XZ-3 ：Advanced Wireless Three-Phase Sequence Detection and Phasing Verification in High-Voltage Grids

The XZ-3 Wireless High-Voltage Digital Phase Sequence Meter represents a leap forward in high-voltage grid maintenance and safety. Designed for 6–220 kV systems, this device integrates wireless sensing, phase-sequence analysis, and phasing verification into a single platform. This paper examines its technical architecture, operational principles, and field applications, with a focus on its role in enhancing safety and efficiency for live-line working (LLW) and grid diagnostics.

1. Introduction
Three-phase sequence verification and phase-angle synchronization are critical in HV grid operations. Traditional methods require direct contact or complex insulated tools, posing safety risks and operational inefficiencies. The XZ-3 addresses these challenges through wireless, non-contact measurement, enabling real-time phase analysis while maintaining safe clearance distances.

2. System Architecture
The XZ-3 comprises three RF-enabled transmitters (X, Y, Z) and a centralized receiver (Fig. 1). Each transmitter operates as a distributed sensor node, capturing:

Phase angle (Φ) with ≤10° accuracy

Frequency (f) with ±0.1 Hz precision

Voltage presence (via capacitive coupling, leakage <10 μA)

Key subsystems:

Transmitter Module:

Operating voltage: 6–220 kV (broadband coupling)

RF range: >130 m (ISM band, adaptive modulation)

Power: <0.1 W (Li-ion rechargeable, 8-h runtime)

Receiver Module:

Phase comparison: ΔΦ calculation (A-B-C pairwise)

Decision logic:

Phase sequence: 120° ±10° tolerance for ABC/CBA determination

Phasing: ΔΦ <30° (in-phase), ΔΦ ≥30° (out-of-phase)

HMI: LCD with voice synthesis for hazard alerts

3. Technical Innovations
3.1 Wireless Synchronization
Proprietary time-division multiplexing ensures μs-level synchronization across transmitters, critical for sub-cycle phase comparisons. This eliminates GPS dependency while maintaining <1° RF-induced phase error.

3.2 Adaptive Noise Immunity
Field tests demonstrate reliable operation in 95% RH and -35°C to +45°C environments. DSP algorithms reject corona discharge interference (common in 220 kV+ lines).

3.3 Safety Compliance
Meets IEC 61481-2014 for live working and IEC 61243-1 for voltage detection. Dual insulation (transmitter clamps) and <10 μA leakage ensure Category IV (CAT IV) 300V safety.

4. Operational Workflows
4.1 Phase Sequence Verification

Deploy transmitters on L1, L2, L3 (clamp-on or bare conductor mode)

Receiver computes vector differences:

If Φ(L1-L2)=120°, Φ(L2-L3)=120° → "ABC" sequence

If Φ(L1-L2)=240°, Φ(L2-L3)=240° → "CBA" sequence

Voice alert for misphasing (>30° deviation)

4.2 Phasing Verification (Parallel Feeder Checks)
ΔΦ tolerance tightened to ±15° for synchronization tasks, with color-coded LCD indicators (green: <15°, amber: 15–29°, red: ≥30°).

5. Field Performance
Data from 220 kV substation trials (n=150 measurements):

6. Maintenance Integration

Transmitter IP67 rating enables storm condition use.

Cloud-enabled variants (XZ-3Pro) support SCADA integration via IEC 61850-7-2.

Automatic self-test: Validates RF link integrity and battery health (6.5 kg total weight allows crew-portable deployment).
The XZ-3 redefines HV phasing diagnostics by merging wireless precision with rigorous safety protocols. Its ≤10° phase accuracy and 130-m range enable rapid decision-making in live-line environments, reducing outage risks by 63% (per CIGRE study benchmarks). Future iterations may incorporate LiDAR alignment and partial discharge sensing for holistic grid asset management.

GDZX is a manufacturer of power testing equipment, offering a wide range of product categories with comprehensive models and providing professional technical support. Contact: +86-17396104357.Website: https://www.highvoltage-testequipment.com/