YOKOGAWA WT500 - Guide for Selecting the Method Used to Measure the Power

3-13
IM 760201-01E
Before You Start Measuring
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App
Index
3.8 Guide for Selecting the Method Used to
Measure the Power
Select the measurement method according to the amplitude of the measured voltage
or current from the table below. For details about a wiring system or method, see its
corresponding section indicated in the table.
Voltage Measurement Methods
When the voltage is less
than or equal to 1000 V
When the voltage
exceeds 1000 V
See section 3.9
Voltage
wiring
Direct input is not possible
See section 3.11
Direct input
VT (voltage transformer)
Current Measurement Methods
When the voltage is less
than or equal to 1000 V
When the current is
less than or equal
to 40 A
When the current
exceeds 40 A
When the voltage
exceeds 1000 V
See section 3.9
Current
wiring
Direct input is not possible
Shunt resistors
cannot be used
See section 3.10
See section 3.10
See section 3.11
See section 3.11
Direct input
Shunt resistor
Clamp-type current sensor
(voltage output type)
Clamp-type current sensor
(current output type)
CT (current transformer)
Notes when Replacing Other Power Meters with the WT500
In three-phase, three-wire systems (3P3W) and three-phase, three-wire systems that use
a three-voltage, three-current method (3P3W; 3V3A), the wiring system of the WT500
may be different from that of another product (another digital power meter) depending
on whether the reference voltage used to measure the line voltage (see appendix 4 for
details) is based on single-phase or three-phase power. To make correct measurements,
see the referenced sections in the selection guide above and check the wiring method of
the three-phase, three-wire system.
The three-phase, three-wire
systems are different
WT500
WT3000
WT1600
PZ4000
WT2000
WT1000
WT230
WT130
2533
2532
etc.
For example, if you replace the WT2000 (used in a three-phase, three-wire system) with
the WT500 and leave the wiring unchanged, the measured power of each element will
be different between the WT2000 and the WT500. Refer to this manual and re-wire the
system correctly.
Note
In the wiring examples that follow, models are referred to by number. For information about the
different WT500 models and their specifications, see page iii.