3-6
IM 253710-01E
3.4
Wiring Precautions
To prevent electric shock and damage to the instrument, follow the precautions below.
WARNING
• To ensure safety, if the current to be measured exceeds 7 A (RMS), use a cable
or conductor that allows current greater than the current to be measured to flow
through it, and always connect protective grounding prior to use of this
instrument. For products shipped as of January 2004, the protective earth
terminal is located* on the rear panel.
*
If you need to confirm whether a protective earth terminal is installed, please contact the
dealer from whom you purchased the instrument.
• Employ protective earth ground before connecting measurement cables.
• When wiring the circuit under measurement, turn OFF its power. Wiring or
removing the cables without turning OFF the power is dangerous.
• Take special caution not to wire a current circuit to the voltage input terminal or
a voltage circuit to the current input terminal.
• Strip the insulation cover of the measurement cable so that when it is wired to
the input terminal, the conductive parts (bare wires) do not protrude from the
terminal. Also, make sure to fasten the input terminal screws securely so that
the cable does not come loose.
• Use cables with safety terminals that cover the conductive parts for connecting
to the voltage input terminals. Using a terminal with bare conductive parts (such
as a banana plug) is dangerous when the terminal comes loose.
• Use cables with safety terminals that cover the conductive parts for connecting
to the current sensor input terminals. Using a terminal with bare conductive
parts is dangerous when the terminal comes loose.
• Some input modules have multiple systems of current input terminals. Note that
only one system (one set of current input terminals) can be used on a module at
any given time. Remove all other cables connected to the current input
terminals or current sensor input connector.
• When the voltage of the circuit under measurement is being applied to the
current input terminals, do not touch the other current input terminals or current
sensor terminals. Since these terminals are electrically connected inside the
instrument, this act is dangerous.
• When connecting measurement cables from an external current sensor to the
current sensor input connector, remove the cables connected to the current
input terminals. In addition, when the voltage of the circuit under measurement
is being applied to the current sensor input terminal, do not touch the other
current input terminals or current sensor terminals. Since these terminals are
electrically connected inside the instrument, this act is dangerous.
• When using the external potential transformer (PT) or current transformer (CT),
make sure it has enough withstand voltage with respect to the voltage (U) being
measured (2U + 1000 V recommended). Also, make sure that the secondary
side of the CT does not become an open circuit while the power is being
applied. Otherwise, high voltage will appear at the secondary side of the CT,
making it extremely dangerous.
• When using an external current sensor, make sure to use a sensor that comes
in a case. The conductive parts and the case should be insulated, and the
sensor should have enough withstand voltage with respect to the voltage being
measured. Using a bare sensor is dangerous, because you might accidentally
come in contact with it.
• When using a shunt-type current sensor as an external current sensor, turn OFF
the circuit under measurement. If power is being applied, the voltage of the
circuit under measurement will be applied to the shunt-type current sensor,
making it dangerous.
