11
VC21
INSTALLATION GUIDE
Real Time Energy Metering
VC21 User Manual
UPDATED: 10.9.12
LED State Condition:
The Red DIAG (diagnostic) LED has a variety of functions. Depending on the state of
the LED, it can signify a number of conditions. The table below summarizes the LED
states and related conditions:
LED State
Condition
OFF
Normal operation, or insufficient power
supply voltage (see step 1)
Fast Flashing
Input Voltages below threshold
(typically ≤ 25 VAC)
Solid (ON)
Reverse NET Power (kW) condition
Slow Flashing
Reverse Sequence (typically this is
disabled from the factory)
Double-Flash, pause,
Double-Flash
Firmware update mode check: DIP
Address switch must not be “0”.
Potential firmware problem.
To test for WattsOn functionality, it is best to connect power and disconnect voltage
inputs. In this configuration, the RED LED should flash rapidly. This is an indication of
proper operation.
During normal measurement operation (i.e. voltage inputs above 25VAC), the DIAG
LED should be OFF. If the LED stays ON constantly, or turns on an off erratically, it
is an indication of reverse power detection. This condition arises when the SUM of
the real power (watts) in all three phases is negative. Please note however, in a three-
phase system (assuming balanced phases), if only one of the phases is reversed, the
NET will continue to be positive.
