ABB RVT-6 Automatic Power Factor Controller

The ABB RVT-6 (also designated RVT6) is a microprocessor-based automatic power factor regulator designed for medium and low voltage capacitor banks. It continuously monitors the power factor of an electrical installation and automatically switches capacitor stages to maintain the set target power factor, thereby reducing reactive energy penalties and improving transformer utilization. The RVT-6 offers 6 relay outputs for controlling capacitor contactors or thyristor switches.

Electrical Specifications

• Model: RVT-6 (RVT6)

• Supply Voltage: 100–440V AC (50/60 Hz)

• Measurement Input: 3-phase voltage and current (CT secondary: 5A or 1A)

• Number of Outputs: 6 relay outputs (5A, 250V AC)

• Communication: RS-485 Modbus RTU (standard)

• Display: Backlit LCD with 4 lines x 20 characters

• Measured Parameters: Power factor (cos φ), active power (kW), reactive power (kVAR), apparent power (kVA), voltage, current, frequency, THD (voltage and current)

• Control Strategy: Automatic or manual, linear or circular switching, 4-quadrant operation

• Protection: Overvoltage, undervoltage, overcurrent, overtemperature, harmonic overload

• Operating Temperature: -20°C to +60°C

• Enclosure Rating: IP51 (front panel), IP20 (rear)

Advanced Measurement and Analysis

The RVT-6 uses true RMS measurement with 16-bit resolution, sampling at 32 samples per cycle. It calculates total harmonic distortion (THD) up to the 31st harmonic for both voltage and current. This information helps diagnose power quality issues and can prevent capacitor bank damage due to harmonic resonance. The controller also logs minimum and maximum values for all parameters with timestamps, stored in non-volatile memory for up to 60 days.

Control Algorithms

The RVT-6 implements three switching strategies: linear (sequential), circular (rotating duty), and optimized (selects the optimal combination of stages). It can manage capacitor stages with different ratings (e.g., 10, 20, 30 kVAR) using an intelligent binary or thermometer code algorithm. The controller includes a learning function that measures the step size of each output during commissioning and adapts the control logic accordingly. A manual override mode allows forced switching of individual stages for testing.

Communication and Remote Monitoring

The built-in RS-485 port supports Modbus RTU protocol at baud rates up to 115,200 bps. This allows integration with building management systems (BMS), SCADA, or energy monitoring software. ABB offers free PC software (RVT Setup Tool) for parameter configuration, data logging, and firmware updates via the USB front port. Optional communication modules (PROFIBUS DP, Ethernet) are available as plug-in cards.

User Interface and Setup

The backlit LCD display shows real-time power factor, active power, and the status of each capacitor stage. Six front-panel buttons allow navigation through the menu system. The wizard-based setup guides the user through CT ratio, target cos φ, switching delay, and harmonic protection thresholds. Up to 50 different parameter settings can be saved and recalled for different operating modes (e.g., day/night).

Output and Alarm Relays

The six output relays are rated for 5A at 250V AC (resistive). Each relay can be configured for capacitor control, fan control, or alarm annunciation. Additionally, one dedicated alarm relay (SPDT) provides warning of abnormal conditions such as over-compensation, low power factor despite all stages ON, or communication loss. Relay status is indicated by LEDs on the front panel.

Physical Dimensions and Mounting

Dimensions: 144mm x 144mm (square) x 72mm depth. The controller mounts in a standard 138x138mm cutout (DIN 43700). It is suitable for panel mounting with four spring clips. Weight: 0.8 kg. The rear terminals accept wire up to 2.5mm² for power and CT inputs.

Standards and Certifications

The RVT-6 complies with IEC 61326-1 (EMC), IEC 61010-1 (safety), and IEC 60870-2-1 (environmental). It is CE marked and UL listed (File E199398). The controller also meets marine classification requirements (DNV GL, ABS) when specified.

Applications

Typical installations include industrial plants with varying loads (e.g., welders, compressors, crushers), commercial buildings with HVAC and lighting, and renewable energy systems (wind, solar). The RVT-6 is also used in utility substations for primary distribution capacitor banks.

Conclusion

The ABB RVT-6 power factor controller offers precise, automated reactive power compensation with advanced monitoring and communication capabilities, helping facilities reduce energy costs and meet utility requirements.