Performance and Application of ZXHQ-Y CT/PT Field Calibrator for Power System

Abstract

Current transformers (CT) and voltage transformers (PT) act as key sensing components in power grids, undertaking measurement, metering and relay protection tasks. Their electromagnetic characteristics directly determine the safety and accuracy of power system operation. Accurate on-site characteristic testing of CT and PT is essential for equipment commissioning, routine maintenance and fault diagnosis. This paper introduces the ZXHQ-Y Transformer Field Calibrator, a multifunctional CT & PT characteristic tester developed to comply with international and domestic standards, elaborates its testing functions, core technical specifications and practical engineering application scenarios for power engineering technicians’ reference.

1. Introduction

In high-voltage power systems, the operating performance of instrument transformers has a critical influence on protection action and energy metering. Saturated excitation, winding defects, incorrect wiring and load mismatch will cause measurement deviation and even protection malfunction. Traditional separate testing instruments cannot complete comprehensive parameter acquisition efficiently on site. The ZXHQ-Y Transformer Field Calibrator is designed in accordance with IEC60044-1, IEC60044-2, IEC60044-6, GB1207, GB1208, GB16847 and IEEE C57.13 standards. The device can fully acquire excitation characteristics, winding parameters and error indicators of both CT and PT. Its maximum equivalent inflection point voltage for CT testing reaches 45 kV, which meets the testing requirements of most instrument transformers used in transmission and distribution networks.

2. Main Testing Functions of ZXHQ-Y Calibrator

This integrated CT/PT analyzer realizes comprehensive testing for current transformers and voltage transformers respectively.

2.1 Test Items for Current Transformers (CT)

Excitation characteristic test

Turn ratio detection

Ratio difference and phase angle difference verification

Polarity inspection

Secondary winding resistance measurement

Secondary load measurement

5% and 10% error curve testing

Transient characteristic test and analysis

Automatic inference of CT nameplate parameters

Measurement of key CT parameters: inflection point voltage/current, accuracy limit factor (ALF), instrument security factor (FS), secondary time constant, remanence coefficient, saturation characteristic, inductance, inflection point electromotive force, limit electromotive force and area factor

Hysteresis loop measurement of CT iron core

2.2 Test Items for Voltage Transformers (PT)

PT turn ratio detection

PT polarity verification

PT secondary winding resistance measurement

PT secondary load measurement

3. Core Technical Specifications

The key technical indicators of ZXHQ-Y guarantee reliable precision for field testing:

Power supply: AC220V ±10%, 50Hz/60Hz ±10%

Output range: AC voltage 0.1 ~ 125 V; output current 0.001 ~ 5 A (RMS); maximum output power 300 VA

Maximum equivalent inflection point test voltage: 45 kV

Measurement precision

Current measurement: 0 ~ 10 A auto-range, measuring error ≤ ±0.1% + 0.01% FS

Voltage measurement: 0 ~ 200 V auto-range, measuring error ≤ ±0.1% + 0.01% FS

Turn ratio measuring range: 1 ~ 30000

Phase measurement accuracy: ±2 minutes, resolution up to 0.01 minute

Secondary winding resistance: 0 ~ 8 kΩ auto-range, resolution 0.1 mΩ

Data storage: Support storage of more than 1000 groups of test data

Operating environment: Ambient temperature -10 ℃ ~ 50 ℃, relative humidity ≤90%

Physical dimension: 485mm × 356mm × 183mm, total weight:15 kg

4. Typical Engineering Application Scenarios

The ZXHQ-Y field calibrator is widely applicable in power station commissioning, substation maintenance and power grid equipment troubleshooting. Main application scenarios include:

Parameter verification according to CT nameplate data

Parameter inspection under actual secondary load of CT

Analysis on how CT transient characteristics affect relay protection equipment

Verification and calibration of PT nameplate parameters

Field test and assessment of PT secondary load

During equipment handover acceptance and periodic maintenance, technicians can use this single unit to complete all conventional and characteristic tests of instrument transformers. Compared with discrete testing equipment, it greatly shortens on-site working time and avoids repeated wiring operations. The acquired excitation curve, hysteresis loop and saturation parameters provide quantitative data support for evaluating whether CT can meet the requirement of transient protection.

5. Conclusion

With the continuous development of smart grids, higher requirements are put forward for the on-site testing accuracy and functional integration of instrument transformer test equipment. The ZXHQ-Y Transformer Field Calibrator integrates multi-dimensional testing capabilities of CT and PT. Supported by standard-compliant design and stable measurement accuracy, it can obtain complete electromagnetic characteristic parameters of instrument transformers. In engineering practice, the tester can effectively identify hidden defects such as iron core aging, remanence saturation and secondary circuit abnormality. It serves as practical testing equipment for substation commissioning, power equipment preventive test and power grid fault analysis, and offers reliable technical support for stable and safe operation of power transmission and distribution systems.

GDZX is a manufacturer of power detection equipment, offering a diverse range of products with comprehensive models and providing professional technical support. Contact us at +86-27-6552607 or +86-17396104357.Website: http://en.gdzxdl.com/