24 Installation
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In some cases, this can also occur if the CT wires are connected to the wrong inputs, such
as if the CT wires for phases B and C are swapped.
Note: if all three LEDs are flashing red and they always turn on and off together, like the diagram
for
below, then the meter is experiencing an error or low line voltage, not nega-
tive power.
Low Power Factor
The meter will display yellow flashing or red/yellow flashing on
any phase with low power factor. This may be normal for your
load, or it may indicate that the CTs are not installed correctly.
Yellow flashing or yellow/red flashing indicates that the current lags the voltage by 60 degrees or
more (power factor less than 0.5), or that the current leads the voltage by 30 degrees or more.
Yellow/red also indicates negative power (energy flowing from the load to the grid). Yellow flash-
ing (positive power) can happen for a variety of reasons, some of which occur during correct
operation.
●
Small appliances sometimes have low power factors.
●
At light loads, motors, power supplies, and some other devices have low power factors.
●
Traditional florescent light ballasts can have power factors as low as 0.4.
●
Three-phase delta configurations can result in low power factors, especially if one of the
phases is grounded.
●
The CTs are not installed on the correct line phases. For example, if you connect phases A, B
and C to the respective Vac inputs on the meter, but then the CTs for A, B, and C are con-
nected in the wrong order to the meter, say B, A, C, then the power measured on phases A
and B will have an extra 120 degree phase shift between voltage and current, resulting in a
low power factor and probably negative power.
Yellow/red flashing (negative power) is less common and indicates incorrect installation unless
you are generating power, as with PV (solar) power generation. When monitoring house—or
building—power with PV (solar) power generation, the combination of the house load and the PV
generated power can result in a net power with a low power factor.
In general, if you see yellow or yellow/red flashing for one or more phases check the following:
●
Check that your load is turned on (since standby power supplies can have low power factors).
●
Check that the CT phases match the phases for the Vac connections.
●
Check that none of the CTs are installed backwards on the current carrying conductor and
that the white and black CT leads are connected to the correct CT input terminals (the black
wire should match up to the black circle on the label and the white wire to the white circle).
●
Consider whether your load may have an unusual power factor. Loads like heaters, incandes-
cent lights, and power factor corrected loads should have a power factor near 1.0 and should
not cause the LEDs to flash yellow. Loads like motors, florescent light ballasts, etc. may have
low power factors, in which case, yellow flashing may be normal.
Erratic Flashing
If the LEDs are flashing slowly and erratically, sometimes
green, sometimes red or yellow, this generally indicates
one of the following:
●
Earth ground is not connected to the meter (the top
connection on the green screw terminal).
●
Voltage is connected for a phase, but the current transformer is not connected, or the CT has
a loose connection.
Yellow
Off
Yellow
Off
Yellow
Off
Yellow
Red
Yellow
Red
Yellow
Red
Grn
Red
Grn
Yellow
Red
Grn
Red
C
B
A
Off
Off
Off
Off
Off
Red
Off
Red
Off
