WattNode Modbus - Modbus Power and Energy Meters

Diagnostic LEDs

Our diagnostic LEDs provide a per-phase indication of power (green flashing) and negative power (red flashing) to help troubleshoot connection problems, like reversed CTs, or excessive line voltage. The WattNode Modbus meter also has a red/yellow/green communication LED to indicate traffic, configuration problems, bus contention and other conditions. See the manual for full descriptions.

Measurements

• Supports floating point and integer registers
• True RMS Power: Watts (Phase A, B, C, and sum of all phases)
• Reactive Power: VARs (Phase A, B, C, and sum of all phases)
• Power Factor: (Phase A, B, C, and sum of all phases)
• True RMS Energy: Kilo-Watthours kWh (Phase A, B, C, and sum of all phases)
• Reactive Energy: kVAR-hours (All Phases)
• AC Line Frequency
• RMS Voltage: (Phase A, B, C)
• Computed RMS Current: (Phase A, B, C)
• Demand
• Peak Demand

Features

• Small form factor for easy installation inside most electrical panels, see a sample installation diagram
• Pluggable screw terminals for easy wiring
• 0.5% accuracy nominal (see manual for details)
• True RMS power even with leading or lagging power factor and chopped or distorted waveforms
• Measure variable speed drive pumps and motors
• Uses safe CT`s (current transformers), output 0.333 Vac at rated current.
  • Split core CTs for quick installation
  • Solid core CTs are less expensive and prevent tampering
  • Bus bar CTs for high current applications (standard and custom sizes)
• UL, cUL Listed - Designed and tested for safety and use throughout North America.
• Assembled in USA, qualified under the Buy American provision in the American Recovery and Reinvestment Act of 2009 (ARRA).
• Five year warranty

Modbus Communication

• Protocol: Modbus RTU (binary)
• Baud Rates: 2,400, 4,800, 9,600,19,200, and 38,400 baud
• Duplex: Half (two-wire plus common)
• Parity (default): N81 (no parity, eight data bits, one stop bit)
• Modbus Buffer: 256 bytes
• Response Time (typical): 5 to 25 milliseconds

EIA RS-485 Interface

• Driver Output Voltage (Open Circuit): ± V maximum
• Driver Output Voltage (54Ω load): ± 1.5 V minimum
• Driver Output Current (54Ω load): ± 60 mA typical
• Driver Output Rise Time (54Ω || 50 pF load): 900 nS typical
• Receiver Common-Mode Voltage Range: –7 to +12 Vdc maximum
• Receiver Sensitivity: ±200 mV
• Receiver Bus Load: 1/8 unit load

Electrical

• Line powered
• Operating Voltage Range: –20% to +15% of nominal
• Power Line Frequency: 50 or 60 Hz
• CT Input: 0.333 Vac nominal, 0 to 0.5 Vac operating, 3 Vac maximum

Measurement Configurations

Models available for:

• Single phase: two or three wire
• Three phase: four wire wye
• Three phase: three wire delta
• Three phase: four wire delta

Accuracy

WattNode Modbus

• 0.5% nominal (see manual for details)

WattNode Revenue Modbus

• 0.5% nominal (see manual for details)
• Meets the accuracy requirements of the ANSI C12.1 standard when used with CCS CTs rated for IEEE C57.13 class 0.6 accuracy (see Revenue Grade CTs).
• Models RWNC-3Y-208-MB, RWNC-3D-240-MB and RWNC-3Y-480-MB are certified by MET Laboratories to meet ANSI C12.1. MET Labs is a nationally recognized testing laboratory (NRTL).

Regulatory

• FCC Class B, EN 55022 Class B
• UL and cUL Listed (UL 61010-1), file number E312220
• CE Mark and RoHS
• Immunity: EN 61326: 2002 (Industrial Locations)

Environmental

• Operating Temperature: –30°C to +55°C (–22°F to +131°F)
• Altitude: Up to 2000 m (6560 ft)
• Operating Humidity: 5 to 90% relative humidity (RH) up to 40°C, decreasing linearly to 50% RH at 55°C.
• Pollution: POLLUTION DEGREE 2 - Normally only non-conductive pollution; occasionally, a temporary conductivity caused by condensation must be expected.
• Indoor Use: Suitable for indoor use.
• Outdoor Use: Suitable for outdoor use when mounted inside an electrical enclosure (Hammond Mfg., Type EJ Series) that is rated NEMA 3R or 4.

Mechanical

Case Dimensions

(Click on the image for a larger view.)

• Enclosure:
  • High impact, ABS plastic
  • Flame Resistance Rating: 94V-0, IEC FV-0
  • Size: 5.63 × 3.34 × 1.5 in. (143 × 85 × 38 mm)
  • Weight: 10.8 oz (305 g)
• Connectors: Euroblock style pluggable screw terminal blocks
  • Green: 22 to 12 AWG (1.0 to 3.2 mm), 600 V
  • Black: 22 to 12 AWG (1.0 to 3.2 mm), 300 V