1. Introduction and System Overview

The Shaft Current and Voltage Protection Relay (SCVP) system by KONČAR Electrical Engineering Institute is designed to monitor and protect generator bearings from damage caused by shaft currents and voltages induced by magnetic field asymmetry. The system measures shaft voltage and current, analyzes their harmonic composition, and provides protection through configurable alarms and relay outputs.

The SCVP system integrates real-time data acquisition, processing, and visualization via local Human-Machine Interface (HMI) and remote web applications accessible through standard internet browsers. It supports Ethernet connectivity and can be integrated with SCADA and other supervisory systems.

2. System Architecture and Features

• Measurement Inputs: Two-channel acquisition unit measuring shaft current (0 to ±50 mA) and voltage (0 to ±10 V) with high accuracy and frequency range up to 10 kHz.
• Protection: Spectral analysis (FFT) for harmonic detection, configurable alarms, and relay outputs (2 to 8 relays) for protection actions.
• Connectivity: Ethernet 10/100 with support for Modbus TCP, FTP, IEC 60870-104, HTTP protocols.
• User Interface: Local HMI with optional touch screen and remote web server for real-time data, trends, spectrum, and alarms.
• Data Management: Long-term data storage and historical trend analysis (available in advanced versions).
• Installation: Non-intrusive installation without machine interruption, integration with multiple power plants and user accounts.

3. Technical Specifications

Inputs

• Current Input: Measuring range 0 to ±50 mA, overload 300 mA, error <0.05 mA, input resistance 5 Ω, capacitance 1 nF.
• Voltage Input: Measuring range 0 to ±10 V, overload 250 V, error <10 mV, input resistance 1 MΩ, capacitance 500 pF.

Outputs

• 2 to 8 digital relay outputs, continuous current 6 A, max switching power 1500 VA, max voltage 250 VAC/DC.

Power Supply

• DC: 80 V to 370 V; AC: 85 to 264 V, 47 to 63 Hz; max power interruption 100 ms (230 VAC).

Environmental

• Operating temperature: -20°C to +70°C (standard), 0°C to +55°C (touch screen variant).
• Storage temperature: -40°C to +85°C.

Dimensions and Protection

• 19" rack installation: 482.5 x 177.5 x 250 mm.
• Cabinet IP54 standard, IP66 optional.

4. Measuring Sensors

• Instrument Transformer: For shaft current measurement, rated voltage 0.7 kV, insulation 3 kV, typical transfer ratio 1:1000, frequency 50/60 Hz.
• Sliding Brushes and Small CTs: For shaft voltage and current measurement, typical CT ratings 100 mA to 10 A.

5. Software and User Interface

The SCVP system software provides local and remote visualization of real-time data, including waveforms and spectral analysis. The local HMI is customizable and supports multiple languages. The embedded web server allows remote access from various devices (PCs, tablets, smartphones) without additional software installation, using standard browsers such as Chrome, Firefox, Safari, and Internet Explorer.

Advanced versions support long-term data archiving, trend analysis, and automated report generation for predictive maintenance.

6. Documentation and Support

Comprehensive documentation is provided, including:

• Mechanical documentation (Book I)
• Electrical documentation (Book II)
• User instructions (Book III)
• Initial state records (Book IV)
• Certificates and test reports (Book V)

7. Ordering Guide and Customization

The SCVP system is modular and customizable based on customer requirements:

• Versions: V1 (basic measurement and protection), V2 (adds 5.7" display and enhanced HMI), V3 (adds long-term data storage and historical data access).
• Inputs/Outputs: Options for shaft current only or combined current and voltage measurement; configurable number of digital and analog outputs.
• Sensors: Instrument transformer or sliding brush options for current and voltage measurement.
• Services: Documentation, installation, commissioning, user training, extended warranty, and periodic diagnostic reports.
• Installation Materials: Sensor holders, cables, and electrical cabinet or 19" rack housing options.

An example order includes specifying sensor types, number of inputs/outputs, SCVP version, documentation scope, installation materials, and housing type.

8. Benefits and Applications

The SCVP system is globally recognized and widely implemented on hydro and turbo generators. It provides reliable predictive monitoring to prevent bearing damage, ensuring operational safety and longevity of rotating machines.