Overview
5
Overview
Congratulations on your purchase of the WattNode
®
BACnet
®
watt/watt-hour transducer (meter).
The WattNode meter offers precision energy and power measurements in a compact package.
It is designed for use in demand side management (DSM), sub-metering, and energy monitor-
ing applications. The WattNode meter communicates on an EIA RS-485 two-wire bus using the
BACnet protocol. Models are available for single-phase, three-phase wye, and three-phase delta
configurations for voltages from 120 Vac to 600 Vac at 50 and 60 Hz.
The WattNode meter uses a half-duplex EIA RS-485 interface for communication. The standard
baud rates are 9,600, 19,200, 38,400, and 76,800 baud. The meter uses the industry standard
BACnet MS/TP communication protocol, allowing up to 64 devices per RS-485 subnet.
Option TM1
for the WattNode BACnet adds support for temperature measurement using an
external 10k thermistor. This allows the WattNode to measure an external temperature (ambient, a
motor, chilled water, etc.) ranging from -50°C to 150°C (depending on the thermistor).
Measurements
The WattNode BACnet meter measures the following:
●
True RMS Power - Watts (Phase A, Phase B, Phase C, Sum)
●
Reactive Power - VARs (Phase A, Phase B, Phase C, Sum)
●
Power Factor (Phase A, Phase B, Phase C, Average)
●
True RMS Energy - Watthours (Phase A, Phase B, Phase C, Sum)
●
Reactive Energy - VAR-hours (Sum)
●
AC Frequency
●
RMS Voltage (Phase A, Phase B, Phase C)
●
RMS Current (Phase A, Phase B, Phase C)
●
Demand and Peak Demand
One WattNode BACnet meter can measure up to three different “single-phase two-wire with neu-
tral” branch circuits from the same service by separately monitoring the phase A, B, and C values.
If necessary, you can use different CTs on the different circuits.
Diagnostic LEDs
The meter includes three power diagnostic LEDs—one per phase. During normal operation, these
LEDs flash on and off, with the speed of flashing roughly proportional to the power on each phase.
The LEDs flash green for positive power and red for negative power. Other conditions are signaled
with different LED patterns. See
Installation LED Diagnostics (p. 22)
The BACnet WattNode meter includes a communication LED that lights green, yellow, or red to
diagnose the RS-485 network. See
BACnet Communication Diagnostics (p. 27)
for details.
Options
The WattNode BACnet meter can be ordered with options. For more details and documentation,
see
https://ctlsys.com/product/wattnode-bacnet/
on our website.
●
Option CT=xxx
- Pre-assign xxx as the
CtAmpsA, B, and C
values.
●
Option CT=xxx/yyy/zzz
- Pre-assign xxx to
CtAmpsA
, yyy to
CtAmpsB
, and zzz to
CtAmpsC
.
●
Option TM1
- Configure the meter for use with a 10k thermistor between the
C
and
X
termi-
nals. This will use firmware version 1.20, which is not BTL certified. See also
and
