Project Overview
In April 2026, Wuhan Hongzhi Gaoce Electrical Technology Co., Ltd. Test engineers were invited by a regional power utility to perform SF6 density relay calibration at a thermal power plant during a scheduled maintenance outage.
The purpose of the project was to verify whether the alarm pressure, lockout pressure, alarm reset pressure, and lockout reset pressure of multiple SF6 density relays met the required operating values before the power plant returned to service.
Accurate calibration is essential to ensure the safe and reliable operation of SF6 circuit breakers and GIS equipment.
Customer Challenge
During planned maintenance, every SF6 circuit breaker must be inspected before being energized again.
The customer needed to:
- Verify the operating accuracy of multiple SF6 density relays.
- Record calibration results for future maintenance.
- Complete testing efficiently to avoid delaying the maintenance schedule.
Because the original factory settings for the installed relays were unavailable, accurate measurement and data recording were especially important.
Equipment Used
HKV Test engineers carried out the project using a professional SF6 Density Relay Calibration Tester, together with standard testing accessories and measuring instruments.
The equipment supports:
- Automatic pressure control
- Temperature compensation to 20°C
- Multiple automatic test cycles
- Alarm and lockout signal verification
- Automatic report generation and printing
Testing Procedure
After the maintenance team removed each SF6 density relay from the circuit breaker, HKV Test engineers connected the relay to the calibration instrument using dedicated adapters.
The tester automatically performed several charging and discharging cycles while monitoring:
- Alarm pressure
- Lockout pressure
- Alarm reset pressure
- Lockout reset pressure
The instrument automatically compensated the measured values to the standard reference temperature of 20°C and generated a complete test report for each relay.
After testing, all residual gas inside the connecting hoses was safely released before the relay was reinstalled.
The same procedure was repeated for every SF6 density relay on site.
Test Results
The calibration work was completed successfully during the scheduled maintenance period.
The project achieved:
- Accurate verification of multiple SF6 density relays
- Automatic generation of standardized test reports
- Improved maintenance efficiency through automated testing
- Reliable reference data for future inspections
The completed calibration helped ensure that the SF6 circuit breakers could safely return to operation after maintenance.
Customer Feedback
This project continued a long-term cooperation between HKV Test and the customer.
After several successful on-site testing projects, the customer expressed strong confidence in the performance of HKV Test equipment and the professionalism of the engineering team. Following the project, the customer planned to purchase additional electrical testing equipment used during previous maintenance work.
Why Accurate SF6 Density Relay Calibration Matters
SF6 density relays play a critical role in monitoring gas pressure inside GIS and SF6 circuit breakers.
Regular calibration helps:
- Improve equipment reliability
- Prevent false alarms
- Ensure correct lockout operation
- Support preventive maintenance
- Reduce unexpected outages
Frequently Asked Questions
Why should an SF6 density relay be calibrated?
Regular calibration verifies that alarm and lockout functions operate at the correct pressure values, ensuring safe operation of SF6 electrical equipment.
What parameters are checked during calibration?
Typical parameters include alarm pressure, lockout pressure, alarm reset pressure, and lockout reset pressure.
Why is temperature compensation necessary?
SF6 gas pressure changes with temperature. Converting results to the standard reference temperature of 20°C allows consistent evaluation.
Can multiple relays be tested in one maintenance project?
Yes. Professional calibration equipment allows efficient testing of multiple SF6 density relays during planned maintenance outages.
Is automatic report generation important?
Yes. Automatic reports improve traceability and simplify maintenance documentation.
Conclusion
Routine SF6 density relay calibration is an essential part of preventive maintenance for substations and power plants. By combining professional testing equipment with experienced field engineers, Wuhan Hongzhi Gaoce Electrical Technology Co., Ltd. helps customers verify relay performance, improve operational reliability, and support safe commissioning after maintenance.
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