North Guangjingyi GDAT-C2 Fully Automated Dielectric Loss and Resistivity Tester for Insulating Oils

Overview

The North Guangjingyi GDAT-C2 Fully Automated Dielectric Loss and Resistivity Tester is an integrated, microprocessor-controlled instrument engineered for precise, repeatable measurement of dielectric dissipation factor (tan δ), relative permittivity (ε_r), and DC volume resistivity (ρ) in liquid insulating media—primarily mineral and synthetic transformer oils, silicone fluids, and other high-resistivity dielectric liquids. It operates on the principles of guarded three-electrode capacitance bridge measurement under controlled thermal conditions, conforming to the fundamental test methodology defined in GB/T 5654–2007, which aligns closely with international standards including IEC 60247 and ASTM D924. The system integrates a temperature-regulated oil test cell, digitally synthesized AC/DC high-voltage sources, a stable SF₆-based reference capacitor, and a high-impedance electrometer—all housed within a single robust chassis. Its fully automated workflow eliminates manual intervention during voltage ramping, thermal equilibration, signal acquisition, and data computation, ensuring consistency across operator skill levels and laboratory environments.

Key Features

• Three-electrode test cell compliant with GB/T 5654–2007 and IEC 60247, featuring a fixed 2 mm electrode gap to minimize stray capacitance and surface leakage effects.
• Medium-frequency induction heating with closed-loop PID temperature control, enabling rapid, uniform, and contactless heating of the oil sample; temperature stability maintained within ±0.5 °C across the full 0–125 °C operating range.
• Internally mounted SF₆-filled three-terminal standard capacitor with inherently low temperature/humidity drift—ensuring long-term calibration integrity without field recalibration.
• AC test source architecture based on AC→DC→AC conversion, isolating measurements from line voltage fluctuations and frequency instability—even when powered by portable generators.
• Dual independent high-voltage subsystems: programmable 200–2200 V AC (50 Hz) for dielectric loss and permittivity, and 0–500 V DC for resistivity, each with overvoltage, overcurrent, and thermal fault protection.
• Onboard RAM9-based controller supporting real-time data acquisition, automatic null compensation, and built-in air-cell calibration to verify electrode cleanliness and mechanical alignment prior to sample testing.
• 5.7-inch full-color TFT capacitive touchscreen with intuitive Chinese-language interface, integrated real-time clock (RTC), and non-volatile storage for ≥1000 test records—including date/time stamp, test parameters, raw readings, and pass/fail flags.

Sample Compatibility & Compliance

The GDAT-C2 is validated for use with hydrocarbon-based insulating oils (e.g., naphthenic and paraffinic mineral oils), ester-based biodegradable fluids, silicone oils, and other non-conductive liquids with volume resistivity exceeding 10⁶ Ω·m. It supports routine quality control per transformer maintenance protocols (IEC 60429, IEEE C57.106) and acceptance testing per manufacturer specifications. Regulatory compliance includes adherence to GB/T 5654–2007 (Chinese national standard), IEC 60247 (international method for dielectric properties), ASTM D924 (standard test method for dielectric dissipation factor of electrical insulating oils), and ISO 6296 (petroleum products—determination of electrical resistivity). While not certified for FDA 21 CFR Part 11 or EU Annex 11 out-of-the-box, its audit-ready data logging (with immutable timestamps and parameter metadata) provides foundational traceability suitable for GLP/GMP-aligned laboratories implementing supplementary procedural controls.

Software & Data Management

The instrument’s embedded firmware implements deterministic measurement sequencing: auto-zeroing, thermal soak verification, AC excitation, phase-sensitive detection, DC voltage application, current integration, and final parameter derivation—all executed without user input after initial setup. Measurement results are stored locally with full context: operator ID (optional), ambient temperature/humidity (if external sensors connected), test voltage, temperature setpoint, measured tan δ, ε_r, ρ, and system diagnostic flags. Data export is supported via USB host port (CSV format), enabling direct import into LIMS or statistical process control (SPC) platforms. The system logs all critical events—including heater faults, HV interlock triggers, sensor disconnects, and calibration status changes—for internal diagnostics and quality review. No proprietary software installation is required for basic operation or data retrieval.

Applications

• Routine assessment of insulating oil condition in power transformers, reactors, and bushings per IEC 60429 and IEEE C57.106 guidelines.
• Acceptance testing of new oil batches against OEM specifications for dielectric loss and resistivity limits.
• Monitoring oxidative degradation, moisture ingress, and particulate contamination through trending of tan δ and ρ over time.
• Research and development of novel dielectric fluids, including natural esters and synthetic hydrocarbons, requiring high-precision permittivity and conduction characterization.
• Quality assurance in oil reclamation facilities, where post-regeneration resistivity and dissipation factor must meet ASTM D6802 or equivalent criteria.
• Calibration laboratory support for secondary standard oil verification, leveraging the GDAT-C2’s traceable measurement chain and air-cell validation capability.

FAQ

Does the GDAT-C2 require external calibration standards for daily use?
No. The integrated SF₆ reference capacitor and factory-traceable temperature sensor enable stable performance between scheduled annual calibrations. Air-cell verification before each test session satisfies intermediate verification requirements.
Can the instrument measure samples below 0 °C?
No. The minimum operating temperature is 0 °C, and the heating system is not designed for sub-zero conditioning. Samples must be brought to ambient or above prior to loading.
Is the test cell compatible with ASTM D924-compliant procedures?
Yes. The three-electrode geometry, 2 mm gap, and guard ring design fully satisfy the physical configuration requirements of ASTM D924, and the measurement algorithms implement the same calculation methods for tan δ and ε_r.
What happens if the oil temperature exceeds 120 °C during testing?
A redundant thermal cutoff relay de-energizes the induction heater at 120 °C ±2 °C, halting heating immediately and displaying a safety warning—preventing thermal decomposition of the sample or damage to the cell.
How is data integrity ensured during power interruption?
All measurement data is written to non-volatile memory before display refresh; partial test sequences are aborted safely, and no corrupted records are saved. The RTC maintains time continuity across power cycles.