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Streamlined Capacitance Current Measurement: The ZX-CA Tester Advantage
Introduction: The Capacitive Current Challenge
In ungrounded or high-impedance grounded distribution systems (common in 10kV/35kV networks), a single-phase-to-ground fault results in capacitive current flow through the line-to-ground capacitance. Excessive capacitive current prevents arc self-extinction, significantly increasing the risk of equipment damage, network instability, and safety hazards. Chinese regulations mandate installing arc suppression coils when capacitive currents exceed 30A (10kV) or 10A (35kV). Accurate measurement is therefore critical, but traditional methods pose significant challenges.
Traditional Measurement Limitations
Conventional techniques often require accessing the primary system (high-voltage side). This necessitates complex safety protocols (work permits, isolation, grounding), extended downtime for scheduling, and carries inherent risks for personnel and equipment. Methods like injecting test signals directly onto live HV lines or capacitor bank switching are cumbersome and potentially hazardous.
The ZX-CA Solution: Safe, Fast, and Accurate Secondary-Side Measurement
The ZX-CA Automatic Capacitance Current Tester revolutionizes this process by enabling direct measurement exclusively from the secondary side of the system's Voltage Transformers (PTs), eliminating primary-side interaction and its associated risks.
Key Features & Advantages of the ZX-CA:
Exclusive Secondary-Side Operation: The tester connects solely to the PT's open-delta (broken-delta) secondary terminal. There is no need to access or interfere with the primary high-voltage circuits.
Enhanced Safety: By avoiding the primary system, testing becomes inherently safer. Technicians are not exposed to HV risks. Complex safety grounding procedures and lengthy outage scheduling are eliminated.
Simple Connection: Measurement setup involves simply connecting the test leads to the PT's open-delta terminal. Deployment is rapid, often taking minutes.
Intelligent Signal Injection: The ZX-CA injects a weak, inter-frequency test signal into the open-delta circuit. This signal is specifically chosen to:
Avoid Interference: It sits outside the standard 50/60 Hz power frequency band, preventing disruption to protective relays and metering.
Ensure Immunity: The instrument and PT are inherently immune to interference from the 50 Hz system voltage and currents.
Guarantee Safety: The output stage is designed to withstand up to 100V AC. Even if a genuine single-phase ground fault occurs during the test, the PT and the tester remain protected.
Efficiency & Accuracy: Tests are completed quickly and safely. Results are highly accurate (≤5% error), stable, and reliable, providing the essential data for compliance verification and arc suppression coil sizing.
Technical Specifications (ZX-CA):
Measurement Range:
Capacitance: 0.3 µF to 125 µF
Capacitive Current: 1 A to 250 A
Accuracy: ≤ 5%
Output Withstand: 100V AC (Protects against system faults during test)
Power Supply: AC 220V ± 20%, 50Hz ± 5Hz
Environmental: -10°C to 50°C, ≤85% RH
Dimensions: 345mm x 295mm x 175mm
Weight: 5kg
The ZX-CA Advantage: A Clear Comparison
Feature | Traditional Methods | ZX-CA Tester |
Access Point | Primary Side (High Voltage) | Secondary Side (PT Open-Delta) |
Safety Risk | High (HV Exposure) | Very Low (LV Only) |
Safety Prep | Complex (Permits, Grounding, Isolation) | Minimal to None |
Scheduling | Often Requires Outages/Long Waits | Can Usually Be Done Live, Rapidly |
Connection | Complex, Primary Disconnection Often Needed | Simple (Connect to PT Terminal) |
System Impact | Risk of Relay Misoperation/Disruption | None (Uses Immune Inter-Frequency Signal) |
PT/Device Risk | Potential During Faults/Testing | Protected (100V AC Withstand) |
Speed | Slow | Fast (Minutes) |
Ease of Use | Difficult, Requires HV Expertise | Simple, Safer Operation |
For power utilities and technicians responsible for maintaining ungrounded or compensated distribution networks, accurately measuring system capacitive current is a non-negotiable requirement for safety and reliability. The ZX-CA Automatic Capacitance Current Tester provides a paradigm shift. By leveraging the PT's open-delta secondary connection and employing intelligent inter-frequency signal injection, it delivers accurate, reliable results with unprecedented levels of safety and operational efficiency. It eliminates the dangers and complexities associated with primary-side access, transforming a traditionally high-risk, time-consuming task into a safe, simple, and rapid procedure essential for ensuring network compliance and protection.
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/
