’s own testing specialists and certified jointers
We deliver peace of mind by ensuring every cable circuit is tested to the highest safety and performance standards before energization.
Resonance Test Specifications at a Glance
| Parameter | Specification |
| Test Voltage | 72.5 kV AC |
| Test Current | 56 A |
| Frequency Range | 10–300 Hz |
| Max Test Capacitance | 12 µF @ 10 Hz |
| Cooling | OFAF (Oil Forced Air Forced) |
| Container Type | 2 × 10′ DNV 2.7-1 |
| Weight per Container | 5 t |
| Operation | Master/Slave Configuration |
| Control | PLC + Remote HMI (Optical Fibre) |
Contact us
Whether you’re commissioning a 66 kV offshore wind farm or testing onshore transmission assets, Reynard’s resonance testing service provides portable, precision-controlled verification of your high-voltage cable systems.
Ensure your network is ready for operation — tested, verified, and documented to the highest standards.
Contact Reynard High Voltage Solutions to schedule a resonance test for your next offshore or onshore project.
