YOKOGAWA WT1800 User Manual

4-9
IM WT1801-01EN
Motor Efficiency and Total Efficiency Computation
The WT1800 can compute the motor efficiency (the ratio of power consumption to motor output) and total
efficiency from the active power and motor output that it measures.
*
You can set the efficiency equation using the
η Formula setting.
Click here.
* The total efficiency is the ratio of total power consumption—not just the power consumption of the motor but
also the power consumption of the converter that supplies the motor with power—to motor output.
The following is an example of how the values are computed.
When the Motor Input Is Wired to ΣA
×100
Motor output Pm (W)
PΣA(W)
Motor efficiency (%) =
Motor Motor output Pm
Motor power
consumption
P
ΣA
When the Converter and Motor Inputs Are Wired to ΣA and ΣB, Respectively
×100
Motor output Pm (W)
PΣB(W)
Motor efficiency (%) =
×100
Motor output Pm (W)
PΣA(W)
Total efficiency (%) =
Converter
(inverter, etc.)
Motor Motor output Pm
PΣBPΣA
Motor power
consumption
Motor and converter
power consumption
When the Converter and Motor Inputs Are Wired to ΣB and ΣA, Respectively
×100
Motor output Pm (W)
PΣA(W)
Motor efficiency (%) =
×100
Motor output Pm (W)
PΣB(W)
Total efficiency (%) =
Converter
(inverter, etc.)
Motor Motor output Pm
PΣA
Motor power
consumption
PΣB
Motor and converter
power consumption
If ΣA or ΣB is a three-phase, three-wire (3P3W) system, you can use delta computation to perform
3P3W>3V3A transformation on ΣA and ΣB. From the 3P3W>3V3A transformation, you can determine one
unmeasured line voltage and one unmeasured common mode current.
4 Motor Evaluation Conditions (Option)

YOKOGAWA WT1800 Specifications

General

Model	WT1800
Basic Power Accuracy	±0.1% of reading
Frequency Range	DC, 0.1 Hz to 1 MHz
Harmonic Analysis	Yes, up to 500th order
Voltage Range	1.5 V to 1000 V
Current Range	0.5 A to 50 A
Display	8.4-inch LCD
Interfaces	USB, Ethernet, GP-IB
Sampling Rate	2 MS/s
Dimensions	426 mm x 177 mm x 400 mm