The Circutor Computer SMART III 6 (code R13851) is a three-phase power factor regulator for reactive energy compensation in low-voltage installations. It controls 6 capacitor-bank steps via contactor switching across a wide supply range of 100…520 V AC and communicates via RS-485 Modbus RTU. Current transformer inputs accept …/5 A or …/1 A secondaries, and the voltage measurement circuit covers 20…300 V phase-to-neutral.

Technical specifications:

• Model: Computer SMART III 6
• Circutor code: R13851
• EAN: 8433059175108
• Number of regulation steps: 6
• Switching unit: Contactor
• AC power supply: 100…520 V, 50…60 Hz
• Installation category: CAT III 300 V
• Power consumption: 10…16 VA
• Input current (CT secondary): …/5 A or …/1 A
• Phase current measuring range: 1…120% In
• Minimum current measurement: 50 mA
• Voltage measuring range: 20…300 V Ph-N, 35…520 V Ph-Ph
• Nominal voltage: 230 V Ph-N / 400 V Ph-Ph
• Minimum start voltage: 20 V Ph-N, 35 V Ph-Ph
• Frequency range: 45…65 Hz
• Leakage current measurement range: 0.01…1.5 A
• Digital relay outputs: 8 total (6 step outputs, 1 fan, 1 alarm relay); max 1 A / 1 kV; switching capacity 2500 VA
• Electrical life (relay): 30 x 10 cycles; mechanical life: 5 x 10 cycles
• Digital transistor outputs: 2 x NPN, 50 mA / 24 V DC
• Digital inputs: 2, optoisolated, potential-free contact
• Serial communication: Modbus RTU over RS-485
• Measurement accuracy – phase current: 0.5% +/- 1 digit; phase voltage: 0.5% +/- 1 digit; reactive power: 1% +/- 2 digit; active power: 0.5% +/- 2 digits; reactive energy: Class 1; active energy: Class 1
• Display: LCD Custom COG
• Keyboard: Capacitive, 5 keys
• Indicators: 4 LED
• Dimensions: 144 x 144 x 71 mm (W x H x D)
• Mounting: Panel
• Enclosure material: Plastic V0 self-extinguishing
• Weight: 0.57 kg
• Protection class: IP 51 (front panel), IP 31 (unmounted)
• Working temperature: -10…+55 C
• Storage temperature: -20…+70 C
• Relative humidity: 5…95% (non-condensing)
• Maximum installation altitude: 2000 m
• Standards: IEC 61010, IEC 61000-6-2, IEC 61000-6-4; measurements per IEC 61557-12

Features and benefits:

• Supports connection of either 1 or 3 current transformers, enabling accurate measurement in three-phase systems with significant load imbalances and allowing wiring changes without replacing the regulator.
• Integrated power analyser functions alongside reactive energy regulation, so a separate metering instrument is not required in the compensation panel.
• Residual leakage current monitoring (0.01…1.5 A) via WG series current transformers adds a safety monitoring layer directly within the capacitor bank controller.
• Up to 4 programmable cos-phi targets with separate time periods allows the unit to adapt to different tariff windows and compensation requirements without hardware modifications.
• Programmable alarms and built-in capacitor status testing routines support preventive maintenance and help identify capacitor degradation before failures occur.

Applications:

• Reactive energy compensation control in industrial and commercial low-voltage distribution panels with contactor-switched capacitor banks.
• Drop-in replacement for existing power factor regulators in any capacitor bank, owing to compatibility with both single-CT and three-CT measurement wiring.
• Installations with notable phase imbalances or multiple electricity tariff periods requiring flexible cos-phi target programming.
• Medium Voltage compensation units where broad supply voltage compatibility (up to 520 V AC) and RS-485 network integration are required.

Also known as: Circutor Computer SMART III 6, Computer SMART III 6 R13851, R13851 power factor controller, three-phase reactive energy regulator, capacitor bank controller RS-485.