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- Description
- Specifications
- Applications
- Advantages
- FAQ
- Recommended Products
Description
The GDTF-200kVA/200kV is a metrology-grade, field-optimized inductance-tuned power frequency resonant test system exclusively designed for error verification and AC withstand voltage test of 110kV-220kV capacitor voltage transformers (CVT). It fully complies with JJG 1021-2007《Verification Regulation for Instrument Transformers》 and IEC 60044-5 standards, adopting the series resonance principle to generate high voltage with only a small input power, while maintaining a pure 50Hz sine wave output identical to the grid frequency.
Unlike variable frequency resonant systems, this device adjusts reactor inductance to achieve resonance at fixed 50Hz, completely eliminating the frequency-dependent ratio error inherent in CVTs (which operate near series resonance internally). The system consists of a digital intelligent control box, an excitation transformer, a 330H-630H continuously adjustable dry-type epoxy-cast reactor, and a 0.2-grade standard capacitor voltage divider. Equipped with an electric servo tuning system and advanced automatic resonance finding algorithm, it can automatically adjust the reactor inductance to match the CVT's main capacitance (0.005μF-0.02μF) and achieve resonance within 60 seconds. With comprehensive safety protection and a dedicated interface for transformer calibrators, it ensures accurate and safe CVT verification in both laboratory and field environments.
Specifications
|
Parameter |
Specification |
|
Input Power |
3-phase 380V±10%, 50Hz |
|
Rated Output Capacity |
200kVA |
|
Rated Output Voltage |
0–200kV AC (RMS) |
|
Rated Output Current |
1A |
|
Output Frequency |
Fixed 50Hz±0.01% (pure power frequency) |
|
Output Waveform Distortion (THD) |
≤0.3% |
|
Reactor Type |
Dry-type epoxy-cast adjustable reactor (air gap) |
|
Inductance Adjustment Range |
330H–630H (continuous stepless) |
|
Adjustment Method |
Electric servo motor drive |
|
Matching CVT Main Capacitance |
0.005μF–0.02μF |
|
System Quality Factor (Q) |
≥30 (typical 30–40) |
|
Voltage Measurement Accuracy |
≤±1.0% F.S |
|
Current Measurement Accuracy |
≤±1.0% F.S |
|
Calibrator Interface |
BNC (voltage/current output) |
|
Test Modes |
Automatic calibration, Manual test, Timed withstand |
|
Timing Range |
0–9999s adjustable |
|
Display |
7-inch color touch screen |
|
Data Storage |
1000 groups (with time stamp) |
|
Data Export |
USB flash drive |
|
Protection Functions |
Zero-start, Over-voltage, Over-current, Flashover, Emergency stop, Ground detection, Over-temperature |
|
Continuous Operation Time |
5 minutes at full load |
|
Operating Temperature |
-10℃ ~ +40℃ |
|
Operating Humidity |
≤85%RH (non-condensing) |
|
Compliance |
JJG 1021-2007, GB 50150-2016, GB/T 16927.1-2011, IEC 60044-5, IEC 61010-1 CAT III 1000V |
Applications
Core Test Objects (110kV-220kV System)
- Capacitor Voltage Transformers (CVT): ratio error and phase error verification (primary standard)
- CVT AC withstand voltage test: power frequency withstand test after overhaul or commissioning
- Electromagnetic Voltage Transformers (VT): 110kV-220kV VT calibration and withstand test
- Current Transformers (CT): indirect calibration with standard voltage transformers
- Power transformers: 110kV-220kV transformer winding AC withstand test
- GIS & switchgear: 110kV-220kV GIS and switchgear insulation test
Typical Usage Scenarios
- Power metrology institutes: CVT and VT laboratory calibration and traceability
- Substation commissioning: new CVT acceptance test according to GB 50150-2016
- Preventive maintenance: periodic CVT error verification and insulation test
- Transformer manufacturers: factory calibration and quality control of CVTs
- Third-party inspection: compliance testing and certification of instrument transformers
Advantages
Pure 50Hz±0.01% Metrology-Grade Output
Identical to grid frequency, no frequency-dependent ratio error → fully complies with JJG 1021-2007 CVT calibration requirements
≤0.3% Ultra-Low Waveform Distortion
Excellent waveform quality ensures accurate error measurement → meets the strictest metrology standards
Wide Inductance Adjustment Range
330H-630H continuous adjustment matches all 110kV-220kV CVT main capacitances (0.005μF-0.02μF) → one system covers all mainstream CVT models
Electric Automatic Tuning
One-click auto tuning finds resonance point within 60 seconds → eliminates manual tuning, improves calibration efficiency
Dedicated Calibrator Interface
Seamless connection with all mainstream transformer calibrators → integrated CVT error measurement system
Safe Breakdown Protection
Short-circuit current after breakdown is only 1/Q of test current → prevents expensive CVT damage during test
FAQ
Q: Why can't variable frequency resonant systems be used for CVT calibration?
A: CVTs contain internal compensation reactors and operate near series resonance to achieve high accuracy. Their voltage ratio is extremely sensitive to frequency changes (a 0.1Hz frequency deviation can cause >0.1% ratio error). JJG 1021-2007 explicitly requires CVT calibration to be performed at 50Hz±0.5Hz, which only inductance-tuned power frequency resonant systems can meet.
Q: What is the difference between GDTF-200kVA/200kV (CVT) and GDTF-200kVA/50kV (general)?
A:
- GDTF-200kVA/200kV (CVT): 200kV output, 330H-630H inductance range, ≤0.3% THD, ±0.01% frequency stability, dedicated calibrator interface, optimized for CVT metrology
- GDTF-200kVA/50kV (general): 50kV output, 40H-102H inductance range, ≤0.5% THD, for general insulation tests
Both use inductance-tuned power frequency resonance technology.
Q: What CVT models can this system test?
A: It can test all 110kV and 220kV CVT models with main capacitance between 0.005μF and 0.02μF, which covers more than 95% of CVTs in operation worldwide.
Q: How long does it take to find the resonance point?
A: The electric automatic tuning system can find the precise resonance point at 50Hz within 60 seconds for any CVT in the matching range.
Q: Does it support connection with transformer calibrators?
A: Yes. It has a dedicated BNC interface that provides accurate voltage and current signals, compatible with all mainstream transformer calibrators on the market.
