YOKOGAWA WT500 User Manual page 70

IM 760201-01E
3.5 Precautions for Wiring the Circuit That You Will Measure
• To make the protective measures effective, before applying the voltage or
current from the circuit under measurement, check that:
• The power cord provided with the instrument is being used to connect to the
power supply and that the instrument is grounded.
• The instrument's power switch is turned on.
• The current input protective cover provided with the instrument is being used.
• When the instrument's power switch is turned on, do not apply a signal that
exceeds the following values to the voltage or current input terminals. When the
instrument is turned off, turn off the circuit under measurement. For information
about other input terminals, see chapter 14.
Instantaneous Maximum Allowable Input (1 s or less)
Voltage Input
Peak value of 2000 V or rms value of 1500 V, whichever is less.
Current input
Direct input
Peak value of 150 A or rms value of 45 A, whichever is less.
External Sensor Input
Peak value less than or equal to 10 times the range.
Continuous Maximum Allowable Input
Voltage Input
Peak value of 1500 V or rms value of 1000 V, whichever is less.
Current input
Direct input
Peak value of 100 A or rms value of 45 A, whichever is less.
External Sensor Input
Peak value less than or equal to 5 times the range.
• Use measurement cables with dielectric strengths and current capacities that
are appropriate for the voltage or current being measured.
Example: When making measurements on a current of 20 A, use copper wires
that have a conductive cross-sectional area of 4 mm
• Connecting cables may cause radio interference, in which case users will be
required to correct the interference.
Note
• After you finish wiring, you must select the wiring system. For details, see section 4.2,
"Selecting the Wiring System."
• If you are measuring large currents, voltages or currents that contain high frequency
components, take special care in dealing with mutual interference and noise when wiring.
• Keep measurement cables as short as possible to minimize the loss between the circuit
under measurement and the instrument.
• The thick lines on the wiring diagrams shown in sections 3.9 to 3.11 are the sections where
the current flows. Use wires that are suitable for the current levels.
• To make accurate measurements of the voltage of the circuit under measurement, connect
the cable to the circuit as closely as possible.
• To make correct measurements, separate the measurement cables as far away from the
ground wires and the instrument's case as possible to minimize static capacitance to the
ground.
• To measure the apparent power and power factor more accurately on an unbalanced three-
phase circuit, we recommend that you use a three-voltage, three-current method with a
three-phase, three-wire system (3P3W; 3V3A).
CAUTION
1
2
3
4
5
6
7
8
9
2
. or greater. 10
11
12
13
14
App
Index
3-9