Manual

Measurement Channels and Alarms
IM 04L21B01-01EN
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App
Index
3.12 Measuring Power (/PWR1 Option)
Power Monitor Function
Measure the measurement elements of electrical power. Set an expression on a
computation channel, and then start the computation to begin the measurement.
In addition, by using other operators, you can measure the maximum, minimum, average
and electric energy.
Measurement Element Symbol Description
Active or regenerative power WAT Power values without the low-cut
function applied.
Active power WATP
Regenerative power WATN
Reactive power VAR
Reactive power (LAG) VARP
Reactive power (LEAD) VARN
Apparent power VA
Active or regenerative power (low-cut) _WAT_ Power values with the low-cut
function applied. The electric energy
is measured by summing these
measurement elements.
The low-cut function sets the
measured value to 0 when the
measured value is less than the set
low-cut power. With no load, this
function prevents the influence of noise
present in each measurement element
from accumulating in the power
consumption (Wh) calculation.
Active power (low-cut) _WATP_
Regenerative power (low-cut) _WATN_
Reactive power (low-cut) _VAR_
Reactive power (LAG; low-cut) _VARP_
Reactive power (LEAD; low-cut) _VARN_
Apparent power (low-cut) _VA_
Voltage (V1) VOL1 This is the voltage.
Voltage (V2) VOL2 This is the voltage. This is only valid
for single-phase three-wire systems.
Voltage (V3) VOL3 This is the voltage. This is only valid
for three-phase three-wire systems.
Current (I1) CUR1 This is the current.
Current (I2) CUR2 This is the current. This is only valid for
single-phase three-wire systems.
Current (I3) CUR3 This is the current. This is only valid for
three-phase three-wire systems.
Frequency HZ This is the frequency.
Power factor PF This is the power factor.
Measuring Electric Energy
The electric energy is calculated by summing the measured values of the power
measurement channels. To avoid the influence of noise in this calculation, normally use
the low-cut function. On the FX, sum powers to which the low-cut function has been
applied (_WAT_, _WATP_, _WATN_, _VAR_, _VARP_, _VARN_, and _VA_ in the above
table) to measure the electric energy. You can set the low-cut point to any value that you
want.
• Computation Channels
You can write expressions in computation channels to measure the electric energy.
You have to set an expression—one which will be used to sum the measured power
values—in a computation channel. The sum is set using the TLOG expression and
the timer (see example 4 in this section). The TLOG expressions are shown in the
following table.