IM 253401-01E
3-4
3.3
Wiring Precautions
WARNING
• To prevent hazards, make sure to apply a ground protection before
connecting the object being measured.
• Always turn OFF the power to the object being measured before
connecting it to the instrument. Never connect or disconnect the
measurement lead wires from the object while power is being supplied to it,
otherwise a serious accident may result.
• When the power switch is ON, never apply a voltage or current exceeding
the level specified in the table below to the voltage input or current input
terminal. When the power switch is OFF, turn off the power of the
instrument under measurement as well.
For details regarding the other terminals, such as the external input
terminal, refer to chapter 15 “Specifications”.
Max allowable input
Voltage input
Current input
Instantaneous max
(for 1s)
The peak value is 2000V
or the RMS value is 1500V,
whichever is less
The peak value is 150A
or the RMS value is 40A,
whichever is less
Continuous
The peak value is 1500V
or the RMS value is 1000V,
whichever is less
The peak value is 100A
or the RMS value is 30A,
whichever is less
• In case you are using an external potential transformer (PT) or current
transformer (CT), use one which has a sufficient withstand voltage against
the voltage to be measured (a withstand voltage of 2E + 1000V is
recommended, where E is the measurement voltage.) Also be sure not to
allow the secondary side of the CT to go open-circuit while power is
supplied, otherwise an extremely dangerous high voltage will be generated
on the secondary side of the CT.
• If the instrument is used in a rack, provide a power switch so that power to
the instrument can be shut off from the front of the rack in an emergency.
• For safety reasons, make sure that the bare end of the measurement lead
wire connected to each input terminal does not protrude from the terminal.
Also make sure that the measurement lead wires are connected to the
terminals securely.
• The voltage ratings across the measuring (voltage and current) input and
the ground for this instrument varies under operating conditions.
• When protective covers are used on GP-IB or RS-232-C and external
input/output connectors;
Voltage across each measuring input terminal and ground 600Vrms max.
• When protective covers are removed from GP-IB or RS-232-C and from
external input/output connectors; or when connectors are used;
Voltage across A,
±
(V and A side) input terminals and ground 400Vrms max.
Voltage across V terminal and ground 600Vrms max.
CAUTION
• The lead wires must have a sufficient margin in both withstand voltage and
current against those to be measured. They must also have insulation
resistance appropriate to their ratings. Ex. If measurement is carried out on
a current of 20A, use copper wires with a conductor cross-sectional area of
at least 4mm
2
.
Note
• After completing the wiring of the WT130, the WIRING key needs to be used to select the wiring
system before starting measurements. Refer to section 3.9, page 3-15.
• When measuring high currents, or currents or voltages that contain high-frequency components, wiring
should be made with special attention paid to possible mutual interference and noise problems.
• Keep the lead wires short as possible.
• For current circuits indicated by thick lines in the wiring diagrams shown in section 3.3, use thick lead
wires appropriate for the current to be measured.
• The lead wire to the voltage input terminal should be connected as close to the load of the object under
measurement as possible.
• To minimize stray capacitance to ground, route both lead wires and grounding wires so that they are as
away from the instrument's case as possible.
