Wiring Precautions - YOKOGAWA WT200 User Manual

3.3

Wiring Precautions

3-4
• 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 16 "Specifications."
Max allowable input
Instantaneous max
(for 1s)
Continuous
• 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 + 1000 V 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 rating across the input (voltage and current) and ground varies depending
on the 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 600 Vrms 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 400 Vrms max.
Voltage across V terminal and ground 600 Vrms max.
WARNING
Voltage input
Peak value of 2000 V or
RMS value of 1500 V,
whichever is less.
Peak value of 1500 V or
RMS valueof 1000 V,
whichever is less.
Current input
20 A to 0.5 A range
Peak value of 150 A or RMS value of
40 A, whichever is less.
200 mA to 5 mA range
Peak value of 30 A or RMS value of
20 A, whichever is less.
20 A to 0.5 A range
Peak value of 100 A or RMS value of
25 A, whichever is less.
200 mA to 5 mA range
Peak value of 30 A or RMS value of
20 A, whichever is less.
IM 253421-01E