3-19
IM 253710-01E
Before Starting Measurements
3
3.9
Using an External PT or CT to Wire the Circuit
under Measurement
Connect a measurement cable from an external potential transformer (PT) or current
transformer (CT) to the voltage or current input terminal of the power measurement
module.
To prevent electric shock and damage to the instrument follow the precautions given in
section 3.4, “Wiring Precautions.”
• An external PT can be used to make measurements when the maximum voltage
value of the circuit under measurement exceeds the maximum measurement range of
the power measurement module, “1000 Vrms” or “2000 Vpeak.”
• An external CT can be used to make measurements when the maximum current value
of the circuit under measurement exceeds the maximum current range of the power
measurement module.
• Power measurement module 253751
When the maximum current exceeds “7 Arms” or “10 Apeak.”
• Power measurement module 253752
• 5-A terminal : When the maximum current exceeds “7 Arms” or “10 Apeak.”
• 20-A terminal : When the maximum current exceeds “30 Arms” or “100 Apeak.”
Connecting to the Input Terminal
Voltage input terminal
Insert the safety terminal (the conductive parts are not exposed) into the voltage input
terminal
Current input terminal
The power measurement module 253751 has 5-A terminals.
Power measurement module 253752 has two types of terminals, 5-A and 20-A
terminals, but only one system of current input (one set of current input terminals) can
be used on each input module at one time. To prevent electric shock and damage to
the instrument, do not wire measurement cables to multiple current input terminals
simultaneously.
The screws used on the terminal (binding post) are M6 screws. Either wind the wire
around the screw or pass the crimp-on lugs through the screw axis, then tighten firmly
by holding the terminal knob.
For precautions during and after connection of the current input terminal and crimp-on
lugs, see section 3.7.
Combination of Wiring Methods and Elements
The combination of the selectable wiring methods and elements varies depending on the
number of installed power measurement modules. For details, see “Combination of
Wiring Methods and Elements” and “Wiring Examples” in section 3.7, “Directly Wiring the
Circuit under Measurement.”
